gem5/src/mem/comm_monitor.cc
Andreas Hansson 0fcb376e5f mem: Make cache terminology easier to understand
This patch changes the name of a bunch of packet flags and MSHR member
functions and variables to make the coherency protocol easier to
understand. In addition the patch adds and updates lots of
descriptions, explicitly spelling out assumptions.

The following name changes are made:

* the packet memInhibit flag is renamed to cacheResponding

* the packet sharedAsserted flag is renamed to hasSharers

* the packet NeedsExclusive attribute is renamed to NeedsWritable

* the packet isSupplyExclusive is renamed responderHadWritable

* the MSHR pendingDirty is renamed to pendingModified

The cache states, Modified, Owned, Exclusive, Shared are also called
out in the cache and MSHR code to make it easier to understand.
2015-12-31 09:32:58 -05:00

553 lines
17 KiB
C++

/*
* Copyright (c) 2012-2013, 2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* 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: Thomas Grass
* Andreas Hansson
*/
#include "base/trace.hh"
#include "debug/CommMonitor.hh"
#include "mem/comm_monitor.hh"
#include "sim/stats.hh"
CommMonitor::CommMonitor(Params* params)
: MemObject(params),
masterPort(name() + "-master", *this),
slavePort(name() + "-slave", *this),
samplePeriodicEvent(this),
samplePeriodTicks(params->sample_period),
samplePeriod(params->sample_period / SimClock::Float::s),
readAddrMask(params->read_addr_mask),
writeAddrMask(params->write_addr_mask),
stats(params)
{
DPRINTF(CommMonitor,
"Created monitor %s with sample period %d ticks (%f ms)\n",
name(), samplePeriodTicks, samplePeriod * 1E3);
}
CommMonitor*
CommMonitorParams::create()
{
return new CommMonitor(this);
}
void
CommMonitor::init()
{
// make sure both sides of the monitor are connected
if (!slavePort.isConnected() || !masterPort.isConnected())
fatal("Communication monitor is not connected on both sides.\n");
}
void
CommMonitor::regProbePoints()
{
ppPktReq.reset(new ProbePoints::Packet(getProbeManager(), "PktRequest"));
ppPktResp.reset(new ProbePoints::Packet(getProbeManager(), "PktResponse"));
}
BaseMasterPort&
CommMonitor::getMasterPort(const std::string& if_name, PortID idx)
{
if (if_name == "master") {
return masterPort;
} else {
return MemObject::getMasterPort(if_name, idx);
}
}
BaseSlavePort&
CommMonitor::getSlavePort(const std::string& if_name, PortID idx)
{
if (if_name == "slave") {
return slavePort;
} else {
return MemObject::getSlavePort(if_name, idx);
}
}
void
CommMonitor::recvFunctional(PacketPtr pkt)
{
masterPort.sendFunctional(pkt);
}
void
CommMonitor::recvFunctionalSnoop(PacketPtr pkt)
{
slavePort.sendFunctionalSnoop(pkt);
}
Tick
CommMonitor::recvAtomic(PacketPtr pkt)
{
ProbePoints::PacketInfo req_pkt_info(pkt);
ppPktReq->notify(req_pkt_info);
const Tick delay(masterPort.sendAtomic(pkt));
assert(pkt->isResponse());
ProbePoints::PacketInfo resp_pkt_info(pkt);
ppPktResp->notify(resp_pkt_info);
return delay;
}
Tick
CommMonitor::recvAtomicSnoop(PacketPtr pkt)
{
return slavePort.sendAtomicSnoop(pkt);
}
bool
CommMonitor::recvTimingReq(PacketPtr pkt)
{
// should always see a request
assert(pkt->isRequest());
// Store relevant fields of packet, because packet may be modified
// or even deleted when sendTiming() is called.
const ProbePoints::PacketInfo pkt_info(pkt);
const bool is_read = pkt->isRead();
const bool is_write = pkt->isWrite();
const bool expects_response(
pkt->needsResponse() && !pkt->cacheResponding());
// If a cache miss is served by a cache, a monitor near the memory
