gem5/src/mem/cache/base.hh
Andreas Hansson f6550b3d20 mem: Tighten up cache constness and scoping
This patch merely adopts a more strict use of const for the cache
member functions and variables, and also moves a large portion of the
member functions from public to protected.
2013-02-15 17:40:10 -05:00

587 lines
19 KiB
C++

/*
* Copyright (c) 2012 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.
*
* Copyright (c) 2003-2005 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
* Steve Reinhardt
* Ron Dreslinski
*/
/**
* @file
* Declares a basic cache interface BaseCache.
*/
#ifndef __BASE_CACHE_HH__
#define __BASE_CACHE_HH__
#include <algorithm>
#include <list>
#include <string>
#include <vector>
#include "base/misc.hh"
#include "base/statistics.hh"
#include "base/trace.hh"
#include "base/types.hh"
#include "debug/Cache.hh"
#include "debug/CachePort.hh"
#include "mem/cache/mshr_queue.hh"
#include "mem/mem_object.hh"
#include "mem/packet.hh"
#include "mem/qport.hh"
#include "mem/request.hh"
#include "params/BaseCache.hh"
#include "sim/eventq.hh"
#include "sim/full_system.hh"
#include "sim/sim_exit.hh"
#include "sim/system.hh"
class MSHR;
/**
* A basic cache interface. Implements some common functions for speed.
*/
class BaseCache : public MemObject
{
/**
* Indexes to enumerate the MSHR queues.
*/
enum MSHRQueueIndex {
MSHRQueue_MSHRs,
MSHRQueue_WriteBuffer
};
public:
/**
* Reasons for caches to be blocked.
*/
enum BlockedCause {
Blocked_NoMSHRs = MSHRQueue_MSHRs,
Blocked_NoWBBuffers = MSHRQueue_WriteBuffer,
Blocked_NoTargets,
NUM_BLOCKED_CAUSES
};
/**
* Reasons for cache to request a bus.
*/
enum RequestCause {
Request_MSHR = MSHRQueue_MSHRs,
Request_WB = MSHRQueue_WriteBuffer,
Request_PF,
NUM_REQUEST_CAUSES
};
protected:
/**
* A cache master port is used for the memory-side port of the
* cache, and in addition to the basic timing port that only sends
* response packets through a transmit list, it also offers the
* ability to schedule and send request packets (requests &
* writebacks). The send event is scheduled through requestBus,
* and the sendDeferredPacket of the timing port is modified to
* consider both the transmit list and the requests from the MSHR.
*/
class CacheMasterPort : public QueuedMasterPort
{
public:
/**
* Schedule a send of a request packet (from the MSHR). Note
* that we could already have a retry or a transmit list of
* responses outstanding.
*/
void requestBus(RequestCause cause, Tick time)
{
DPRINTF(CachePort, "Asserting bus request for cause %d\n", cause);
queue.schedSendEvent(time);
}
protected:
CacheMasterPort(const std::string &_name, BaseCache *_cache,
MasterPacketQueue &_queue) :
QueuedMasterPort(_name, _cache, _queue)
{ }
/**
* Memory-side port always snoops.
*
* @return always true
*/
virtual bool isSnooping() const { return true; }
};
/**
* A cache slave port is used for the CPU-side port of the cache,
* and it is basically a simple timing port that uses a transmit
* list for responses to the CPU (or connected master). In
* addition, it has the functionality to block the port for
* incoming requests. If blocked, the port will issue a retry once
* unblocked.
