/*
- * Copyright (c) 2010-2018 ARM Limited
+ * Copyright (c) 2010-2019 ARM Limited
* All rights reserved.
*
* The license below extends only to copyright in the software and shall
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- * Authors: Erik Hallnor
- * Dave Greene
- * Nathan Binkert
- * Steve Reinhardt
- * Ron Dreslinski
- * Andreas Sandberg
- * Nikos Nikoleris
*/
/**
#include "mem/cache/cache.hh"
+#include <cassert>
+
+#include "base/compiler.hh"
#include "base/logging.hh"
+#include "base/trace.hh"
#include "base/types.hh"
#include "debug/Cache.hh"
-#include "debug/CachePort.hh"
#include "debug/CacheTags.hh"
#include "debug/CacheVerbose.hh"
-#include "mem/cache/blk.hh"
+#include "enums/Clusivity.hh"
+#include "mem/cache/cache_blk.hh"
#include "mem/cache/mshr.hh"
-#include "mem/cache/prefetch/base.hh"
-#include "sim/sim_exit.hh"
-
-Cache::Cache(const CacheParams *p)
- : BaseCache(p, p->system->cacheLineSize()),
- tags(p->tags),
- prefetcher(p->prefetcher),
- doFastWrites(true),
- prefetchOnAccess(p->prefetch_on_access),
- clusivity(p->clusivity),
- writebackClean(p->writeback_clean),
- tempBlockWriteback(nullptr),
- writebackTempBlockAtomicEvent([this]{ writebackTempBlockAtomic(); },
- name(), false,
- EventBase::Delayed_Writeback_Pri)
-{
- tempBlock = new CacheBlk();
- tempBlock->data = new uint8_t[blkSize];
-
- cpuSidePort = new CpuSidePort(p->name + ".cpu_side", this,
- "CpuSidePort");
- memSidePort = new MemSidePort(p->name + ".mem_side", this,
- "MemSidePort");
-
- tags->setCache(this);
- if (prefetcher)
- prefetcher->setCache(this);
-}
-
-Cache::~Cache()
-{
- delete [] tempBlock->data;
- delete tempBlock;
-
- delete cpuSidePort;
- delete memSidePort;
-}
-
-void
-Cache::regStats()
-{
- BaseCache::regStats();
-}
-
-void
-Cache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
+#include "mem/cache/tags/base.hh"
+#include "mem/cache/write_queue_entry.hh"
+#include "mem/request.hh"
+#include "params/Cache.hh"
+
+Cache::Cache(const CacheParams &p)
+ : BaseCache(p, p.system->cacheLineSize()),
+ doFastWrites(true)
{
- assert(pkt->isRequest());
-
- uint64_t overwrite_val;
- bool overwrite_mem;
- uint64_t condition_val64;
- uint32_t condition_val32;
-
- int offset = tags->extractBlkOffset(pkt->getAddr());
- uint8_t *blk_data = blk->data + offset;
-
- assert(sizeof(uint64_t) >= pkt->getSize());
-
- overwrite_mem = true;
- // keep a copy of our possible write value, and copy what is at the
- // memory address into the packet
- pkt->writeData((uint8_t *)&overwrite_val);
- pkt->setData(blk_data);
-
- if (pkt->req->isCondSwap()) {
- if (pkt->getSize() == sizeof(uint64_t)) {
- condition_val64 = pkt->req->getExtraData();
- overwrite_mem = !std::memcmp(&condition_val64, blk_data,
- sizeof(uint64_t));
- } else if (pkt->getSize() == sizeof(uint32_t)) {
- condition_val32 = (uint32_t)pkt->req->getExtraData();
- overwrite_mem = !std::memcmp(&condition_val32, blk_data,
- sizeof(uint32_t));
- } else
- panic("Invalid size for conditional read/write\n");
- }
-
- if (overwrite_mem) {
- std::memcpy(blk_data, &overwrite_val, pkt->getSize());
- blk->status |= BlkDirty;
- }
+ assert(p.tags);
+ assert(p.replacement_policy);
}
-
void
Cache::satisfyRequest(PacketPtr pkt, CacheBlk *blk,
bool deferred_response, bool pending_downgrade)
{
- assert(pkt->isRequest());
-
- assert(blk && blk->isValid());
- // Occasionally this is not true... if we are a lower-level cache
- // satisfying a string of Read and ReadEx requests from
- // upper-level caches, a Read will mark the block as shared but we
- // can satisfy a following ReadEx anyway since we can rely on the
- // Read requester(s) to have buffered the ReadEx snoop and to
- // invalidate their blocks after receiving them.
- // assert(!pkt->needsWritable() || blk->isWritable());
- assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
-
- // Check RMW operations first since both isRead() and
- // isWrite() will be true for them
- if (pkt->cmd == MemCmd::SwapReq) {
- cmpAndSwap(blk, pkt);
- } else if (pkt->isWrite()) {
- // we have the block in a writable state and can go ahead,
- // note that the line may be also be considered writable in
- // downstream caches along the path to memory, but always
- // Exclusive, and never Modified
- assert(blk->isWritable());
- // Write or WriteLine at the first cache with block in writable state
- if (blk->checkWrite(pkt)) {
- pkt->writeDataToBlock(blk->data, blkSize);
- }
- // Always mark the line as dirty (and thus transition to the
- // Modified state) even if we are a failed StoreCond so we
- // supply data to any snoops that have appended themselves to
- // this cache before knowing the store will fail.
- blk->status |= BlkDirty;
- DPRINTF(CacheVerbose, "%s for %s (write)\n", __func__, pkt->print());
- } else if (pkt->isRead()) {
- if (pkt->isLLSC()) {
- blk->trackLoadLocked(pkt);
- }
-
- // all read responses have a data payload
- assert(pkt->hasRespData());
- pkt->setDataFromBlock(blk->data, blkSize);
+ BaseCache::satisfyRequest(pkt, blk);
+ if (pkt->isRead()) {
// determine if this read is from a (coherent) cache or not
if (pkt->fromCache()) {
assert(pkt->getSize() == blkSize);
// if we have a dirty copy, make sure the recipient
// keeps it marked dirty (in the modified state)
- if (blk->isDirty()) {
+ if (blk->isSet(CacheBlk::DirtyBit)) {
pkt->setCacheResponding();
- blk->status &= ~BlkDirty;
+ blk->clearCoherenceBits(CacheBlk::DirtyBit);
}
- } else if (blk->isWritable() && !pending_downgrade &&
- !pkt->hasSharers() &&
- pkt->cmd != MemCmd::ReadCleanReq) {
- // we can give the requester a writable copy on a read
+ } else if (blk->isSet(CacheBlk::WritableBit) &&
+ !pending_downgrade && !pkt->hasSharers() &&
+ pkt->cmd != MemCmd::ReadCleanReq) {
+ // we can give the requestor a writable copy on a read
// request if:
// - we have a writable copy at this level (& below)
// - we don't have a pending snoop from below
// snooping the packet)
// - the read has explicitly asked for a clean
// copy of the line
- if (blk->isDirty()) {
+ if (blk->isSet(CacheBlk::DirtyBit)) {
// special considerations if we're owner:
if (!deferred_response) {
// respond with the line in Modified state
// the cache hierarchy through a cache,
// and first snoop upwards in all other
// branches
- blk->status &= ~BlkDirty;
+ blk->clearCoherenceBits(CacheBlk::DirtyBit);
} else {
// if we're responding after our own miss,
// there's a window where the recipient didn't
pkt->setHasSharers();
}
}
- } else if (pkt->isUpgrade()) {
- // sanity check
- assert(!pkt->hasSharers());
-
- if (blk->isDirty()) {
- // we were in the Owned state, and a cache above us that
- // has the line in Shared state needs to be made aware
- // that the data it already has is in fact dirty
- pkt->setCacheResponding();
- blk->status &= ~BlkDirty;
- }
- } else {
- assert(pkt->isInvalidate());
- invalidateBlock(blk);
- DPRINTF(CacheVerbose, "%s for %s (invalidation)\n", __func__,
- pkt->print());
}
}
Cache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
PacketList &writebacks)
{
- // sanity check
- assert(pkt->isRequest());
- chatty_assert(!(isReadOnly && pkt->isWrite()),
- "Should never see a write in a read-only cache %s\n",
- name());
+ if (pkt->req->isUncacheable()) {
+ assert(pkt->isRequest());
- DPRINTF(CacheVerbose, "%s for %s\n", __func__, pkt->print());
+ chatty_assert(!(isReadOnly && pkt->isWrite()),
+ "Should never see a write in a read-only cache %s\n",
+ name());
- if (pkt->req->isUncacheable()) {
- DPRINTF(Cache, "uncacheable: %s\n", pkt->print());
+ DPRINTF(Cache, "%s for %s\n", __func__, pkt->print());
// flush and invalidate any existing block
CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure()));
if (old_blk && old_blk->isValid()) {
- if (old_blk->isDirty() || writebackClean)
- writebacks.push_back(writebackBlk(old_blk));
- else
- writebacks.push_back(cleanEvictBlk(old_blk));
- invalidateBlock(old_blk);
+ BaseCache::evictBlock(old_blk, writebacks);
}
blk = nullptr;
return false;
}
- // Here lat is the value passed as parameter to accessBlock() function
- // that can modify its value.
- blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat);
-
- DPRINTF(Cache, "%s %s\n", pkt->print(),
- blk ? "hit " + blk->print() : "miss");
-
- if (pkt->req->isCacheMaintenance()) {
- // A cache maintenance operation is always forwarded to the
- // memory below even if the block is found in dirty state.
-
- // We defer any changes to the state of the block until we
- // create and mark as in service the mshr for the downstream
- // packet.
- return false;
- }
-
- if (pkt->isEviction()) {
- // We check for presence of block in above caches before issuing
- // Writeback or CleanEvict to write buffer. Therefore the only
- // possible cases can be of a CleanEvict packet coming from above
- // encountering a Writeback generated in this cache peer cache and
- // waiting in the write buffer. Cases of upper level peer caches
- // generating CleanEvict and Writeback or simply CleanEvict and
- // CleanEvict almost simultaneously will be caught by snoops sent out
- // by crossbar.
