/*
- * Copyright (c) 2013-2016 ARM Limited
+ * Copyright (c) 2013-2017,2019 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: Stephan Diestelhorst
*/
/**
* Implementation of a snoop filter.
*/
-#include "base/misc.hh"
+#include "mem/snoop_filter.hh"
+
+#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/SnoopFilter.hh"
-#include "mem/snoop_filter.hh"
#include "sim/system.hh"
+const int SnoopFilter::SNOOP_MASK_SIZE;
+
void
SnoopFilter::eraseIfNullEntry(SnoopFilterCache::iterator& sf_it)
{
SnoopItem& sf_item = sf_it->second;
- if (!(sf_item.requested | sf_item.holder)) {
+ if ((sf_item.requested | sf_item.holder).none()) {
cachedLocations.erase(sf_it);
DPRINTF(SnoopFilter, "%s: Removed SF entry.\n",
__func__);
}
std::pair<SnoopFilter::SnoopList, Cycles>
-SnoopFilter::lookupRequest(const Packet* cpkt, const SlavePort& slave_port)
+SnoopFilter::lookupRequest(const Packet* cpkt, const ResponsePort&
+ cpu_side_port)
{
DPRINTF(SnoopFilter, "%s: src %s packet %s\n", __func__,
- slave_port.name(), cpkt->print());
+ cpu_side_port.name(), cpkt->print());
// check if the packet came from a cache
- bool allocate = !cpkt->req->isUncacheable() && slave_port.isSnooping() &&
- cpkt->fromCache();
+ bool allocate = !cpkt->req->isUncacheable() && cpu_side_port.isSnooping()
+ && cpkt->fromCache();
Addr line_addr = cpkt->getBlockAddr(linesize);
if (cpkt->isSecure()) {
line_addr |= LineSecure;
}
- SnoopMask req_port = portToMask(slave_port);
- reqLookupResult = cachedLocations.find(line_addr);
- bool is_hit = (reqLookupResult != cachedLocations.end());
+ SnoopMask req_port = portToMask(cpu_side_port);
+ reqLookupResult.it = cachedLocations.find(line_addr);
+ bool is_hit = (reqLookupResult.it != cachedLocations.end());
// If the snoop filter has no entry, and we should not allocate,
// do not create a new snoop filter entry, simply return a NULL
return snoopDown(lookupLatency);
// If no hit in snoop filter create a new element and update iterator
- if (!is_hit)
- reqLookupResult = cachedLocations.emplace(line_addr, SnoopItem()).first;
- SnoopItem& sf_item = reqLookupResult->second;
+ if (!is_hit) {
+ reqLookupResult.it =
+ cachedLocations.emplace(line_addr, SnoopItem()).first;
+ }
+ SnoopItem& sf_item = reqLookupResult.it->second;
SnoopMask interested = sf_item.holder | sf_item.requested;
// Store unmodified value of snoop filter item in temp storage in
// case we need to revert because of a send retry in
// updateRequest.
- retryItem = sf_item;
+ reqLookupResult.retryItem = sf_item;
totRequests++;
if (is_hit) {
- // Single bit set -> value is a power of two
- if (isPow2(interested))
+ if (interested.count() == 1)
hitSingleRequests++;
else
hitMultiRequests++;
if (cpkt->needsResponse()) {
if (!cpkt->cacheResponding()) {
// Max one request per address per port
- panic_if(sf_item.requested & req_port, "double request :( " \
- "SF value %x.%x\n", sf_item.requested, sf_item.holder);
+ panic_if((sf_item.requested & req_port).any(),
+ "double request :( SF value %x.%x\n",
+ sf_item.requested, sf_item.holder);
// Mark in-flight requests to distinguish later on
sf_item.requested |= req_port;
// to the CPU, already -> the response will not be seen by this
// filter -> we do not need to keep the in-flight request, but make
// sure that we know that that cluster has a copy
- panic_if(!(sf_item.holder & req_port), "Need to hold the value!");
+ panic_if((sf_item.holder & req_port).none(),
+ "Need to hold the value!");
DPRINTF(SnoopFilter,
"%s: not marking request. SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
} else { // if (!cpkt->needsResponse())
assert(cpkt->isEviction());
// make sure that the sender actually had the line
- panic_if(!(sf_item.holder & req_port), "requester %x is not a " \
+ panic_if((sf_item.holder & req_port).none(), "requestor %x is not a " \
"holder :( SF value %x.%x\n", req_port,
sf_item.requested, sf_item.holder);
// CleanEvicts and Writebacks -> the sender and all caches above
void
SnoopFilter::finishRequest(bool will_retry, Addr addr, bool is_secure)
{
- if (reqLookupResult != cachedLocations.end()) {
+ if (reqLookupResult.it != cachedLocations.end()) {
// since we rely on the caller, do a basic check to ensure
// that finishRequest is being called following lookupRequest
Addr line_addr = (addr & ~(Addr(linesize - 1)));
if (is_secure) {
line_addr |= LineSecure;
}
- assert(reqLookupResult->first == line_addr);
+ assert(reqLookupResult.it->first == line_addr);
if (will_retry) {
+ SnoopItem retry_item = reqLookupResult.retryItem;
// Undo any changes made in lookupRequest to the snoop filter
// entry if the request will come again. retryItem holds
// the previous value of the snoopfilter entry.
