summaryrefslogtreecommitdiff
path: root/src/mem/cache/mshr.cc
diff options
context:
space:
mode:
Diffstat (limited to 'src/mem/cache/mshr.cc')
-rw-r--r--src/mem/cache/mshr.cc424
1 files changed, 424 insertions, 0 deletions
diff --git a/src/mem/cache/mshr.cc b/src/mem/cache/mshr.cc
new file mode 100644
index 000000000..6537f6343
--- /dev/null
+++ b/src/mem/cache/mshr.cc
@@ -0,0 +1,424 @@
+/*
+ * Copyright (c) 2002-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * 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
+ */
+
+/**
+ * @file
+ * Miss Status and Handling Register (MSHR) definitions.
+ */
+
+#include <assert.h>
+#include <string>
+#include <vector>
+#include <algorithm>
+
+#include "mem/cache/mshr.hh"
+#include "sim/core.hh" // for curTick
+#include "sim/host.hh"
+#include "base/misc.hh"
+#include "mem/cache/cache.hh"
+
+using namespace std;
+
+MSHR::MSHR()
+{
+ inService = false;
+ ntargets = 0;
+ threadNum = -1;
+ targets = new TargetList();
+ deferredTargets = new TargetList();
+}
+
+
+MSHR::TargetList::TargetList()
+ : needsExclusive(false), hasUpgrade(false)
+{}
+
+
+inline void
+MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
+ Counter order, bool cpuSide, bool markPending)
+{
+ if (cpuSide) {
+ if (pkt->needsExclusive()) {
+ needsExclusive = true;
+ }
+
+ if (pkt->cmd == MemCmd::UpgradeReq) {
+ hasUpgrade = true;
+ }
+ }
+
+ if (markPending) {
+ MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
+ if (mshr != NULL) {
+ assert(!mshr->downstreamPending);
+ mshr->downstreamPending = true;
+ }
+ }
+
+ push_back(Target(pkt, readyTime, order, cpuSide, markPending));
+}
+
+
+void
+MSHR::TargetList::replaceUpgrades()
+{
+ if (!hasUpgrade)
+ return;
+
+ Iterator end_i = end();
+ for (Iterator i = begin(); i != end_i; ++i) {
+ if (i->pkt->cmd == MemCmd::UpgradeReq) {
+ i->pkt->cmd = MemCmd::ReadExReq;
+ DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
+ }
+ }
+
+ hasUpgrade = false;
+}
+
+
+void
+MSHR::TargetList::clearDownstreamPending()
+{
+ Iterator end_i = end();
+ for (Iterator i = begin(); i != end_i; ++i) {
+ if (i->markedPending) {
+ MSHR *mshr = dynamic_cast<MSHR*>(i->pkt->senderState);
+ if (mshr != NULL) {
+ mshr->clearDownstreamPending();
+ }
+ }
+ }
+}
+
+
+bool
+MSHR::TargetList::checkFunctional(PacketPtr pkt)
+{
+ Iterator end_i = end();
+ for (Iterator i = begin(); i != end_i; ++i) {
+ if (pkt->checkFunctional(i->pkt)) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+
+void
+MSHR::TargetList::
+print(std::ostream &os, int verbosity, const std::string &prefix) const
+{
+ ConstIterator end_i = end();
+ for (ConstIterator i = begin(); i != end_i; ++i) {
+ ccprintf(os, "%s%s: ", prefix, i->isCpuSide() ? "cpu" : "mem");
+ i->pkt->print(os, verbosity, "");
+ }
+}
+
+
+void
+MSHR::allocate(Addr _addr, int _size, PacketPtr target,
+ Tick whenReady, Counter _order)
+{
+ addr = _addr;
+ size = _size;
+ readyTime = whenReady;
+ order = _order;
+ assert(target);
+ isCacheFill = false;
+ _isUncacheable = target->req->isUncacheable();
+ inService = false;
+ downstreamPending = false;
+ threadNum = 0;
+ ntargets = 1;
+ // Don't know of a case where we would allocate a new MSHR for a
+ // snoop (mem-side request), so set cpuSide to true here.