- WriteQueueEntry *wb_entry = writeBuffer.findMatch(pkt->getAddr(),
- pkt->isSecure());
- if (wb_entry) {
- assert(wb_entry->getNumTargets() == 1);
- PacketPtr wbPkt = wb_entry->getTarget()->pkt;
- assert(wbPkt->isWriteback());
-
- if (pkt->isCleanEviction()) {
- // The CleanEvict and WritebackClean snoops into other
- // peer caches of the same level while traversing the
- // crossbar. If a copy of the block is found, the
- // packet is deleted in the crossbar. Hence, none of
- // the other upper level caches connected to this
- // cache have the block, so we can clear the
- // BLOCK_CACHED flag in the Writeback if set and
- // discard the CleanEvict by returning true.
- wbPkt->clearBlockCached();
- return true;
- } else {
- assert(pkt->cmd == MemCmd::WritebackDirty);
- // Dirty writeback from above trumps our clean
- // writeback... discard here
- // Note: markInService will remove entry from writeback buffer.
- markInService(wb_entry);
- delete wbPkt;
- }
- }
- }
-
- // Writeback handling is special case. We can write the block into
- // the cache without having a writeable copy (or any copy at all).
- if (pkt->isWriteback()) {
- assert(blkSize == pkt->getSize());
-
- // we could get a clean writeback while we are having
- // outstanding accesses to a block, do the simple thing for
- // now and drop the clean writeback so that we do not upset
- // any ordering/decisions about ownership already taken
- if (pkt->cmd == MemCmd::WritebackClean &&
- mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
- DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
- "dropping\n", pkt->getAddr());
- return true;
- }
-
- if (blk == nullptr) {
- // need to do a replacement
- blk = allocateBlock(pkt->getAddr(), pkt->isSecure(), writebacks);
- if (blk == nullptr) {
- // no replaceable block available: give up, fwd to next level.
- incMissCount(pkt);
- return false;
- }
- tags->insertBlock(pkt, blk);
-
- blk->status |= (BlkValid | BlkReadable);
- }
- // only mark the block dirty if we got a writeback command,
- // and leave it as is for a clean writeback
- if (pkt->cmd == MemCmd::WritebackDirty) {
- assert(!blk->isDirty());
- blk->status |= BlkDirty;
- }
- // if the packet does not have sharers, it is passing
- // writable, and we got the writeback in Modified or Exclusive
- // state, if not we are in the Owned or Shared state
- if (!pkt->hasSharers()) {
- blk->status |= BlkWritable;
- }
- // nothing else to do; writeback doesn't expect response
- assert(!pkt->needsResponse());
- pkt->writeDataToBlock(blk->data, blkSize);
- DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
- incHitCount(pkt);
- // populate the time when the block will be ready to access.
- blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
- pkt->payloadDelay;
- return true;
- } else if (pkt->cmd == MemCmd::CleanEvict) {
- if (blk != nullptr) {
- // Found the block in the tags, need to stop CleanEvict from
- // propagating further down the hierarchy. Returning true will
- // treat the CleanEvict like a satisfied write request and delete
- // it.
- return true;
- }
- // We didn't find the block here, propagate the CleanEvict further
- // down the memory hierarchy. Returning false will treat the CleanEvict
- // like a Writeback which could not find a replaceable block so has to
- // go to next level.
- return false;
- } else if (pkt->cmd == MemCmd::WriteClean) {
- // WriteClean handling is a special case. We can allocate a
- // block directly if it doesn't exist and we can update the
- // block immediately. The WriteClean transfers the ownership
- // of the block as well.
- assert(blkSize == pkt->getSize());
-
- if (!blk) {
- if (pkt->writeThrough()) {
- // if this is a write through packet, we don't try to
- // allocate if the block is not present
- return false;
- } else {
- // a writeback that misses needs to allocate a new block
- blk = allocateBlock(pkt->getAddr(), pkt->isSecure(),
- writebacks);
- if (!blk) {
- // no replaceable block available: give up, fwd to
- // next level.
- incMissCount(pkt);
- return false;
- }
- tags->insertBlock(pkt, blk);
-
- blk->status |= (BlkValid | BlkReadable);
- }
- }
-
- // at this point either this is a writeback or a write-through
- // write clean operation and the block is already in this
- // cache, we need to update the data and the block flags
- assert(blk);
- assert(!blk->isDirty());
- if (!pkt->writeThrough()) {
- blk->status |= BlkDirty;
- }
- // nothing else to do; writeback doesn't expect response
- assert(!pkt->needsResponse());
- pkt->writeDataToBlock(blk->data, blkSize);
- DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
-
- incHitCount(pkt);
- // populate the time when the block will be ready to access.
- blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
- pkt->payloadDelay;
- // if this a write-through packet it will be sent to cache
- // below
- return !pkt->writeThrough();
- } else if (blk && (pkt->needsWritable() ? blk->isWritable() :
- blk->isReadable())) {
- // OK to satisfy access
- incHitCount(pkt);
- satisfyRequest(pkt, blk);
- maintainClusivity(pkt->fromCache(), blk);
-
- return true;
- }
-
- // Can't satisfy access normally... either no block (blk == nullptr)
- // or have block but need writable
-
- incMissCount(pkt);
-
- if (blk == nullptr && pkt->isLLSC() && pkt->isWrite()) {
- // complete miss on store conditional... just give up now
- pkt->req->setExtraData(0);
- return true;
- }
-
- return false;
-}
-
-void
-Cache::maintainClusivity(bool from_cache, CacheBlk *blk)
-{
- if (from_cache && blk && blk->isValid() && !blk->isDirty() &&
- clusivity == Enums::mostly_excl) {
- // if we have responded to a cache, and our block is still
- // valid, but not dirty, and this cache is mostly exclusive
- // with respect to the cache above, drop the block
- invalidateBlock(blk);
- }
+ return BaseCache::access(pkt, blk, lat, writebacks);
}
void
// below. We can discard CleanEvicts because cached
// copies exist above. Atomic mode isCachedAbove
// modifies packet to set BLOCK_CACHED flag
- memSidePort->sendAtomic(wbPkt);
+ memSidePort.sendAtomic(wbPkt);
}
} else {
// If the block is not cached above, send packet below. Both
// CleanEvict and Writeback with BLOCK_CACHED flag cleared will
// reset the bit corresponding to this address in the snoop filter
// below.
- memSidePort->sendAtomic(wbPkt);
+ memSidePort.sendAtomic(wbPkt);
}
writebacks.pop_front();
// In case of CleanEvicts, the packet destructor will delete the
{
DPRINTF(Cache, "%s for %s\n", __func__, pkt->print());
- assert(pkt->isResponse());
- assert(!system->bypassCaches());
-
// determine if the response is from a snoop request we created
// (in which case it should be in the outstandingSnoop), or if we
// merely forwarded someone else's snoop request
Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay;
// Reset the timing of the packet.
pkt->headerDelay = pkt->payloadDelay = 0;
- memSidePort->schedTimingSnoopResp(pkt, snoop_resp_time);
+ memSidePort.schedTimingSnoopResp(pkt, snoop_resp_time);
}
void
{
// Cache line clearing instructions
if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) &&
- (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) {
+ (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0) &&
+ !pkt->isMaskedWrite()) {
pkt->cmd = MemCmd::WriteLineReq;
DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n");
}
// lookup
assert(!pkt->req->isUncacheable());
- if (pkt->needsResponse()) {
- pkt->makeTimingResponse();
- // @todo: Make someone pay for this
- pkt->headerDelay = pkt->payloadDelay = 0;
-
- // In this case we are considering request_time that takes
- // into account the delay of the xbar, if any, and just
- // lat, neglecting responseLatency, modelling hit latency
- // just as lookupLatency or or the value of lat overriden
- // by access(), that calls accessBlock() function.
- cpuSidePort->schedTimingResp(pkt, request_time, true);
- } else {
- DPRINTF(Cache, "%s satisfied %s, no response needed\n", __func__,
- pkt->print());
-
- // queue the packet for deletion, as the sending cache is
- // still relying on it; if the block is found in access(),
- // CleanEvict and Writeback messages will be deleted
- // here as well
- pendingDelete.reset(pkt);
- }
+ BaseCache::handleTimingReqHit(pkt, blk, request_time);
}
void
Cache::handleTimingReqMiss(PacketPtr pkt, CacheBlk *blk, Tick forward_time,
Tick request_time)
{
+ if (pkt->req->isUncacheable()) {
+ // ignore any existing MSHR if we are dealing with an
+ // uncacheable request
+
+ // should have flushed and have no valid block
+ assert(!blk || !blk->isValid());
+
+ stats.cmdStats(pkt).mshrUncacheable[pkt->req->requestorId()]++;
+
+ if (pkt->isWrite()) {
+ allocateWriteBuffer(pkt, forward_time);
+ } else {
+ assert(pkt->isRead());
+
+ // uncacheable accesses always allocate a new MSHR
+
+ // Here we are using forward_time, modelling the latency of
+ // a miss (outbound) just as forwardLatency, neglecting the
+ // lookupLatency component.
+ allocateMissBuffer(pkt, forward_time);
+ }
+
+ return;
+ }
+
Addr blk_addr = pkt->getBlockAddr(blkSize);
- // ignore any existing MSHR if we are dealing with an
- // uncacheable request
- MSHR *mshr = pkt->req->isUncacheable() ? nullptr :
- mshrQueue.findMatch(blk_addr, pkt->isSecure());
+ MSHR *mshr = mshrQueue.findMatch(blk_addr, pkt->isSecure());
// Software prefetch handling:
// To keep the core from waiting on data it won't look at
if (!mshr) {
// copy the request and create a new SoftPFReq packet
- RequestPtr req = new Request(pkt->req->getPaddr(),
- pkt->req->getSize(),
- pkt->req->getFlags(),
- pkt->req->masterId());
+ RequestPtr req = std::make_shared<Request>(pkt->req->getPaddr(),
+ pkt->req->getSize(),
+ pkt->req->getFlags(),
+ pkt->req->requestorId());
pf = new Packet(req, pkt->cmd);
pf->allocate();
- assert(pf->getAddr() == pkt->getAddr());
+ assert(pf->matchAddr(pkt));
assert(pf->getSize() == pkt->getSize());
}
// request_time is used here, taking into account lat and the delay
// charged if the packet comes from the xbar.
- cpuSidePort->schedTimingResp(pkt, request_time, true);
+ cpuSidePort.schedTimingResp(pkt, request_time);
// If an outstanding request is in progress (we found an
// MSHR) this is set to null
pkt = pf;
}
- if (mshr) {
- /// MSHR hit
- /// @note writebacks will be checked in getNextMSHR()
- /// for any conflicting requests to the same block
-
- //@todo remove hw_pf here
-
- // Coalesce unless it was a software prefetch (see above).