*/
class CacheSlavePort : public QueuedSlavePort
{
public:
/** Do not accept any new requests. */
void setBlocked();
/** Return to normal operation and accept new requests. */
void clearBlocked();
protected:
CacheSlavePort(const std::string &_name, BaseCache *_cache,
const std::string &_label);
/** A normal packet queue used to store responses. */
SlavePacketQueue queue;
bool blocked;
bool mustSendRetry;
private:
EventWrapper<SlavePort, &SlavePort::sendRetry> sendRetryEvent;
};
CacheSlavePort *cpuSidePort;
CacheMasterPort *memSidePort;
protected:
/** Miss status registers */
MSHRQueue mshrQueue;
/** Write/writeback buffer */
MSHRQueue writeBuffer;
MSHR *allocateBufferInternal(MSHRQueue *mq, Addr addr, int size,
PacketPtr pkt, Tick time, bool requestBus)
{
MSHR *mshr = mq->allocate(addr, size, pkt, time, order++);
if (mq->isFull()) {
setBlocked((BlockedCause)mq->index);
}
if (requestBus) {
requestMemSideBus((RequestCause)mq->index, time);
}
return mshr;
}
void markInServiceInternal(MSHR *mshr, PacketPtr pkt)
{
MSHRQueue *mq = mshr->queue;
bool wasFull = mq->isFull();
mq->markInService(mshr, pkt);
if (wasFull && !mq->isFull()) {
clearBlocked((BlockedCause)mq->index);
}
}
/**
* Write back dirty blocks in the cache using functional accesses.
*/
virtual void memWriteback() = 0;
/**
* Invalidates all blocks in the cache.
*
* @warn Dirty cache lines will not be written back to
* memory. Make sure to call functionalWriteback() first if you
* want the to write them to memory.
*/
virtual void memInvalidate() = 0;
/**
* Determine if there are any dirty blocks in the cache.
*
* \return true if at least one block is dirty, false otherwise.
*/
virtual bool isDirty() const = 0;
/** Block size of this cache */
const unsigned blkSize;
/**
* The latency of a hit in this device.
*/
const Cycles hitLatency;
/**
* The latency of sending reponse to its upper level cache/core on a
* linefill. In most contemporary processors, the return path on a cache
* miss is much quicker that the hit latency. The responseLatency parameter
* tries to capture this latency.
*/
const Cycles responseLatency;
/** The number of targets for each MSHR. */
const int numTarget;
/** Do we forward snoops from mem side port through to cpu side port? */
const bool forwardSnoops;
/** Is this cache a toplevel cache (e.g. L1, I/O cache). If so we should
* never try to forward ownership and similar optimizations to the cpu
* side */
const bool isTopLevel;
/**
* Bit vector of the blocking reasons for the access path.
* @sa #BlockedCause
*/
uint8_t blocked;
/** Increasing order number assigned to each incoming request. */
uint64_t order;
/** Stores time the cache blocked for statistics. */
Cycles blockedCycle;
/** Pointer to the MSHR that has no targets. */
MSHR *noTargetMSHR;
/** The number of misses to trigger an exit event. */
Counter missCount;
/**
* The address range to which the cache responds on the CPU side.
* Normally this is all possible memory addresses. */
const AddrRangeList addrRanges;
public:
/** System we are currently operating in. */
System *system;
// Statistics
/**
* @addtogroup CacheStatistics
* @{
*/
/** Number of hits per thread for each type of command. @sa Packet::Command */
Stats::Vector hits[MemCmd::NUM_MEM_CMDS];
/** Number of hits for demand accesses. */
Stats::Formula demandHits;
/** Number of hit for all accesses. */
Stats::Formula overallHits;
/** Number of misses per thread for each type of command. @sa Packet::Command */
Stats::Vector misses[MemCmd::NUM_MEM_CMDS];
/** Number of misses for demand accesses. */
Stats::Formula demandMisses;
/** Number of misses for all accesses. */
Stats::Formula overallMisses;
/**
* Total number of cycles per thread/command spent waiting for a miss.
* Used to calculate the average miss latency.