+ assert(targets->isReset());
+ targets->add(target, whenReady, _order, true, true);
+ assert(deferredTargets->isReset());
+ pendingInvalidate = false;
+ pendingShared = false;
+ data = NULL;
+}
+
+
+void
+MSHR::clearDownstreamPending()
+{
+ assert(downstreamPending);
+ downstreamPending = false;
+ // recursively clear flag on any MSHRs we will be forwarding
+ // responses to
+ targets->clearDownstreamPending();
+}
+
+bool
+MSHR::markInService()
+{
+ assert(!inService);
+ if (isSimpleForward()) {
+ // we just forwarded the request packet & don't expect a
+ // response, so get rid of it
+ assert(getNumTargets() == 1);
+ popTarget();
+ return true;
+ }
+ inService = true;
+ if (!downstreamPending) {
+ // let upstream caches know that the request has made it to a
+ // level where it's going to get a response
+ targets->clearDownstreamPending();
+ }
+ return false;
+}
+
+
+void
+MSHR::deallocate()
+{
+ assert(targets->empty());
+ targets->resetFlags();
+ assert(deferredTargets->isReset());
+ assert(ntargets == 0);
+ inService = false;
+ //allocIter = NULL;
+ //readyIter = NULL;
+}
+
+/*
+ * Adds a target to an MSHR
+ */
+void
+MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
+{
+ // if there's a request already in service for this MSHR, we will
+ // have to defer the new target until after the response if any of
+ // the following are true:
+ // - there are other targets already deferred
+ // - there's a pending invalidate to be applied after the response
+ // comes back (but before this target is processed)
+ // - the outstanding request is for a non-exclusive block and this
+ // target requires an exclusive block
+ if (inService &&
+ (!deferredTargets->empty() || pendingInvalidate ||
+ (!targets->needsExclusive && pkt->needsExclusive()))) {
+ // need to put on deferred list
+ deferredTargets->add(pkt, whenReady, _order, true, true);
+ } else {
+ // No request outstanding, or still OK to append to
+ // outstanding request: append to regular target list. Only
+ // mark pending if current request hasn't been issued yet
+ // (isn't in service).
+ targets->add(pkt, whenReady, _order, true, !inService);
+ }
+
+ ++ntargets;
+}
+
+bool
+MSHR::handleSnoop(PacketPtr pkt, Counter _order)
+{
+ if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
+ // Request has not been issued yet, or it's been issued
+ // locally but is buffered unissued at some downstream cache
+ // which is forwarding us this snoop. Either way, the packet
+ // we're snooping logically precedes this MSHR's request, so
+ // the snoop has no impact on the MSHR, but must be processed
+ // in the standard way by the cache. The only exception is
+ // that if we're an L2+ cache buffering an UpgradeReq from a
+ // higher-level cache, and the snoop is invalidating, then our
+ // buffered upgrades must be converted to read exclusives,
+ // since the upper-level cache no longer has a valid copy.
+ // That is, even though the upper-level cache got out on its
+ // local bus first, some other invalidating transaction
+ // reached the global bus before the upgrade did.
+ if (pkt->needsExclusive()) {
+ targets->replaceUpgrades();
+ deferredTargets->replaceUpgrades();
+ }
+
+ return false;
+ }
+
+ // From here on down, the request issued by this MSHR logically
+ // precedes the request we're snooping.
+
+ if (pkt->needsExclusive()) {
+ // snooped request still precedes the re-request we'll have to
+ // issue for deferred targets, if any...
+ deferredTargets->replaceUpgrades();
+ }
+
+ if (pendingInvalidate) {
+ // a prior snoop has already appended an invalidation, so
+ // logically we don't have the block anymore; no need for
+ // further snooping.
+ return true;
+ }
+
+ if (targets->needsExclusive || pkt->needsExclusive()) {
+ // actual target device (typ. PhysicalMemory) will delete the
+ // packet on reception, so we need to save a copy here
+ PacketPtr cp_pkt = new Packet(pkt, true);
+ targets->add(cp_pkt, curTick, _order, false,
+ downstreamPending && targets->needsExclusive);
+ ++ntargets;
+
+ if (targets->needsExclusive) {
+ // We're awaiting an exclusive copy, so ownership is pending.