- if (pkt) {
- assert(!pkt->isWriteback());
- // CleanEvicts corresponding to blocks which have
- // outstanding requests in MSHRs are simply sunk here
- if (pkt->cmd == MemCmd::CleanEvict) {
- pendingDelete.reset(pkt);
- } else if (pkt->cmd == MemCmd::WriteClean) {
- // A WriteClean should never coalesce with any
- // outstanding cache maintenance requests.
-
- // We use forward_time here because there is an
- // uncached memory write, forwarded to WriteBuffer.
- allocateWriteBuffer(pkt, forward_time);
- } else {
- DPRINTF(Cache, "%s coalescing MSHR for %s\n", __func__,
- pkt->print());
-
- assert(pkt->req->masterId() < system->maxMasters());
- mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
-
- // uncacheable accesses always allocate a new
- // MSHR, and cacheable accesses ignore any
- // uncacheable MSHRs, thus we should never have
- // targets addded if originally allocated
- // uncacheable
- assert(!mshr->isUncacheable());
-
- // We use forward_time here because it is the same
- // considering new targets. We have multiple
- // requests for the same address here. It
- // specifies the latency to allocate an internal
- // buffer and to schedule an event to the queued
- // port and also takes into account the additional
- // delay of the xbar.
- mshr->allocateTarget(pkt, forward_time, order++,
- allocOnFill(pkt->cmd));
- if (mshr->getNumTargets() == numTarget) {
- noTargetMSHR = mshr;
- setBlocked(Blocked_NoTargets);
- // need to be careful with this... if this mshr isn't
- // ready yet (i.e. time > curTick()), we don't want to
- // move it ahead of mshrs that are ready
- // mshrQueue.moveToFront(mshr);
- }
- }
- }
- } else {
- // no MSHR
- assert(pkt->req->masterId() < system->maxMasters());
- if (pkt->req->isUncacheable()) {
- mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++;
- } else {
- mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
- }
-
- if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean ||
- (pkt->req->isUncacheable() && pkt->isWrite())) {
- // We use forward_time here because there is an
- // uncached memory write, forwarded to WriteBuffer.
- allocateWriteBuffer(pkt, forward_time);
- } else {
- if (blk && blk->isValid()) {
- // should have flushed and have no valid block
- assert(!pkt->req->isUncacheable());
-
- // If we have a write miss to a valid block, we
- // need to mark the block non-readable. Otherwise
- // if we allow reads while there's an outstanding
- // write miss, the read could return stale data
- // out of the cache block... a more aggressive
- // system could detect the overlap (if any) and
- // forward data out of the MSHRs, but we don't do
- // that yet. Note that we do need to leave the
- // block valid so that it stays in the cache, in
- // case we get an upgrade response (and hence no
- // new data) when the write miss completes.
- // As long as CPUs do proper store/load forwarding
- // internally, and have a sufficiently weak memory
- // model, this is probably unnecessary, but at some
- // point it must have seemed like we needed it...
- assert((pkt->needsWritable() && !blk->isWritable()) ||
- pkt->req->isCacheMaintenance());
- blk->status &= ~BlkReadable;
- }
- // Here we are using forward_time, modelling the latency of
- // a miss (outbound) just as forwardLatency, neglecting the
- // lookupLatency component.
- allocateMissBuffer(pkt, forward_time);
- }
- }
+ BaseCache::handleTimingReqMiss(pkt, mshr, blk, forward_time, request_time);
}
void
{
DPRINTF(CacheTags, "%s tags:\n%s\n", __func__, tags->print());
- assert(pkt->isRequest());
-
- // Just forward the packet if caches are disabled.
- if (system->bypassCaches()) {
- // @todo This should really enqueue the packet rather
- bool M5_VAR_USED success = memSidePort->sendTimingReq(pkt);
- assert(success);
- return;
- }
-
promoteWholeLineWrites(pkt);
- // Cache maintenance operations have to visit all the caches down
- // to the specified xbar (PoC, PoU, etc.). Even if a cache above
- // is responding we forward the packet to the memory below rather
- // than creating an express snoop.
if (pkt->cacheResponding()) {
// a cache above us (but not where the packet came from) is
// responding to the request, in other words it has the line
// this express snoop travels towards the memory, and at
// every crossbar it is snooped upwards thus reaching
// every cache in the system
- bool M5_VAR_USED success = memSidePort->sendTimingReq(snoop_pkt);
+ M5_VAR_USED bool success = memSidePort.sendTimingReq(snoop_pkt);
// express snoops always succeed
assert(success);
return;
}
- // anything that is merely forwarded pays for the forward latency and
- // the delay provided by the crossbar
- Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
-
- // We use lookupLatency here because it is used to specify the latency
- // to access.
- Cycles lat = lookupLatency;
- CacheBlk *blk = nullptr;
- bool satisfied = false;
- {
- PacketList writebacks;
- // Note that lat is passed by reference here. The function
- // access() calls accessBlock() which can modify lat value.
- satisfied = access(pkt, blk, lat, writebacks);
-
- // copy writebacks to write buffer here to ensure they logically
- // proceed anything happening below
- doWritebacks(writebacks, forward_time);
- }
-
- // Here we charge the headerDelay that takes into account the latencies
- // of the bus, if the packet comes from it.
- // The latency charged it is just lat that is the value of lookupLatency
- // modified by access() function, or if not just lookupLatency.
- // In case of a hit we are neglecting response latency.
- // In case of a miss we are neglecting forward latency.
- Tick request_time = clockEdge(lat) + pkt->headerDelay;
- // Here we reset the timing of the packet.
- pkt->headerDelay = pkt->payloadDelay = 0;
-
- // track time of availability of next prefetch, if any
- Tick next_pf_time = MaxTick;
-
- if (satisfied) {
- // if need to notify the prefetcher we need to do it anything
- // else, handleTimingReqHit might turn the packet into a
- // response
- if (prefetcher &&
- (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
- if (blk)
- blk->status &= ~BlkHWPrefetched;
-
- // Don't notify on SWPrefetch
- if (!pkt->cmd.isSWPrefetch()) {
- assert(!pkt->req->isCacheMaintenance());
- next_pf_time = prefetcher->notify(pkt);
- }
- }
-
- handleTimingReqHit(pkt, blk, request_time);
- } else {
- handleTimingReqMiss(pkt, blk, forward_time, request_time);
-
- // We should call the prefetcher reguardless if the request is
- // satisfied or not, reguardless if the request is in the MSHR
- // or not. The request could be a ReadReq hit, but still not
- // satisfied (potentially because of a prior write to the same
- // cache line. So, even when not satisfied, there is an MSHR
- // already allocated for this, we need to let the prefetcher
- // know about the request
- if (prefetcher && pkt &&
- !pkt->cmd.isSWPrefetch() &&
- !pkt->req->isCacheMaintenance()) {
- next_pf_time = prefetcher->notify(pkt);
- }
- }
-
- if (next_pf_time != MaxTick)
- schedMemSideSendEvent(next_pf_time);
+ BaseCache::recvTimingReq(pkt);
}
PacketPtr
Cache::createMissPacket(PacketPtr cpu_pkt, CacheBlk *blk,
- bool needsWritable) const
+ bool needsWritable,
+ bool is_whole_line_write) const
{
// should never see evictions here
assert(!cpu_pkt->isEviction());
// write miss on a shared owned block will generate a ReadExcl,
// which will clobber the owned copy.
const bool useUpgrades = true;
- if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
- assert(!blkValid || !blk->isWritable());
+ assert(cpu_pkt->cmd != MemCmd::WriteLineReq || is_whole_line_write);
+ if (is_whole_line_write) {
+ assert(!blkValid || !blk->isSet(CacheBlk::WritableBit));
// forward as invalidate to all other caches, this gives us
// the line in Exclusive state, and invalidates all other
// copies
// only reason to be here is that blk is read only and we need
// it to be writable
assert(needsWritable);
- assert(!blk->isWritable());
+ assert(!blk->isSet(CacheBlk::WritableBit));
cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq;
} else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq ||
cpu_pkt->cmd == MemCmd::StoreCondFailReq) {
}
-Tick
-Cache::recvAtomic(PacketPtr pkt)
+Cycles
+Cache::handleAtomicReqMiss(PacketPtr pkt, CacheBlk *&blk,
+ PacketList &writebacks)
{
- // We are in atomic mode so we pay just for lookupLatency here.
- Cycles lat = lookupLatency;
-
- // Forward the request if the system is in cache bypass mode.
- if (system->bypassCaches())
- return ticksToCycles(memSidePort->sendAtomic(pkt));
+ // deal with the packets that go through the write path of
+ // the cache, i.e. any evictions and writes
+ if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean ||
+ (pkt->req->isUncacheable() && pkt->isWrite())) {
+ Cycles latency = ticksToCycles(memSidePort.sendAtomic(pkt));
- promoteWholeLineWrites(pkt);
-
- // follow the same flow as in recvTimingReq, and check if a cache
- // above us is responding
- if (pkt->cacheResponding() && !pkt->isClean()) {
- assert(!pkt->req->isCacheInvalidate());
- DPRINTF(Cache, "Cache above responding to %s: not responding\n",
- pkt->print());
-
- // if a cache is responding, and it had the line in Owned
- // rather than Modified state, we need to invalidate any
- // copies that are not on the same path to memory
- assert(pkt->needsWritable() && !pkt->responderHadWritable());
- lat += ticksToCycles(memSidePort->sendAtomic(pkt));
+ // at this point, if the request was an uncacheable write
+ // request, it has been satisfied by a memory below and the
+ // packet carries the response back
+ assert(!(pkt->req->isUncacheable() && pkt->isWrite()) ||
+ pkt->isResponse());
- return lat * clockPeriod();
+ return latency;
}
- // should assert here that there are no outstanding MSHRs or
- // writebacks... that would mean that someone used an atomic
- // access in timing mode
-
- CacheBlk *blk = nullptr;
- PacketList writebacks;
- bool satisfied = access(pkt, blk, lat, writebacks);
-
- if (pkt->isClean() && blk && blk->isDirty()) {
- // A cache clean opearation is looking for a dirty
- // block. If a dirty block is encountered a WriteClean
- // will update any copies to the path to the memory
- // until the point of reference.
- DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
- __func__, pkt->print(), blk->print());
- PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id);
- writebacks.push_back(wb_pkt);
- pkt->setSatisfied();
- }
-
- // handle writebacks resulting from the access here to ensure they
- // logically proceed anything happening below
- doWritebacksAtomic(writebacks);
-
- if (!satisfied) {
- // MISS
-
- // deal with the packets that go through the write path of
- // the cache, i.e. any evictions and writes
- if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean ||
- (pkt->req->isUncacheable() && pkt->isWrite())) {
- lat += ticksToCycles(memSidePort->sendAtomic(pkt));
- return lat * clockPeriod();
- }
- // only misses left
+ // only misses left
- PacketPtr bus_pkt = createMissPacket(pkt, blk, pkt->needsWritable());
+ PacketPtr bus_pkt = createMissPacket(pkt, blk, pkt->needsWritable(),
+ pkt->isWholeLineWrite(blkSize));
- bool is_forward = (bus_pkt == nullptr);
+ bool is_forward = (bus_pkt == nullptr);
- if (is_forward) {
- // just forwarding the same request to the next level
- // no local cache operation involved
- bus_pkt = pkt;
- }
+ if (is_forward) {
+ // just forwarding the same request to the next level
+ // no local cache operation involved
+ bus_pkt = pkt;
+ }
- DPRINTF(Cache, "%s: Sending an atomic %s\n", __func__,
- bus_pkt->print());
+ DPRINTF(Cache, "%s: Sending an atomic %s\n", __func__,
+ bus_pkt->print());
#if TRACING_ON
- CacheBlk::State old_state = blk ? blk->status : 0;
+ const std::string old_state = blk ? blk->print() : "";
#endif
- lat += ticksToCycles(memSidePort->sendAtomic(bus_pkt));
-
- bool is_invalidate = bus_pkt->isInvalidate();
-
- // We are now dealing with the response handling
- DPRINTF(Cache, "%s: Receive response: %s in state %i\n", __func__,
- bus_pkt->print(), old_state);
-
- // If packet was a forward, the response (if any) is already
- // in place in the bus_pkt == pkt structure, so we don't need
- // to do anything. Otherwise, use the separate bus_pkt to
- // generate response to pkt and then delete it.
- if (!is_forward) {
- if (pkt->needsResponse()) {
- assert(bus_pkt->isResponse());
- if (bus_pkt->isError()) {
- pkt->makeAtomicResponse();
- pkt->copyError(bus_pkt);
- } else if (pkt->cmd == MemCmd::WriteLineReq) {
- // note the use of pkt, not bus_pkt here.
-
- // write-line request to the cache that promoted
- // the write to a whole line
- blk = handleFill(pkt, blk, writebacks,
- allocOnFill(pkt->cmd));
- assert(blk != NULL);
- is_invalidate = false;
- satisfyRequest(pkt, blk);
- } else if (bus_pkt->isRead() ||
- bus_pkt->cmd == MemCmd::UpgradeResp) {
- // we're updating cache state to allow us to
- // satisfy the upstream request from the cache
- blk = handleFill(bus_pkt, blk, writebacks,
- allocOnFill(pkt->cmd));
- satisfyRequest(pkt, blk);
- maintainClusivity(pkt->fromCache(), blk);
- } else {
- // we're satisfying the upstream request without
- // modifying cache state, e.g., a write-through
- pkt->makeAtomicResponse();
- }
+ Cycles latency = ticksToCycles(memSidePort.sendAtomic(bus_pkt));
+
+ bool is_invalidate = bus_pkt->isInvalidate();
+
+ // We are now dealing with the response handling
+ DPRINTF(Cache, "%s: Receive response: %s for %s\n", __func__,
+ bus_pkt->print(), old_state);
+
+ // If packet was a forward, the response (if any) is already
+ // in place in the bus_pkt == pkt structure, so we don't need
+ // to do anything. Otherwise, use the separate bus_pkt to
+ // generate response to pkt and then delete it.
+ if (!is_forward) {
+ if (pkt->needsResponse()) {
+ assert(bus_pkt->isResponse());
+ if (bus_pkt->isError()) {
+ pkt->makeAtomicResponse();
+ pkt->copyError(bus_pkt);
+ } else if (pkt->isWholeLineWrite(blkSize)) {
+ // note the use of pkt, not bus_pkt here.
+
+ // write-line request to the cache that promoted
+ // the write to a whole line
+ const bool allocate = allocOnFill(pkt->cmd) &&
+ (!writeAllocator || writeAllocator->allocate());
+ blk = handleFill(bus_pkt, blk, writebacks, allocate);
+ assert(blk != NULL);
+ is_invalidate = false;
+ satisfyRequest(pkt, blk);
+ } else if (bus_pkt->isRead() ||
+ bus_pkt->cmd == MemCmd::UpgradeResp) {
+ // we're updating cache state to allow us to
+ // satisfy the upstream request from the cache
+ blk = handleFill(bus_pkt, blk, writebacks,
+ allocOnFill(pkt->cmd));
+ satisfyRequest(pkt, blk);
+ maintainClusivity(pkt->fromCache(), blk);
+ } else {
+ // we're satisfying the upstream request without
+ // modifying cache state, e.g., a write-through
+ pkt->makeAtomicResponse();
}
- delete bus_pkt;
- }
-
- if (is_invalidate && blk && blk->isValid()) {
- invalidateBlock(blk);
}
+ delete bus_pkt;
}
- // Note that we don't invoke the prefetcher at all in atomic mode.
- // It's not clear how to do it properly, particularly for
- // prefetchers that aggressively generate prefetch candidates and
- // rely on bandwidth contention to throttle them; these will tend
- // to pollute the cache in atomic mode since there is no bandwidth
- // contention. If we ever do want to enable prefetching in atomic
- // mode, though, this is the place to do it... see timingAccess()
- // for an example (though we'd want to issue the prefetch(es)
- // immediately rather than calling requestMemSideBus() as we do
- // there).
-
- // do any writebacks resulting from the response handling
- doWritebacksAtomic(writebacks);
-
- // if we used temp block, check to see if its valid and if so
- // clear it out, but only do so after the call to recvAtomic is
- // finished so that any downstream observers (such as a snoop
- // filter), first see the fill, and only then see the eviction
- if (blk == tempBlock && tempBlock->isValid()) {
- // the atomic CPU calls recvAtomic for fetch and load/store
- // sequentuially, and we may already have a tempBlock
- // writeback from the fetch that we have not yet sent
- if (tempBlockWriteback) {
- // if that is the case, write the prevoius one back, and
- // do not schedule any new event
- writebackTempBlockAtomic();
- } else {
- // the writeback/clean eviction happens after the call to
- // recvAtomic has finished (but before any successive
- // calls), so that the response handling from the fill is
- // allowed to happen first
- schedule(writebackTempBlockAtomicEvent, curTick());
- }
-
- tempBlockWriteback = (blk->isDirty() || writebackClean) ?
- writebackBlk(blk) : cleanEvictBlk(blk);
+ if (is_invalidate && blk && blk->isValid()) {
invalidateBlock(blk);
}
- if (pkt->needsResponse()) {
- pkt->makeAtomicResponse();
- }
-
- return lat * clockPeriod();
+ return latency;
}
-
-void
-Cache::functionalAccess(PacketPtr pkt, bool fromCpuSide)
+Tick
+Cache::recvAtomic(PacketPtr pkt)
{
- if (system->bypassCaches()) {
- // Packets from the memory side are snoop request and
- // shouldn't happen in bypass mode.
- assert(fromCpuSide);
-
- // The cache should be flushed if we are in cache bypass mode,
- // so we don't need to check if we need to update anything.
- memSidePort->sendFunctional(pkt);
- return;
- }
-
- Addr blk_addr = pkt->getBlockAddr(blkSize);
- bool is_secure = pkt->isSecure();
- CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
- MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
-
- pkt->pushLabel(name());
-
- CacheBlkPrintWrapper cbpw(blk);
-
- // Note that just because an L2/L3 has valid data doesn't mean an
- // L1 doesn't have a more up-to-date modified copy that still
- // needs to be found. As a result we always update the request if
- // we have it, but only declare it satisfied if we are the owner.
-
- // see if we have data at all (owned or otherwise)
- bool have_data = blk && blk->isValid()
- && pkt->checkFunctional(&cbpw, blk_addr, is_secure, blkSize,
- blk->data);
-
- // data we have is dirty if marked as such or if we have an
- // in-service MSHR that is pending a modified line
- bool have_dirty =
- have_data && (blk->isDirty() ||
- (mshr && mshr->inService && mshr->isPendingModified()));
-
- bool done = have_dirty
- || cpuSidePort->checkFunctional(pkt)
- || mshrQueue.checkFunctional(pkt, blk_addr)
- || writeBuffer.checkFunctional(pkt, blk_addr)
- || memSidePort->checkFunctional(pkt);
+ promoteWholeLineWrites(pkt);
- DPRINTF(CacheVerbose, "%s: %s %s%s%s\n", __func__, pkt->print(),
- (blk && blk->isValid()) ? "valid " : "",
- have_data ? "data " : "", done ? "done " : "");
+ // follow the same flow as in recvTimingReq, and check if a cache
+ // above us is responding
+ if (pkt->cacheResponding()) {
+ assert(!pkt->req->isCacheInvalidate());
+ DPRINTF(Cache, "Cache above responding to %s: not responding\n",
+ pkt->print());
- // We're leaving the cache, so pop cache->name() label
- pkt->popLabel();
+ // if a cache is responding, and it had the line in Owned
+ // rather than Modified state, we need to invalidate any
+ // copies that are not on the same path to memory
+ assert(pkt->needsWritable() && !pkt->responderHadWritable());
- if (done) {
- pkt->makeResponse();
- } else {
- // if it came as a request from the CPU side then make sure it
- // continues towards the memory side
- if (fromCpuSide) {
- memSidePort->sendFunctional(pkt);
- } else if (cpuSidePort->isSnooping()) {
- // if it came from the memory side, it must be a snoop request
- // and we should only forward it if we are forwarding snoops
- cpuSidePort->sendFunctionalSnoop(pkt);
- }
+ return memSidePort.sendAtomic(pkt);
}
+
+ return BaseCache::recvAtomic(pkt);
}
void
-Cache::handleUncacheableWriteResp(PacketPtr pkt)
-{
- Tick completion_time = clockEdge(responseLatency) +
- pkt->headerDelay + pkt->payloadDelay;
-
- // Reset the bus additional time as it is now accounted for
- pkt->headerDelay = pkt->payloadDelay = 0;
-
- cpuSidePort->schedTimingResp(pkt, completion_time, true);
-}
-
-void
-Cache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk,
- PacketList &writebacks)
+Cache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk)
{
- MSHR::Target *initial_tgt = mshr->getTarget();
+ QueueEntry::Target *initial_tgt = mshr->getTarget();
// First offset for critical word first calculations
const int initial_offset = initial_tgt->pkt->getOffset(blkSize);
const bool is_error = pkt->isError();
- bool is_fill = !mshr->isForward &&
- (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
// allow invalidation responses originating from write-line
// requests to be discarded
- bool is_invalidate = pkt->isInvalidate();
+ bool is_invalidate = pkt->isInvalidate() &&
+ !mshr->wasWholeLineWrite;
MSHR::TargetList targets = mshr->extractServiceableTargets(pkt);
for (auto &target: targets) {
// Software prefetch handling for cache closest to core
if (tgt_pkt->cmd.isSWPrefetch()) {
+ if (tgt_pkt->needsWritable()) {
+ // All other copies of the block were invalidated and we
+ // have an exclusive copy.
