/*
- * Copyright (c) 2011-2014 ARM Limited
+ * Copyright (c) 2011-2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* Definition of a crossbar object.
*/
-#include "base/misc.hh"
+#include "mem/xbar.hh"
+
+#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/AddrRanges.hh"
#include "debug/Drain.hh"
#include "debug/XBar.hh"
-#include "mem/xbar.hh"
BaseXBar::BaseXBar(const BaseXBarParams *p)
: MemObject(p),
- headerCycles(p->header_cycles), width(p->width),
+ frontendLatency(p->frontend_latency),
+ forwardLatency(p->forward_latency),
+ responseLatency(p->response_latency),
+ width(p->width),
gotAddrRanges(p->port_default_connection_count +
p->port_master_connection_count, false),
gotAllAddrRanges(false), defaultPortID(InvalidPortID),
}
void
-BaseXBar::calcPacketTiming(PacketPtr pkt)
+BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay)
{
// the crossbar will be called at a time that is not necessarily
// coinciding with its own clock, so start by determining how long
// until the next clock edge (could be zero)
Tick offset = clockEdge() - curTick();
- // Determine how many cycles are needed to send the data
- // If the packet has no data we take into account just the cycle to send
- // the header.
- unsigned dataCycles = pkt->hasData() ? divCeil(pkt->getSize(), width) : 0;
-
- // before setting the bus delay fields of the packet, ensure that
- // the delay from any previous crossbar has been accounted for
- if (pkt->headerDelay != 0 || pkt->payloadDelay != 0)
- panic("Packet %s already has delay (%d, %d) that should be "
- "accounted for.\n", pkt->cmdString(), pkt->headerDelay,
- pkt->payloadDelay);
-
- // The headerDelay takes into account the relative time to deliver the
- // header of the packet. It will be charged of the additional delay of
- // the xbar if the packet goes through it.
- pkt->headerDelay = (headerCycles + 1) * clockPeriod() + offset;
-
- // The payloadDelay takes into account the relative time to deliver the
- // payload of the packet. If the packet has no data its value is just one
- // tick (due to header) plus the offset value.
- pkt->payloadDelay = (headerCycles + dataCycles) * clockPeriod() + offset;
+ // the header delay depends on the path through the crossbar, and
+ // we therefore rely on the caller to provide the actual
+ // value
+ pkt->headerDelay += offset + header_delay;
+
+ // note that we add the header delay to the existing value, and
+ // align it to the crossbar clock
+
+ // do a quick sanity check to ensure the timings are not being
+ // ignored, note that this specific value may cause problems for
+ // slower interconnects
+ panic_if(pkt->headerDelay > SimClock::Int::us,
+ "Encountered header delay exceeding 1 us\n");
+
+ if (pkt->hasData()) {
+ // the payloadDelay takes into account the relative time to
+ // deliver the payload of the packet, after the header delay,
+ // we take the maximum since the payload delay could already
+ // be longer than what this parcitular crossbar enforces.
+ pkt->payloadDelay = std::max<Tick>(pkt->payloadDelay,
+ divCeil(pkt->getSize(), width) *
+ clockPeriod());
+ }
+
+ // the payload delay is not paying for the clock offset as that is
+ // already done using the header delay, and the payload delay is
+ // also used to determine how long the crossbar layer is busy and
+ // thus regulates throughput
}
template <typename SrcType, typename DstType>
BaseXBar::Layer<SrcType,DstType>::Layer(DstType& _port, BaseXBar& _xbar,
const std::string& _name) :
- port(_port), xbar(_xbar), _name(_name), state(IDLE), drainManager(NULL),
- waitingForPeer(NULL), releaseEvent(this)
+ port(_port), xbar(_xbar), _name(_name), state(IDLE),
+ waitingForPeer(NULL), releaseEvent([this]{ releaseLayer(); }, name())
{
}
// waiting for the peer
if (waitingForPeer == NULL)
retryWaiting();
- } else if (waitingForPeer == NULL && drainManager) {
+ } else if (waitingForPeer == NULL && drainState() == DrainState::Draining) {
DPRINTF(Drain, "Crossbar done draining, signaling drain manager\n");
//If we weren't able to drain before, do it now.
- drainManager->signalDrainDone();
- // Clear the drain event once we're done with it.
- drainManager = NULL;
+ signalDrainDone();
}
}
// tell the port to retry, which in some cases ends up calling the
// layer again
- retryingPort->sendRetry();
+ sendRetry(retryingPort);
// If the layer is still in the retry state, sendTiming wasn't
- // called in zero time (e.g. the cache does this), burn a cycle
+ // called in zero time (e.g. the cache does this when a writeback
+ // is squashed)
if (state == RETRY) {
// update the state to busy and reset the retrying port, we
// have done our bit and sent the retry
state = BUSY;
- // occupy the crossbar layer until the next cycle ends
- occupyLayer(xbar.clockEdge(Cycles(1)));
+ // occupy the crossbar layer until the next clock edge
+ occupyLayer(xbar.clockEdge());
}
}
void
BaseXBar::regStats()
{
+ ClockedObject::regStats();
+
using namespace Stats;
transDist
}
template <typename SrcType, typename DstType>
-unsigned int
-BaseXBar::Layer<SrcType,DstType>::drain(DrainManager *dm)
+DrainState
+BaseXBar::Layer<SrcType,DstType>::drain()
{
//We should check that we're not "doing" anything, and that noone is
//waiting. We might be idle but have someone waiting if the device we
//contacted for a retry didn't actually retry.
if (state != IDLE) {
DPRINTF(Drain, "Crossbar not drained\n");
- drainManager = dm;
- return 1;
+ return DrainState::Draining;
+ } else {
+ return DrainState::Drained;
}
- return 0;
}
template <typename SrcType, typename DstType>
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