+ // It's up to us to respond once the data arrives.
+ pkt->assertMemInhibit();
+ pkt->setSupplyExclusive();
+ } else {
+ // Someone else may respond before we get around to
+ // processing this snoop, which means the copied request
+ // pointer will no longer be valid
+ cp_pkt->req = NULL;
+ }
+
+ if (pkt->needsExclusive()) {
+ // This transaction will take away our pending copy
+ pendingInvalidate = true;
+ }
+ } else {
+ // Read to a read: no conflict, so no need to record as
+ // target, but make sure neither reader thinks he's getting an
+ // exclusive copy
+ pendingShared = true;
+ pkt->assertShared();
+ }
+
+ return true;
+}
+
+
+bool
+MSHR::promoteDeferredTargets()
+{
+ assert(targets->empty());
+ if (deferredTargets->empty()) {
+ return false;
+ }
+
+ // swap targets & deferredTargets lists
+ TargetList *tmp = targets;
+ targets = deferredTargets;
+ deferredTargets = tmp;
+
+ assert(targets->size() == ntargets);
+
+ // clear deferredTargets flags
+ deferredTargets->resetFlags();
+
+ pendingInvalidate = false;
+ pendingShared = false;
+ order = targets->front().order;
+ readyTime = std::max(curTick, targets->front().readyTime);
+
+ return true;
+}
+
+
+void
+MSHR::handleFill(Packet *pkt, CacheBlk *blk)
+{
+ if (pendingShared) {
+ // we snooped another read while this read was in
+ // service... assert shared line on its behalf
+ pkt->assertShared();
+ }
+
+ if (!pkt->sharedAsserted() && !pendingInvalidate
+ && deferredTargets->needsExclusive) {
+ // We got an exclusive response, but we have deferred targets
+ // which are waiting to request an exclusive copy (not because
+ // of a pending invalidate). This can happen if the original
+ // request was for a read-only (non-exclusive) block, but we
+ // got an exclusive copy anyway because of the E part of the
+ // MOESI/MESI protocol. Since we got the exclusive copy
+ // there's no need to defer the targets, so move them up to
+ // the regular target list.
+ assert(!targets->needsExclusive);
+ targets->needsExclusive = true;
+ // if any of the deferred targets were upper-level cache
+ // requests marked downstreamPending, need to clear that
+ assert(!downstreamPending); // not pending here anymore
+ deferredTargets->clearDownstreamPending();
+ // this clears out deferredTargets too
+ targets->splice(targets->end(), *deferredTargets);
+ deferredTargets->resetFlags();
+ }
+}
+
+
+bool
+MSHR::checkFunctional(PacketPtr pkt)
+{
+ // For printing, we treat the MSHR as a whole as single entity.
+ // For other requests, we iterate over the individual targets
+ // since that's where the actual data lies.
+ if (pkt->isPrint()) {
+ pkt->checkFunctional(this, addr, size, NULL);
+ return false;
+ } else {
+ return (targets->checkFunctional(pkt) ||
+ deferredTargets->checkFunctional(pkt));
+ }
+}
+
+
+void
+MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
+{
+ ccprintf(os, "%s[%x:%x] %s %s %s state: %s %s %s %s\n",
+ prefix, addr, addr+size-1,
+ isCacheFill ? "Fill" : "",
+ needsExclusive() ? "Excl" : "",
+ _isUncacheable ? "Unc" : "",
+ inService ? "InSvc" : "",
+ downstreamPending ? "DwnPend" : "",
+ pendingInvalidate ? "PendInv" : "",
+ pendingShared ? "PendShared" : "");
+
+ ccprintf(os, "%s Targets:\n", prefix);
+ targets->print(os, verbosity, prefix + " ");
+ if (!deferredTargets->empty()) {
+ ccprintf(os, "%s Deferred Targets:\n", prefix);
+ deferredTargets->print(os, verbosity, prefix + " ");
+ }
+}
+
+MSHR::~MSHR()
+{
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 02:39:55 +0000