+
+ // The coherence protocol assumes that if we fetched an
+ // exclusive copy of the block, we have the intention to
+ // modify it. Therefore the MSHR for the PrefetchExReq has
+ // been the point of ordering and this cache has commited
+ // to respond to snoops for the block.
+ //
+ // In most cases this is true anyway - a PrefetchExReq
+ // will be followed by a WriteReq. However, if that
+ // doesn't happen, the block is not marked as dirty and
+ // the cache doesn't respond to snoops that has committed
+ // to do so.
+ //
+ // To avoid deadlocks in cases where there is a snoop
+ // between the PrefetchExReq and the expected WriteReq, we
+ // proactively mark the block as Dirty.
+ assert(blk);
+ blk->setCoherenceBits(CacheBlk::DirtyBit);
+
+ panic_if(isReadOnly, "Prefetch exclusive requests from "
+ "read-only cache %s\n", name());
+ }
+
// a software prefetch would have already been ack'd
// immediately with dummy data so the core would be able to
// retire it. This request completes right here, so we
// deallocate it.
- delete tgt_pkt->req;
delete tgt_pkt;
break; // skip response
}
// from above.
if (tgt_pkt->cmd == MemCmd::WriteLineReq) {
assert(!is_error);
- // we got the block in a writable state, so promote
- // any deferred targets if possible
- mshr->promoteWritable();
- // NB: we use the original packet here and not the response!
- blk = handleFill(tgt_pkt, blk, writebacks,
- targets.allocOnFill);
assert(blk);
-
- // treat as a fill, and discard the invalidation
- // response
- is_fill = true;
- is_invalidate = false;
+ assert(blk->isSet(CacheBlk::WritableBit));
}
- if (is_fill) {
+ // Here we decide whether we will satisfy the target using
+ // data from the block or from the response. We use the
+ // block data to satisfy the request when the block is
+ // present and valid and in addition the response in not
+ // forwarding data to the cache above (we didn't fill
+ // either); otherwise we use the packet data.
+ if (blk && blk->isValid() &&
+ (!mshr->isForward || !pkt->hasData())) {
satisfyRequest(tgt_pkt, blk, true, mshr->hasPostDowngrade());
// How many bytes past the first request is this one
assert(!tgt_pkt->req->isUncacheable());
- assert(tgt_pkt->req->masterId() < system->maxMasters());
- missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] +=
+ assert(tgt_pkt->req->requestorId() < system->maxRequestors());
+ stats.cmdStats(tgt_pkt)
+ .missLatency[tgt_pkt->req->requestorId()] +=
completion_time - target.recvTime;
} else if (pkt->cmd == MemCmd::UpgradeFailResp) {
// failed StoreCond upgrade
pkt->payloadDelay;
tgt_pkt->req->setExtraData(0);
} else {
- // We are about to send a response to a cache above
- // that asked for an invalidation; we need to
- // invalidate our copy immediately as the most
- // up-to-date copy of the block will now be in the
- // cache above. It will also prevent this cache from
- // responding (if the block was previously dirty) to
- // snoops as they should snoop the caches above where
- // they will get the response from.
if (is_invalidate && blk && blk->isValid()) {
+ // We are about to send a response to a cache above
+ // that asked for an invalidation; we need to
+ // invalidate our copy immediately as the most
+ // up-to-date copy of the block will now be in the
+ // cache above. It will also prevent this cache from
+ // responding (if the block was previously dirty) to
+ // snoops as they should snoop the caches above where
+ // they will get the response from.
invalidateBlock(blk);
}
// not a cache fill, just forwarding response
// from lower level cahces/memory to the core.
completion_time += clockEdge(responseLatency) +
pkt->payloadDelay;
- if (pkt->isRead() && !is_error) {
- // sanity check
- assert(pkt->getAddr() == tgt_pkt->getAddr());
- assert(pkt->getSize() >= tgt_pkt->getSize());
+ if (!is_error) {
+ if (pkt->isRead()) {
+ // sanity check
+ assert(pkt->matchAddr(tgt_pkt));
+ assert(pkt->getSize() >= tgt_pkt->getSize());
- tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
+ tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
+ } else {
+ // MSHR targets can read data either from the
+ // block or the response pkt. If we can't get data
+ // from the block (i.e., invalid or has old data)
+ // or the response (did not bring in any data)
+ // then make sure that the target didn't expect
+ // any.
+ assert(!tgt_pkt->hasRespData());
+ }
}
+
+ // this response did not allocate here and therefore
+ // it was not consumed, make sure that any flags are
+ // carried over to cache above
+ tgt_pkt->copyResponderFlags(pkt);
}
tgt_pkt->makeTimingResponse();
// if this packet is an error copy that to the new packet
}
// Reset the bus additional time as it is now accounted for
tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0;
- cpuSidePort->schedTimingResp(tgt_pkt, completion_time, true);
+ cpuSidePort.schedTimingResp(tgt_pkt, completion_time);
break;
case MSHR::Target::FromPrefetcher:
assert(tgt_pkt->cmd == MemCmd::HardPFReq);
if (blk)
- blk->status |= BlkHWPrefetched;
- delete tgt_pkt->req;
+ blk->setPrefetched();
delete tgt_pkt;
break;
if (is_invalidate || mshr->hasPostInvalidate()) {
invalidateBlock(blk);
} else if (mshr->hasPostDowngrade()) {
- blk->status &= ~BlkWritable;
+ blk->clearCoherenceBits(CacheBlk::WritableBit);
}
}
}
-void
-Cache::recvTimingResp(PacketPtr pkt)
+PacketPtr
+Cache::evictBlock(CacheBlk *blk)
{
- assert(pkt->isResponse());
-
- // all header delay should be paid for by the crossbar, unless
- // this is a prefetch response from above
- panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
- "%s saw a non-zero packet delay\n", name());
-
- const bool is_error = pkt->isError();
+ PacketPtr pkt = (blk->isSet(CacheBlk::DirtyBit) || writebackClean) ?
+ writebackBlk(blk) : cleanEvictBlk(blk);
- if (is_error) {
- DPRINTF(Cache, "%s: Cache received %s with error\n", __func__,
- pkt->print());
- }
-
- DPRINTF(Cache, "%s: Handling response %s\n", __func__,
- pkt->print());
-
- // if this is a write, we should be looking at an uncacheable
- // write
- if (pkt->isWrite()) {
- assert(pkt->req->isUncacheable());
- handleUncacheableWriteResp(pkt);
- return;
- }
+ invalidateBlock(blk);
- // we have dealt with any (uncacheable) writes above, from here on
- // we know we are dealing with an MSHR due to a miss or a prefetch
- MSHR *mshr = dynamic_cast<MSHR*>(pkt->popSenderState());
- assert(mshr);
+ return pkt;
+}
- if (mshr == noTargetMSHR) {
- // we always clear at least one target
- clearBlocked(Blocked_NoTargets);
- noTargetMSHR = nullptr;
- }
+PacketPtr
+Cache::cleanEvictBlk(CacheBlk *blk)
+{
+ assert(!writebackClean);
+ assert(blk && blk->isValid() && !blk->isSet(CacheBlk::DirtyBit));
- // Initial target is used just for stats
- MSHR::Target *initial_tgt = mshr->getTarget();
- int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
- Tick miss_latency = curTick() - initial_tgt->recvTime;
+ // Creating a zero sized write, a message to the snoop filter
+ RequestPtr req = std::make_shared<Request>(
+ regenerateBlkAddr(blk), blkSize, 0, Request::wbRequestorId);
- if (pkt->req->isUncacheable()) {
- assert(pkt->req->masterId() < system->maxMasters());
- mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
- miss_latency;
- } else {
- assert(pkt->req->masterId() < system->maxMasters());
- mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
- miss_latency;
- }
+ if (blk->isSecure())
+ req->setFlags(Request::SECURE);
- PacketList writebacks;
+ req->taskId(blk->getTaskId());
- bool is_fill = !mshr->isForward &&
- (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
+ PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
+ pkt->allocate();
+ DPRINTF(Cache, "Create CleanEvict %s\n", pkt->print());
- CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
+ return pkt;
+}
- if (is_fill && !is_error) {
- DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
- pkt->getAddr());
-
- blk = handleFill(pkt, blk, writebacks, mshr->allocOnFill());
- assert(blk != nullptr);
- }
-
- if (blk && blk->isValid() && pkt->isClean() && !pkt->isInvalidate()) {
- // The block was marked not readable while there was a pending
- // cache maintenance operation, restore its flag.
- blk->status |= BlkReadable;
- }
-
- if (blk && blk->isWritable() && !pkt->req->isCacheInvalidate()) {
- // If at this point the referenced block is writable and the
- // response is not a cache invalidate, we promote targets that
- // were deferred as we couldn't guarrantee a writable copy
- mshr->promoteWritable();
- }
-
- serviceMSHRTargets(mshr, pkt, blk, writebacks);
-
- if (mshr->promoteDeferredTargets()) {
- // avoid later read getting stale data while write miss is
- // outstanding.. see comment in timingAccess()
- if (blk) {
- blk->status &= ~BlkReadable;
- }
- mshrQueue.markPending(mshr);
- schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
- } else {
- // while we deallocate an mshr from the queue we still have to
- // check the isFull condition before and after as we might
- // have been using the reserved entries already
- const bool was_full = mshrQueue.isFull();
- mshrQueue.deallocate(mshr);
- if (was_full && !mshrQueue.isFull()) {
- clearBlocked(Blocked_NoMSHRs);
- }
-
- // Request the bus for a prefetch if this deallocation freed enough
- // MSHRs for a prefetch to take place
- if (prefetcher && mshrQueue.canPrefetch()) {
- Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
- clockEdge());
- if (next_pf_time != MaxTick)
- schedMemSideSendEvent(next_pf_time);
- }
- }
-
- // if we used temp block, check to see if its valid and then clear it out
- if (blk == tempBlock && tempBlock->isValid()) {
- PacketPtr wb_pkt = tempBlock->isDirty() || writebackClean ?