// would see a request which needs a response, but this response
// would not come back from the memory. Therefore we additionally
// have to check the cacheResponding flag
if (expects_response && !stats.disableLatencyHists) {
pkt->pushSenderState(new CommMonitorSenderState(curTick()));
}
// Attempt to send the packet
bool successful = masterPort.sendTimingReq(pkt);
// If not successful, restore the sender state
if (!successful && expects_response && !stats.disableLatencyHists) {
delete pkt->popSenderState();
}
if (successful) {
ppPktReq->notify(pkt_info);
}
if (successful && is_read) {
DPRINTF(CommMonitor, "Forwarded read request\n");
// Increment number of observed read transactions
if (!stats.disableTransactionHists) {
++stats.readTrans;
}
// Get sample of burst length
if (!stats.disableBurstLengthHists) {
stats.readBurstLengthHist.sample(pkt_info.size);
}
// Sample the masked address
if (!stats.disableAddrDists) {
stats.readAddrDist.sample(pkt_info.addr & readAddrMask);
}
// If it needs a response increment number of outstanding read
// requests
if (!stats.disableOutstandingHists && expects_response) {
++stats.outstandingReadReqs;
}
if (!stats.disableITTDists) {
// Sample value of read-read inter transaction time
if (stats.timeOfLastRead != 0) {
stats.ittReadRead.sample(curTick() - stats.timeOfLastRead);
}
stats.timeOfLastRead = curTick();
// Sample value of req-req inter transaction time
if (stats.timeOfLastReq != 0) {
stats.ittReqReq.sample(curTick() - stats.timeOfLastReq);
}
stats.timeOfLastReq = curTick();
}
} else if (successful && is_write) {
DPRINTF(CommMonitor, "Forwarded write request\n");
// Same as for reads
if (!stats.disableTransactionHists) {
++stats.writeTrans;
}
if (!stats.disableBurstLengthHists) {
stats.writeBurstLengthHist.sample(pkt_info.size);
}
// Update the bandwidth stats on the request
if (!stats.disableBandwidthHists) {
stats.writtenBytes += pkt_info.size;
stats.totalWrittenBytes += pkt_info.size;
}
// Sample the masked write address
if (!stats.disableAddrDists) {
stats.writeAddrDist.sample(pkt_info.addr & writeAddrMask);
}
if (!stats.disableOutstandingHists && expects_response) {
++stats.outstandingWriteReqs;
}
if (!stats.disableITTDists) {
// Sample value of write-to-write inter transaction time
if (stats.timeOfLastWrite != 0) {
stats.ittWriteWrite.sample(curTick() - stats.timeOfLastWrite);
}
stats.timeOfLastWrite = curTick();
// Sample value of req-to-req inter transaction time
if (stats.timeOfLastReq != 0) {
stats.ittReqReq.sample(curTick() - stats.timeOfLastReq);
}
stats.timeOfLastReq = curTick();
}
} else if (successful) {
DPRINTF(CommMonitor, "Forwarded non read/write request\n");
}
return successful;
}
bool
CommMonitor::recvTimingResp(PacketPtr pkt)
{
// should always see responses
assert(pkt->isResponse());
// Store relevant fields of packet, because packet may be modified
// or even deleted when sendTiming() is called.
const ProbePoints::PacketInfo pkt_info(pkt);
bool is_read = pkt->isRead();
bool is_write = pkt->isWrite();
Tick latency = 0;
CommMonitorSenderState* received_state =
dynamic_cast<CommMonitorSenderState*>(pkt->senderState);
if (!stats.disableLatencyHists) {
// Restore initial sender state
if (received_state == NULL)
panic("Monitor got a response without monitor sender state\n");
// Restore the sate
pkt->senderState = received_state->predecessor;
}
// Attempt to send the packet
bool successful = slavePort.sendTimingResp(pkt);
if (!stats.disableLatencyHists) {