- reqLookupResult->second = retryItem;
+ reqLookupResult.it->second = retry_item;
DPRINTF(SnoopFilter, "%s: restored SF value %x.%x\n",
- __func__, retryItem.requested, retryItem.holder);
+ __func__, retry_item.requested, retry_item.holder);
}
- eraseIfNullEntry(reqLookupResult);
+ eraseIfNullEntry(reqLookupResult.it);
}
}
SnoopItem& sf_item = sf_it->second;
- DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
- __func__, sf_item.requested, sf_item.holder);
-
SnoopMask interested = (sf_item.holder | sf_item.requested);
totSnoops++;
- // Single bit set -> value is a power of two
- if (isPow2(interested))
+
+ if (interested.count() == 1)
hitSingleSnoops++;
else
hitMultiSnoops++;
// ReadEx and Writes require both invalidation and exlusivity, while reads
// require neither. Writebacks on the other hand require exclusivity but
// not the invalidation. Previously Writebacks did not generate upward
- // snoops so this was never an aissue. Now that Writebacks generate snoops
- // we need to special case for Writebacks.
+ // snoops so this was never an issue. Now that Writebacks generate snoops
+ // we need a special case for Writebacks. Additionally cache maintenance
+ // operations can generate snoops as they clean and/or invalidate all
+ // caches down to the specified point of reference.
assert(cpkt->isWriteback() || cpkt->req->isUncacheable() ||
- (cpkt->isInvalidate() == cpkt->needsWritable()));
- if (cpkt->isInvalidate() && !sf_item.requested) {
+ (cpkt->isInvalidate() == cpkt->needsWritable()) ||
+ cpkt->req->isCacheMaintenance());
+ if (cpkt->isInvalidate() && sf_item.requested.none()) {
// Early clear of the holder, if no other request is currently going on
// @todo: This should possibly be updated even though we do not filter
// upward snoops
+ DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
+ __func__, sf_item.requested, sf_item.holder);
sf_item.holder = 0;
+ DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
+ __func__, sf_item.requested, sf_item.holder);
+ eraseIfNullEntry(sf_it);
}
- eraseIfNullEntry(sf_it);
- DPRINTF(SnoopFilter, "%s: new SF value %x.%x interest: %x \n",
- __func__, sf_item.requested, sf_item.holder, interested);
-
return snoopSelected(maskToPortList(interested), lookupLatency);
}
void
SnoopFilter::updateSnoopResponse(const Packet* cpkt,
- const SlavePort& rsp_port,
- const SlavePort& req_port)
+ const ResponsePort& rsp_port,
+ const ResponsePort& req_port)
{
DPRINTF(SnoopFilter, "%s: rsp %s req %s packet %s\n",
__func__, rsp_port.name(), req_port.name(), cpkt->print());
__func__, sf_item.requested, sf_item.holder);
// The source should have the line
- panic_if(!(sf_item.holder & rsp_mask), "SF value %x.%x does not have "\
- "the line\n", sf_item.requested, sf_item.holder);
+ panic_if((sf_item.holder & rsp_mask).none(),
+ "SF value %x.%x does not have the line\n",
+ sf_item.requested, sf_item.holder);
// The destination should have had a request in
- panic_if(!(sf_item.requested & req_mask), "SF value %x.%x missing "\
+ panic_if((sf_item.requested & req_mask).none(), "SF value %x.%x missing "\
"the original request\n", sf_item.requested, sf_item.holder);
// If the snoop response has no sharers the line is passed in
// @todo Deal with invalidating responses
sf_item.holder |= req_mask;
sf_item.requested &= ~req_mask;
- assert(sf_item.requested | sf_item.holder);
+ assert((sf_item.requested | sf_item.holder).any());
DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