- writebackBlk(blk) : cleanEvictBlk(blk);
- writebacks.push_back(wb_pkt);
- invalidateBlock(tempBlock);
- }
-
- const Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
- // copy writebacks to write buffer
- doWritebacks(writebacks, forward_time);
-
- DPRINTF(CacheVerbose, "%s: Leaving with %s\n", __func__, pkt->print());
- delete pkt;
-}
-
-PacketPtr
-Cache::writebackBlk(CacheBlk *blk)
-{
- chatty_assert(!isReadOnly || writebackClean,
- "Writeback from read-only cache");
- assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
-
- writebacks[Request::wbMasterId]++;
-
- Request *req = new Request(tags->regenerateBlkAddr(blk), blkSize, 0,
- Request::wbMasterId);
- if (blk->isSecure())
- req->setFlags(Request::SECURE);
-
- req->taskId(blk->task_id);
-
- PacketPtr pkt =
- new Packet(req, blk->isDirty() ?
- MemCmd::WritebackDirty : MemCmd::WritebackClean);
-
- DPRINTF(Cache, "Create Writeback %s writable: %d, dirty: %d\n",
- pkt->print(), blk->isWritable(), blk->isDirty());
-
- if (blk->isWritable()) {
- // not asserting shared means we pass the block in modified
- // state, mark our own block non-writeable
- blk->status &= ~BlkWritable;
- } else {
- // we are in the Owned state, tell the receiver
- pkt->setHasSharers();
- }
-
- // make sure the block is not marked dirty
- blk->status &= ~BlkDirty;
-
- pkt->allocate();
- pkt->setDataFromBlock(blk->data, blkSize);
-
- return pkt;
-}
-
-PacketPtr
-Cache::writecleanBlk(CacheBlk *blk, Request::Flags dest, PacketId id)
-{
- Request *req = new Request(tags->regenerateBlkAddr(blk), blkSize, 0,
- Request::wbMasterId);
- if (blk->isSecure()) {
- req->setFlags(Request::SECURE);
- }
- req->taskId(blk->task_id);
-
- PacketPtr pkt = new Packet(req, MemCmd::WriteClean, blkSize, id);
-
- if (dest) {
- req->setFlags(dest);
- pkt->setWriteThrough();
- }
-
- DPRINTF(Cache, "Create %s writable: %d, dirty: %d\n", pkt->print(),
- blk->isWritable(), blk->isDirty());
-
- if (blk->isWritable()) {
- // not asserting shared means we pass the block in modified
- // state, mark our own block non-writeable
- blk->status &= ~BlkWritable;
- } else {
- // we are in the Owned state, tell the receiver
- pkt->setHasSharers();
- }
-
- // make sure the block is not marked dirty
- blk->status &= ~BlkDirty;
-
- pkt->allocate();
- pkt->setDataFromBlock(blk->data, blkSize);
-
- return pkt;
-}
-
-
-PacketPtr
-Cache::cleanEvictBlk(CacheBlk *blk)
-{
- assert(!writebackClean);
- assert(blk && blk->isValid() && !blk->isDirty());
- // Creating a zero sized write, a message to the snoop filter
- Request *req =
- new Request(tags->regenerateBlkAddr(blk), blkSize, 0,
- Request::wbMasterId);
- if (blk->isSecure())
- req->setFlags(Request::SECURE);
-
- req->taskId(blk->task_id);
-
- PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
- pkt->allocate();
- DPRINTF(Cache, "Create CleanEvict %s\n", pkt->print());
-
- return pkt;
-}
-
-void
-Cache::memWriteback()
-{
- CacheBlkVisitorWrapper visitor(*this, &Cache::writebackVisitor);
- tags->forEachBlk(visitor);
-}
-
-void
-Cache::memInvalidate()
-{
- CacheBlkVisitorWrapper visitor(*this, &Cache::invalidateVisitor);
- tags->forEachBlk(visitor);
-}
-
-bool
-Cache::isDirty() const
-{
- CacheBlkIsDirtyVisitor visitor;
- tags->forEachBlk(visitor);
-
- return visitor.isDirty();
-}
-
-bool
-Cache::writebackVisitor(CacheBlk &blk)
-{
- if (blk.isDirty()) {
- assert(blk.isValid());
-
- Request request(tags->regenerateBlkAddr(&blk), blkSize, 0,
- Request::funcMasterId);
- request.taskId(blk.task_id);
- if (blk.isSecure()) {
- request.setFlags(Request::SECURE);
- }
-
- Packet packet(&request, MemCmd::WriteReq);
- packet.dataStatic(blk.data);
-
- memSidePort->sendFunctional(&packet);
-
- blk.status &= ~BlkDirty;
- }
-
- return true;
-}
-
-bool
-Cache::invalidateVisitor(CacheBlk &blk)
-{
-
- if (blk.isDirty())
- warn_once("Invalidating dirty cache lines. Expect things to break.\n");
-
- if (blk.isValid()) {
- assert(!blk.isDirty());
- invalidateBlock(&blk);
- }
-
- return true;
-}
-
-CacheBlk*
-Cache::allocateBlock(Addr addr, bool is_secure, PacketList &writebacks)
-{
- // Find replacement victim
- CacheBlk *blk = tags->findVictim(addr);
-
- // It is valid to return nullptr if there is no victim
- if (!blk)
- return nullptr;
-
- if (blk->isValid()) {
- Addr repl_addr = tags->regenerateBlkAddr(blk);
- MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
- if (repl_mshr) {
- // must be an outstanding upgrade or clean request
- // on a block we're about to replace...
- assert((!blk->isWritable() && repl_mshr->needsWritable()) ||
- repl_mshr->isCleaning());
- // too hard to replace block with transient state
- // allocation failed, block not inserted
- return nullptr;
- } else {
- DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx "
- "(%s): %s\n", repl_addr, blk->isSecure() ? "s" : "ns",
- addr, is_secure ? "s" : "ns",
- blk->isDirty() ? "writeback" : "clean");
-
- if (blk->wasPrefetched()) {
- unusedPrefetches++;
- }
- // Will send up Writeback/CleanEvict snoops via isCachedAbove
- // when pushing this writeback list into the write buffer.
- if (blk->isDirty() || writebackClean) {
- // Save writeback packet for handling by caller
- writebacks.push_back(writebackBlk(blk));
- } else {
- writebacks.push_back(cleanEvictBlk(blk));
- }
- replacements++;
- }
- }
-
- return blk;
-}
-
-void
-Cache::invalidateBlock(CacheBlk *blk)
-{
- if (blk != tempBlock)
- tags->invalidate(blk);
- blk->invalidate();
-}
-
-// Note that the reason we return a list of writebacks rather than
-// inserting them directly in the write buffer is that this function
-// is called by both atomic and timing-mode accesses, and in atomic
-// mode we don't mess with the write buffer (we just perform the
-// writebacks atomically once the original request is complete).
-CacheBlk*
-Cache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
- bool allocate)
-{
- assert(pkt->isResponse() || pkt->cmd == MemCmd::WriteLineReq);
- Addr addr = pkt->getAddr();
- bool is_secure = pkt->isSecure();
-#if TRACING_ON
- CacheBlk::State old_state = blk ? blk->status : 0;
-#endif
-
- // When handling a fill, we should have no writes to this line.
- assert(addr == pkt->getBlockAddr(blkSize));
- assert(!writeBuffer.findMatch(addr, is_secure));
-
- if (blk == nullptr) {
- // better have read new data...
- assert(pkt->hasData());
-
- // only read responses and write-line requests have data;
- // note that we don't write the data here for write-line - that
- // happens in the subsequent call to satisfyRequest
- assert(pkt->isRead() || pkt->cmd == MemCmd::WriteLineReq);
-
- // need to do a replacement if allocating, otherwise we stick
- // with the temporary storage
- blk = allocate ? allocateBlock(addr, is_secure, writebacks) : nullptr;
-
- if (blk == nullptr) {
- // No replaceable block or a mostly exclusive
- // cache... just use temporary storage to complete the
- // current request and then get rid of it
- assert(!tempBlock->isValid());
- blk = tempBlock;
- tempBlock->set = tags->extractSet(addr);
- tempBlock->tag = tags->extractTag(addr);
- if (is_secure) {
- tempBlock->status |= BlkSecure;
- }
- DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
- is_secure ? "s" : "ns");
- } else {
- tags->insertBlock(pkt, blk);
- }
-
- // we should never be overwriting a valid block
- assert(!blk->isValid());
- } else {
- // existing block... probably an upgrade
- assert(blk->tag == tags->extractTag(addr));
- // either we're getting new data or the block should already be valid
- assert(pkt->hasData() || blk->isValid());
- // don't clear block status... if block is already dirty we
- // don't want to lose that
- }
-
- if (is_secure)
- blk->status |= BlkSecure;
- blk->status |= BlkValid | BlkReadable;
-
- // sanity check for whole-line writes, which should always be
- // marked as writable as part of the fill, and then later marked
- // dirty as part of satisfyRequest
- if (pkt->cmd == MemCmd::WriteLineReq) {
- assert(!pkt->hasSharers());
- }
-
- // here we deal with setting the appropriate state of the line,
- // and we start by looking at the hasSharers flag, and ignore the
- // cacheResponding flag (normally signalling dirty data) if the
- // packet has sharers, thus the line is never allocated as Owned
- // (dirty but not writable), and always ends up being either
- // Shared, Exclusive or Modified, see Packet::setCacheResponding
- // for more details
- if (!pkt->hasSharers()) {
- // we could get a writable line from memory (rather than a
- // cache) even in a read-only cache, note that we set this bit
- // even for a read-only cache, possibly revisit this decision
- blk->status |= BlkWritable;
-
- // check if we got this via cache-to-cache transfer (i.e., from a
- // cache that had the block in Modified or Owned state)
- if (pkt->cacheResponding()) {
- // we got the block in Modified state, and invalidated the
- // owners copy
- blk->status |= BlkDirty;
-
- chatty_assert(!isReadOnly, "Should never see dirty snoop response "
- "in read-only cache %s\n", name());
- }
- }
-
- DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
- addr, is_secure ? "s" : "ns", old_state, blk->print());
-
- // if we got new data, copy it in (checking for a read response
- // and a response that has data is the same in the end)
- if (pkt->isRead()) {
- // sanity checks
- assert(pkt->hasData());
- assert(pkt->getSize() == blkSize);
-
- pkt->writeDataToBlock(blk->data, blkSize);
- }
- // We pay for fillLatency here.
- blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
- pkt->payloadDelay;
-
- return blk;
-}
-
-
-/////////////////////////////////////////////////////
-//
-// Snoop path: requests coming in from the memory side
-//
-/////////////////////////////////////////////////////
+/////////////////////////////////////////////////////
+//
+// Snoop path: requests coming in from the memory side
+//
+/////////////////////////////////////////////////////
void
Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data,
pkt->headerDelay = pkt->payloadDelay = 0;
DPRINTF(CacheVerbose, "%s: created response: %s tick: %lu\n", __func__,
pkt->print(), forward_time);
- memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
+ memSidePort.schedTimingSnoopResp(pkt, forward_time);
}
uint32_t
// responds in atomic mode, so remember a few things about the
// original packet up front
bool invalidate = pkt->isInvalidate();
- bool M5_VAR_USED needs_writable = pkt->needsWritable();
+ M5_VAR_USED bool needs_writable = pkt->needsWritable();
// at the moment we could get an uncacheable write which does not
// have the invalidate flag, and we need a suitable way of dealing
if (forwardSnoops) {
// first propagate snoop upward to see if anyone above us wants to
// handle it. save & restore packet src since it will get
- // rewritten to be relative to cpu-side bus (if any)
- bool alreadyResponded = pkt->cacheResponding();
+ // rewritten to be relative to CPU-side bus (if any)
if (is_timing) {
// copy the packet so that we can clear any flags before
// forwarding it upwards, we also allocate data (passing
// the snoop packet does not need to wait any additional
// time
snoopPkt.headerDelay = snoopPkt.payloadDelay = 0;
- cpuSidePort->sendTimingSnoopReq(&snoopPkt);
+ cpuSidePort.sendTimingSnoopReq(&snoopPkt);
// add the header delay (including crossbar and snoop
// delays) of the upward snoop to the snoop delay for this
// cache
snoop_delay += snoopPkt.headerDelay;
- if (snoopPkt.cacheResponding()) {
- // cache-to-cache response from some upper cache
- assert(!alreadyResponded);
- pkt->setCacheResponding();
- }
- // upstream cache has the block, or has an outstanding
- // MSHR, pass the flag on
- if (snoopPkt.hasSharers()) {
- pkt->setHasSharers();
- }
// If this request is a prefetch or clean evict and an upper level
// signals block present, make sure to propagate the block
- // presence to the requester.
+ // presence to the requestor.
if (snoopPkt.isBlockCached()) {
pkt->setBlockCached();
}
if (snoopPkt.satisfied()) {
pkt->setSatisfied();
}
+
+ // Copy over flags from the snoop response to make sure we
+ // inform the final destination
+ pkt->copyResponderFlags(&snoopPkt);
} else {
- cpuSidePort->sendAtomicSnoop(pkt);
- if (!alreadyResponded && pkt->cacheResponding()) {
+ bool already_responded = pkt->cacheResponding();
+ cpuSidePort.sendAtomicSnoop(pkt);
+ if (!already_responded && pkt->cacheResponding()) {
// cache-to-cache response from some upper cache:
- // forward response to original requester
+ // forward response to original requestor
assert(pkt->isResponse());
}
}
bool respond = false;
bool blk_valid = blk && blk->isValid();
if (pkt->isClean()) {
- if (blk_valid && blk->isDirty()) {
+ if (blk_valid && blk->isSet(CacheBlk::DirtyBit)) {
DPRINTF(CacheVerbose, "%s: packet (snoop) %s found block: %s\n",
__func__, pkt->print(), blk->print());
- PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id);
+ PacketPtr wb_pkt =
+ writecleanBlk(blk, pkt->req->getDest(), pkt->id);
PacketList writebacks;
writebacks.push_back(wb_pkt);
// invalidation itself is taken care of below. We don't respond to
// cache maintenance operations as this is done by the destination
// xbar.
- respond = blk->isDirty() && pkt->needsResponse();
+ respond = blk->isSet(CacheBlk::DirtyBit) && pkt->needsResponse();
- chatty_assert(!(isReadOnly && blk->isDirty()), "Should never have "
- "a dirty block in a read-only cache %s\n", name());
+ chatty_assert(!(isReadOnly && blk->isSet(CacheBlk::DirtyBit)),
+ "Should never have a dirty block in a read-only cache %s\n",
+ name());
}
// Invalidate any prefetch's from below that would strip write permissions
// which means we go from Modified to Owned (and will respond
// below), remain in Owned (and will respond below), from
// Exclusive to Shared, or remain in Shared
- if (!pkt->req->isUncacheable())
- blk->status &= ~BlkWritable;
+ if (!pkt->req->isUncacheable()) {
+ blk->clearCoherenceBits(CacheBlk::WritableBit);
+ }
DPRINTF(Cache, "new state is %s\n", blk->print());
}
// memory, and also prevent any memory from even seeing the
// request
pkt->setCacheResponding();
- if (!pkt->isClean() && blk->isWritable()) {
+ if (!pkt->isClean() && blk->isSet(CacheBlk::WritableBit)) {
// inform the cache hierarchy that this cache had the line
// in the Modified state so that we avoid unnecessary
// invalidations (see Packet::setResponderHadWritable)
if (pkt->hasData())
pkt->setDataFromBlock(blk->data, blkSize);
}
+
+ // When a block is compressed, it must first be decompressed before
+ // being read, and this increases the snoop delay.
+ if (compressor && pkt->isRead()) {
+ snoop_delay += compressor->getDecompressionLatency(blk);
+ }
}
if (!respond && is_deferred) {
assert(pkt->needsResponse());
-
- // if we copied the deferred packet with the intention to
- // respond, but are not responding, then a cache above us must
- // be, and we can use this as the indication of whether this
- // is a packet where we created a copy of the request or not
- if (!pkt->cacheResponding()) {
- delete pkt->req;
- }
-
delete pkt;
}
{
DPRINTF(CacheVerbose, "%s: for %s\n", __func__, pkt->print());
- // Snoops shouldn't happen when bypassing caches
- assert(!system->bypassCaches());
-
// no need to snoop requests that are not in range
if (!inRange(pkt->getAddr())) {
return;
return;
}
- // Bypass any existing cache maintenance requests if the request
- // has been satisfied already (i.e., the dirty block has been
- // found).
- if (mshr && pkt->req->isCacheMaintenance() && pkt->satisfied()) {
- return;
- }
-
// Let the MSHR itself track the snoop and decide whether we want
// to go ahead and do the regular cache snoop
if (mshr && mshr->handleSnoop(pkt, order++)) {
lookupLatency * clockPeriod());
}
-bool
-Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
-{
- // Express snoop responses from master to slave, e.g., from L1 to L2
- cache->recvTimingSnoopResp(pkt);
- return true;
-}
-
Tick
Cache::recvAtomicSnoop(PacketPtr pkt)
{
- // Snoops shouldn't happen when bypassing caches
- assert(!system->bypassCaches());
-
// no need to snoop requests that are not in range.
if (!inRange(pkt->getAddr())) {
return 0;
return snoop_delay + lookupLatency * clockPeriod();
}
-
-QueueEntry*
-Cache::getNextQueueEntry()
-{
- // Check both MSHR queue and write buffer for potential requests,
- // note that null does not mean there is no request, it could
- // simply be that it is not ready
- MSHR *miss_mshr = mshrQueue.getNext();
- WriteQueueEntry *wq_entry = writeBuffer.getNext();
-
- // If we got a write buffer request ready, first priority is a
- // full write buffer, otherwise we favour the miss requests
- if (wq_entry && (writeBuffer.isFull() || !miss_mshr)) {
- // need to search MSHR queue for conflicting earlier miss.
- MSHR *conflict_mshr =
- mshrQueue.findPending(wq_entry->blkAddr,
- wq_entry->isSecure);
-
- if (conflict_mshr && conflict_mshr->order < wq_entry->order) {
- // Service misses in order until conflict is cleared.
- return conflict_mshr;
-
- // @todo Note that we ignore the ready time of the conflict here
- }
-
- // No conflicts; issue write
- return wq_entry;
- } else if (miss_mshr) {
- // need to check for conflicting earlier writeback
- WriteQueueEntry *conflict_mshr =
- writeBuffer.findPending(miss_mshr->blkAddr,
- miss_mshr->isSecure);
- if (conflict_mshr) {
- // not sure why we don't check order here... it was in the
- // original code but commented out.
-
- // The only way this happens is if we are
- // doing a write and we didn't have permissions
- // then subsequently saw a writeback (owned got evicted)
- // We need to make sure to perform the writeback first
- // To preserve the dirty data, then we can issue the write
-
- // should we return wq_entry here instead? I.e. do we
- // have to flush writes in order? I don't think so... not
- // for Alpha anyway. Maybe for x86?
- return conflict_mshr;
-
- // @todo Note that we ignore the ready time of the conflict here
- }
-
- // No conflicts; issue read
- return miss_mshr;
- }
-
- // fall through... no pending requests. Try a prefetch.