// If packet successfully send, sample value of latency,
// afterwards delete sender state, otherwise restore state
if (successful) {
latency = curTick() - received_state->transmitTime;
DPRINTF(CommMonitor, "Latency: %d\n", latency);
delete received_state;
} else {
// Don't delete anything and let the packet look like we
// did not touch it
pkt->senderState = received_state;
}
}
if (successful) {
ppPktResp->notify(pkt_info);
}
if (successful && is_read) {
// Decrement number of outstanding read requests
DPRINTF(CommMonitor, "Received read response\n");
if (!stats.disableOutstandingHists) {
assert(stats.outstandingReadReqs != 0);
--stats.outstandingReadReqs;
}
if (!stats.disableLatencyHists) {
stats.readLatencyHist.sample(latency);
}
// Update the bandwidth stats based on responses for reads
if (!stats.disableBandwidthHists) {
stats.readBytes += pkt_info.size;
stats.totalReadBytes += pkt_info.size;
}
} else if (successful && is_write) {
// Decrement number of outstanding write requests
DPRINTF(CommMonitor, "Received write response\n");
if (!stats.disableOutstandingHists) {
assert(stats.outstandingWriteReqs != 0);
--stats.outstandingWriteReqs;
}
if (!stats.disableLatencyHists) {
stats.writeLatencyHist.sample(latency);
}
} else if (successful) {
DPRINTF(CommMonitor, "Received non read/write response\n");
}
return successful;
}
void
CommMonitor::recvTimingSnoopReq(PacketPtr pkt)
{
slavePort.sendTimingSnoopReq(pkt);
}
bool
CommMonitor::recvTimingSnoopResp(PacketPtr pkt)
{
return masterPort.sendTimingSnoopResp(pkt);
}
void
CommMonitor::recvRetrySnoopResp()
{
slavePort.sendRetrySnoopResp();
}
bool
CommMonitor::isSnooping() const
{
// check if the connected master port is snooping
return slavePort.isSnooping();
}
AddrRangeList
CommMonitor::getAddrRanges() const
{
// get the address ranges of the connected slave port
return masterPort.getAddrRanges();
}
void
CommMonitor::recvReqRetry()
{
slavePort.sendRetryReq();
}
void
CommMonitor::recvRespRetry()
{
masterPort.sendRetryResp();
}
void
CommMonitor::recvRangeChange()
{
slavePort.sendRangeChange();
}
void
CommMonitor::regStats()
{
// Initialise all the monitor stats
using namespace Stats;
stats.readBurstLengthHist
.init(params()->burst_length_bins)
.name(name() + ".readBurstLengthHist")
.desc("Histogram of burst lengths of transmitted packets")
.flags(stats.disableBurstLengthHists ? nozero : pdf);
stats.writeBurstLengthHist
.init(params()->burst_length_bins)
.name(name() + ".writeBurstLengthHist")
.desc("Histogram of burst lengths of transmitted packets")
.flags(stats.disableBurstLengthHists ? nozero : pdf);
// Stats based on received responses
stats.readBandwidthHist
.init(params()->bandwidth_bins)
.name(name() + ".readBandwidthHist")
.desc("Histogram of read bandwidth per sample period (bytes/s)")
.flags(stats.disableBandwidthHists ? nozero : pdf);
stats.averageReadBW
.name(name() + ".averageReadBandwidth")
.desc("Average read bandwidth (bytes/s)")
.flags(stats.disableBandwidthHists ? nozero : pdf);
stats.totalReadBytes
.name(name() + ".totalReadBytes")
.desc("Number of bytes read")
.flags(stats.disableBandwidthHists ? nozero : pdf);
stats.averageReadBW = stats.totalReadBytes / simSeconds;
// Stats based on successfully sent requests
stats.writeBandwidthHist
.init(params()->bandwidth_bins)
.name(name() + ".writeBandwidthHist")
.desc("Histogram of write bandwidth (bytes/s)")
.flags(stats.disableBandwidthHists ? (pdf | nozero) : pdf);
stats.averageWriteBW
.name(name() + ".averageWriteBandwidth")
.desc("Average write bandwidth (bytes/s)")