}
void
SnoopFilter::updateSnoopForward(const Packet* cpkt,
- const SlavePort& rsp_port, const MasterPort& req_port)
+ const ResponsePort& rsp_port, const RequestPort& req_port)
{
DPRINTF(SnoopFilter, "%s: rsp %s req %s packet %s\n",
__func__, rsp_port.name(), req_port.name(), cpkt->print());
if (!is_hit)
return;
- SnoopItem& sf_item = sf_it->second;
-
- DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
- __func__, sf_item.requested, sf_item.holder);
-
// If the snoop response has no sharers the line is passed in
// Modified state, and we know that there are no other copies, or
// they will all be invalidated imminently
if (!cpkt->hasSharers()) {
+ SnoopItem& sf_item = sf_it->second;
+
+ DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
+ __func__, sf_item.requested, sf_item.holder);
sf_item.holder = 0;
- }
- DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
- __func__, sf_item.requested, sf_item.holder);
- eraseIfNullEntry(sf_it);
+ DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
+ __func__, sf_item.requested, sf_item.holder);
+ eraseIfNullEntry(sf_it);
+ }
}
void
-SnoopFilter::updateResponse(const Packet* cpkt, const SlavePort& slave_port)
+SnoopFilter::updateResponse(const Packet* cpkt, const ResponsePort&
+ cpu_side_port)
{
DPRINTF(SnoopFilter, "%s: src %s packet %s\n",
- __func__, slave_port.name(), cpkt->print());
+ __func__, cpu_side_port.name(), cpkt->print());
assert(cpkt->isResponse());
// we only allocate if the packet actually came from a cache, but
// start by checking if the port is snooping
- if (cpkt->req->isUncacheable() || !slave_port.isSnooping())
+ if (cpkt->req->isUncacheable() || !cpu_side_port.isSnooping())
return;
// next check if we actually allocated an entry
if (sf_it == cachedLocations.end())
return;
- SnoopMask slave_mask = portToMask(slave_port);
+ SnoopMask response_mask = portToMask(cpu_side_port);
SnoopItem& sf_item = sf_it->second;
DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
// Make sure we have seen the actual request, too
- panic_if(!(sf_item.requested & slave_mask), "SF value %x.%x missing "\
- "request bit\n", sf_item.requested, sf_item.holder);
-
- // Update the residency of the cache line. If the response has no
- // sharers we know that the line has been invalidated in all
- // branches that are not where we are responding to.
- if (!cpkt->hasSharers())
- sf_item.holder = 0;
- sf_item.holder |= slave_mask;
- sf_item.requested &= ~slave_mask;
- assert(sf_item.holder | sf_item.requested);
+ panic_if((sf_item.requested & response_mask).none(),
+ "SF value %x.%x missing request bit\n",
+ sf_item.requested, sf_item.holder);
+
+ sf_item.requested &= ~response_mask;
+ // Update the residency of the cache line.
+
+ if (cpkt->req->isCacheMaintenance()) {
+ // A cache clean response does not carry any data so it
+ // shouldn't change the holders, unless it is invalidating.
+ if (cpkt->isInvalidate()) {
+ sf_item.holder &= ~response_mask;
+ }
+ eraseIfNullEntry(sf_it);
+ } else {
+ // Any other response implies that a cache above will have the
+ // block.
+ sf_item.holder |= response_mask;
+ assert((sf_item.holder | sf_item.requested).any());
+ }
DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
}
.desc("Number of snoops hitting in the snoop filter with multiple "\
"(>1) holders of the requested data.");
}
-
-SnoopFilter *
-SnoopFilterParams::create()
-{
- return new SnoopFilter(this);
-}
projects / gem5.git / blobdiff