- assert(!miss_mshr && !wq_entry);
- if (prefetcher && mshrQueue.canPrefetch()) {
- // If we have a miss queue slot, we can try a prefetch
- PacketPtr pkt = prefetcher->getPacket();
- if (pkt) {
- Addr pf_addr = pkt->getBlockAddr(blkSize);
- if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
- !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
- !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
- // Update statistic on number of prefetches issued
- // (hwpf_mshr_misses)
- assert(pkt->req->masterId() < system->maxMasters());
- mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
-
- // allocate an MSHR and return it, note
- // that we send the packet straight away, so do not
- // schedule the send
- return allocateMissBuffer(pkt, curTick(), false);
- } else {
- // free the request and packet
- delete pkt->req;
- delete pkt;
- }
- }
- }
-
- return nullptr;
-}
-
bool
-Cache::isCachedAbove(PacketPtr pkt, bool is_timing) const
+Cache::isCachedAbove(PacketPtr pkt, bool is_timing)
{
if (!forwardSnoops)
return false;
// generate a snoop response.
assert(pkt->isEviction() || pkt->cmd == MemCmd::WriteClean);
snoop_pkt.senderState = nullptr;
- cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
+ cpuSidePort.sendTimingSnoopReq(&snoop_pkt);
// Writeback/CleanEvict snoops do not generate a snoop response.
assert(!(snoop_pkt.cacheResponding()));
return snoop_pkt.isBlockCached();
} else {
- cpuSidePort->sendAtomicSnoop(pkt);
+ cpuSidePort.sendAtomicSnoop(pkt);
return pkt->isBlockCached();
}
}
-Tick
-Cache::nextQueueReadyTime() const
-{
- Tick nextReady = std::min(mshrQueue.nextReadyTime(),
- writeBuffer.nextReadyTime());
-
- // Don't signal prefetch ready time if no MSHRs available
- // Will signal once enoguh MSHRs are deallocated
- if (prefetcher && mshrQueue.canPrefetch()) {
- nextReady = std::min(nextReady,
- prefetcher->nextPrefetchReadyTime());
- }
-
- return nextReady;
-}
-
bool
Cache::sendMSHRQueuePacket(MSHR* mshr)
{
// use request from 1st target
PacketPtr tgt_pkt = mshr->getTarget()->pkt;
- DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print());
-
- CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
-
if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) {
+ DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print());
+
// we should never have hardware prefetches to allocated
// blocks
- assert(blk == nullptr);
+ assert(!tags->findBlock(mshr->blkAddr, mshr->isSecure));
// We need to check the caches above us to verify that
// they don't have a copy of this block in the dirty state
// normal response, hence it needs the MSHR as its sender
// state
snoop_pkt.senderState = mshr;
- cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
+ cpuSidePort.sendTimingSnoopReq(&snoop_pkt);
// Check to see if the prefetch was squashed by an upper cache (to
// prevent us from grabbing the line) or if a Check to see if a
// prefetchSquash first may result in the MSHR being
// prematurely deallocated.
if (snoop_pkt.cacheResponding()) {
- auto M5_VAR_USED r = outstandingSnoop.insert(snoop_pkt.req);
+ M5_VAR_USED auto r = outstandingSnoop.insert(snoop_pkt.req);
assert(r.second);
// if we are getting a snoop response with no sharers it
}
// given that no response is expected, delete Request and Packet
- delete tgt_pkt->req;
delete tgt_pkt;
return false;
}
}
- // either a prefetch that is not present upstream, or a normal
- // MSHR request, proceed to get the packet to send downstream
- PacketPtr pkt = createMissPacket(tgt_pkt, blk, mshr->needsWritable());
-
- mshr->isForward = (pkt == nullptr);
-
- if (mshr->isForward) {
- // not a cache block request, but a response is expected
- // make copy of current packet to forward, keep current
- // copy for response handling
- pkt = new Packet(tgt_pkt, false, true);
- assert(!pkt->isWrite());
- }
-
- // play it safe and append (rather than set) the sender state,
- // as forwarded packets may already have existing state
- pkt->pushSenderState(mshr);
-
- if (pkt->isClean() && blk && blk->isDirty()) {
- // A cache clean opearation is looking for a dirty block. Mark
- // the packet so that the destination xbar can determine that
- // there will be a follow-up write packet as well.
- pkt->setSatisfied();
- }
-
- if (!memSidePort->sendTimingReq(pkt)) {
- // we are awaiting a retry, but we
- // delete the packet and will be creating a new packet
- // when we get the opportunity
- delete pkt;
-
- // note that we have now masked any requestBus and
- // schedSendEvent (we will wait for a retry before
- // doing anything), and this is so even if we do not
- // care about this packet and might override it before
- // it gets retried
- return true;
- } else {
- // As part of the call to sendTimingReq the packet is
- // forwarded to all neighbouring caches (and any caches
- // above them) as a snoop. Thus at this point we know if
- // any of the neighbouring caches are responding, and if
- // so, we know it is dirty, and we can determine if it is
- // being passed as Modified, making our MSHR the ordering
- // point
- bool pending_modified_resp = !pkt->hasSharers() &&
- pkt->cacheResponding();
- markInService(mshr, pending_modified_resp);
- if (pkt->isClean() && blk && blk->isDirty()) {
- // A cache clean opearation is looking for a dirty
- // block. If a dirty block is encountered a WriteClean
- // will update any copies to the path to the memory
- // until the point of reference.
- DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
- __func__, pkt->print(), blk->print());
- PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(),
- pkt->id);
- PacketList writebacks;
- writebacks.push_back(wb_pkt);
- doWritebacks(writebacks, 0);
- }
-
- return false;
- }
-}
-
-bool
-Cache::sendWriteQueuePacket(WriteQueueEntry* wq_entry)
-{
- assert(wq_entry);
-
- // always a single target for write queue entries
- PacketPtr tgt_pkt = wq_entry->getTarget()->pkt;
-
- DPRINTF(Cache, "%s: write %s\n", __func__, tgt_pkt->print());
-
- // forward as is, both for evictions and uncacheable writes
- if (!memSidePort->sendTimingReq(tgt_pkt)) {
- // note that we have now masked any requestBus and
- // schedSendEvent (we will wait for a retry before
- // doing anything), and this is so even if we do not
- // care about this packet and might override it before
- // it gets retried
- return true;
- } else {
- markInService(wq_entry);
- return false;
- }
-}
-
-void
-Cache::serialize(CheckpointOut &cp) const
-{
- bool dirty(isDirty());
-
- if (dirty) {
- warn("*** The cache still contains dirty data. ***\n");
- warn(" Make sure to drain the system using the correct flags.\n");
- warn(" This checkpoint will not restore correctly and dirty data "
- " in the cache will be lost!\n");
- }
-
- // Since we don't checkpoint the data in the cache, any dirty data
- // will be lost when restoring from a checkpoint of a system that
- // wasn't drained properly. Flag the checkpoint as invalid if the
- // cache contains dirty data.
- bool bad_checkpoint(dirty);
- SERIALIZE_SCALAR(bad_checkpoint);
-}
-
-void
-Cache::unserialize(CheckpointIn &cp)
-{
- bool bad_checkpoint;
- UNSERIALIZE_SCALAR(bad_checkpoint);
- if (bad_checkpoint) {
- fatal("Restoring from checkpoints with dirty caches is not supported "
- "in the classic memory system. Please remove any caches or "
- " drain them properly before taking checkpoints.\n");
- }
-}
-
-///////////////
-//
-// CpuSidePort
-//
-///////////////
-
-AddrRangeList
-Cache::CpuSidePort::getAddrRanges() const
-{
- return cache->getAddrRanges();
-}
-
-bool
-Cache::CpuSidePort::tryTiming(PacketPtr pkt)
-{
- assert(!cache->system->bypassCaches());
-
- // always let express snoop packets through if even if blocked
- if (pkt->isExpressSnoop()) {
- return true;
- } else if (isBlocked() || mustSendRetry) {
- // either already committed to send a retry, or blocked
- mustSendRetry = true;
- return false;
- }
- mustSendRetry = false;
- return true;
-}
-
-bool
-Cache::CpuSidePort::recvTimingReq(PacketPtr pkt)
-{
- assert(!cache->system->bypassCaches());
-
- // always let express snoop packets through if even if blocked
- if (pkt->isExpressSnoop() || tryTiming(pkt)) {
- cache->recvTimingReq(pkt);
- return true;
- }
- return false;
-}
-
-Tick
-Cache::CpuSidePort::recvAtomic(PacketPtr pkt)
-{
- return cache->recvAtomic(pkt);
-}
-
-void
-Cache::CpuSidePort::recvFunctional(PacketPtr pkt)
-{
- // functional request
- cache->functionalAccess(pkt, true);
-}
-
-Cache::
-CpuSidePort::CpuSidePort(const std::string &_name, Cache *_cache,
- const std::string &_label)
- : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
-{
-}
-
-Cache*
-CacheParams::create()
-{
- assert(tags);
- assert(replacement_policy);
-
- return new Cache(this);
-}
-///////////////
-//
-// MemSidePort
-//
-///////////////
-
-bool
-Cache::MemSidePort::recvTimingResp(PacketPtr pkt)
-{
- cache->recvTimingResp(pkt);
- return true;
-}
-
-// Express snooping requests to memside port
-void
-Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
-{
- // handle snooping requests
- cache->recvTimingSnoopReq(pkt);
-}
-
-Tick
-Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
-{
- return cache->recvAtomicSnoop(pkt);
-}
-
-void
-Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
-{
- // functional snoop (note that in contrast to atomic we don't have
- // a specific functionalSnoop method, as they have the same
- // behaviour regardless)
- cache->functionalAccess(pkt, false);
-}
-
-void
-Cache::CacheReqPacketQueue::sendDeferredPacket()
-{
- // sanity check
- assert(!waitingOnRetry);
-
- // there should never be any deferred request packets in the
- // queue, instead we resly on the cache to provide the packets
- // from the MSHR queue or write queue
- assert(deferredPacketReadyTime() == MaxTick);
-
- // check for request packets (requests & writebacks)
- QueueEntry* entry = cache.getNextQueueEntry();
-
- if (!entry) {
- // can happen if e.g. we attempt a writeback and fail, but
- // before the retry, the writeback is eliminated because
- // we snoop another cache's ReadEx.
- } else {
- // let our snoop responses go first if there are responses to
- // the same addresses
- if (checkConflictingSnoop(entry->blkAddr)) {
- return;
- }
- waitingOnRetry = entry->sendPacket(cache);
- }
-
- // if we succeeded and are not waiting for a retry, schedule the
- // next send considering when the next queue is ready, note that
- // snoop responses have their own packet queue and thus schedule
- // their own events
- if (!waitingOnRetry) {
- schedSendEvent(cache.nextQueueReadyTime());
- }
-}
-
-Cache::
-MemSidePort::MemSidePort(const std::string &_name, Cache *_cache,
- const std::string &_label)
- : BaseCache::CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
- _reqQueue(*_cache, *this, _snoopRespQueue, _label),
- _snoopRespQueue(*_cache, *this, _label), cache(_cache)
-{
+ return BaseCache::sendMSHRQueuePacket(mshr);
}
projects / gem5.git / blobdiff