.flags(stats.disableBandwidthHists ? nozero : pdf);
stats.totalWrittenBytes
.name(name() + ".totalWrittenBytes")
.desc("Number of bytes written")
.flags(stats.disableBandwidthHists ? nozero : pdf);
stats.averageWriteBW = stats.totalWrittenBytes / simSeconds;
stats.readLatencyHist
.init(params()->latency_bins)
.name(name() + ".readLatencyHist")
.desc("Read request-response latency")
.flags(stats.disableLatencyHists ? nozero : pdf);
stats.writeLatencyHist
.init(params()->latency_bins)
.name(name() + ".writeLatencyHist")
.desc("Write request-response latency")
.flags(stats.disableLatencyHists ? nozero : pdf);
stats.ittReadRead
.init(1, params()->itt_max_bin, params()->itt_max_bin /
params()->itt_bins)
.name(name() + ".ittReadRead")
.desc("Read-to-read inter transaction time")
.flags(stats.disableITTDists ? nozero : pdf);
stats.ittWriteWrite
.init(1, params()->itt_max_bin, params()->itt_max_bin /
params()->itt_bins)
.name(name() + ".ittWriteWrite")
.desc("Write-to-write inter transaction time")
.flags(stats.disableITTDists ? nozero : pdf);
stats.ittReqReq
.init(1, params()->itt_max_bin, params()->itt_max_bin /
params()->itt_bins)
.name(name() + ".ittReqReq")
.desc("Request-to-request inter transaction time")
.flags(stats.disableITTDists ? nozero : pdf);
stats.outstandingReadsHist
.init(params()->outstanding_bins)
.name(name() + ".outstandingReadsHist")
.desc("Outstanding read transactions")
.flags(stats.disableOutstandingHists ? nozero : pdf);
stats.outstandingWritesHist
.init(params()->outstanding_bins)
.name(name() + ".outstandingWritesHist")
.desc("Outstanding write transactions")
.flags(stats.disableOutstandingHists ? nozero : pdf);
stats.readTransHist
.init(params()->transaction_bins)
.name(name() + ".readTransHist")
.desc("Histogram of read transactions per sample period")
.flags(stats.disableTransactionHists ? nozero : pdf);
stats.writeTransHist
.init(params()->transaction_bins)
.name(name() + ".writeTransHist")
.desc("Histogram of read transactions per sample period")
.flags(stats.disableTransactionHists ? nozero : pdf);
stats.readAddrDist
.init(0)
.name(name() + ".readAddrDist")
.desc("Read address distribution")
.flags(stats.disableAddrDists ? nozero : pdf);
stats.writeAddrDist
.init(0)
.name(name() + ".writeAddrDist")
.desc("Write address distribution")
.flags(stats.disableAddrDists ? nozero : pdf);
}
void
CommMonitor::samplePeriodic()
{
// the periodic stats update runs on the granularity of sample
// periods, but in combination with this there may also be a
// external resets and dumps of the stats (through schedStatEvent)
// causing the stats themselves to capture less than a sample
// period
// only capture if we have not reset the stats during the last
// sample period
if (simTicks.value() >= samplePeriodTicks) {
if (!stats.disableTransactionHists) {
stats.readTransHist.sample(stats.readTrans);
stats.writeTransHist.sample(stats.writeTrans);
}
if (!stats.disableBandwidthHists) {
stats.readBandwidthHist.sample(stats.readBytes / samplePeriod);
stats.writeBandwidthHist.sample(stats.writtenBytes / samplePeriod);
}
if (!stats.disableOutstandingHists) {
stats.outstandingReadsHist.sample(stats.outstandingReadReqs);
stats.outstandingWritesHist.sample(stats.outstandingWriteReqs);
}
}
// reset the sampled values
stats.readTrans = 0;
stats.writeTrans = 0;
stats.readBytes = 0;
stats.writtenBytes = 0;
schedule(samplePeriodicEvent, curTick() + samplePeriodTicks);
}
void
CommMonitor::startup()
{
schedule(samplePeriodicEvent, curTick() + samplePeriodTicks);
}