*/
Stats::Vector missLatency[MemCmd::NUM_MEM_CMDS];
/** Total number of cycles spent waiting for demand misses. */
Stats::Formula demandMissLatency;
/** Total number of cycles spent waiting for all misses. */
Stats::Formula overallMissLatency;
/** The number of accesses per command and thread. */
Stats::Formula accesses[MemCmd::NUM_MEM_CMDS];
/** The number of demand accesses. */
Stats::Formula demandAccesses;
/** The number of overall accesses. */
Stats::Formula overallAccesses;
/** The miss rate per command and thread. */
Stats::Formula missRate[MemCmd::NUM_MEM_CMDS];
/** The miss rate of all demand accesses. */
Stats::Formula demandMissRate;
/** The miss rate for all accesses. */
Stats::Formula overallMissRate;
/** The average miss latency per command and thread. */
Stats::Formula avgMissLatency[MemCmd::NUM_MEM_CMDS];
/** The average miss latency for demand misses. */
Stats::Formula demandAvgMissLatency;
/** The average miss latency for all misses. */
Stats::Formula overallAvgMissLatency;
/** The total number of cycles blocked for each blocked cause. */
Stats::Vector blocked_cycles;
/** The number of times this cache blocked for each blocked cause. */
Stats::Vector blocked_causes;
/** The average number of cycles blocked for each blocked cause. */
Stats::Formula avg_blocked;
/** The number of fast writes (WH64) performed. */
Stats::Scalar fastWrites;
/** The number of cache copies performed. */
Stats::Scalar cacheCopies;
/** Number of blocks written back per thread. */
Stats::Vector writebacks;
/** Number of misses that hit in the MSHRs per command and thread. */
Stats::Vector mshr_hits[MemCmd::NUM_MEM_CMDS];
/** Demand misses that hit in the MSHRs. */
Stats::Formula demandMshrHits;
/** Total number of misses that hit in the MSHRs. */
Stats::Formula overallMshrHits;
/** Number of misses that miss in the MSHRs, per command and thread. */
Stats::Vector mshr_misses[MemCmd::NUM_MEM_CMDS];
/** Demand misses that miss in the MSHRs. */
Stats::Formula demandMshrMisses;
/** Total number of misses that miss in the MSHRs. */
Stats::Formula overallMshrMisses;
/** Number of misses that miss in the MSHRs, per command and thread. */
Stats::Vector mshr_uncacheable[MemCmd::NUM_MEM_CMDS];
/** Total number of misses that miss in the MSHRs. */
Stats::Formula overallMshrUncacheable;
/** Total cycle latency of each MSHR miss, per command and thread. */
Stats::Vector mshr_miss_latency[MemCmd::NUM_MEM_CMDS];
/** Total cycle latency of demand MSHR misses. */
Stats::Formula demandMshrMissLatency;
/** Total cycle latency of overall MSHR misses. */
Stats::Formula overallMshrMissLatency;
/** Total cycle latency of each MSHR miss, per command and thread. */
Stats::Vector mshr_uncacheable_lat[MemCmd::NUM_MEM_CMDS];
/** Total cycle latency of overall MSHR misses. */
Stats::Formula overallMshrUncacheableLatency;
#if 0
/** The total number of MSHR accesses per command and thread. */
Stats::Formula mshrAccesses[MemCmd::NUM_MEM_CMDS];
/** The total number of demand MSHR accesses. */
Stats::Formula demandMshrAccesses;
/** The total number of MSHR accesses. */
Stats::Formula overallMshrAccesses;
#endif
/** The miss rate in the MSHRs pre command and thread. */
Stats::Formula mshrMissRate[MemCmd::NUM_MEM_CMDS];
/** The demand miss rate in the MSHRs. */
Stats::Formula demandMshrMissRate;
/** The overall miss rate in the MSHRs. */
Stats::Formula overallMshrMissRate;
/** The average latency of an MSHR miss, per command and thread. */
Stats::Formula avgMshrMissLatency[MemCmd::NUM_MEM_CMDS];
/** The average latency of a demand MSHR miss. */
Stats::Formula demandAvgMshrMissLatency;
/** The average overall latency of an MSHR miss. */
Stats::Formula overallAvgMshrMissLatency;
/** The average latency of an MSHR miss, per command and thread. */
Stats::Formula avgMshrUncacheableLatency[MemCmd::NUM_MEM_CMDS];
/** The average overall latency of an MSHR miss. */
Stats::Formula overallAvgMshrUncacheableLatency;
/** The number of times a thread hit its MSHR cap. */
Stats::Vector mshr_cap_events;
/** The number of times software prefetches caused the MSHR to block. */
Stats::Vector soft_prefetch_mshr_full;
Stats::Scalar mshr_no_allocate_misses;
/**
* @}
*/
/**
* Register stats for this object.
*/
virtual void regStats();
public:
typedef BaseCacheParams Params;
BaseCache(const Params *p);
~BaseCache() {}
virtual void init();
virtual BaseMasterPort &getMasterPort(const std::string &if_name,
PortID idx = InvalidPortID);
virtual BaseSlavePort &getSlavePort(const std::string &if_name,
PortID idx = InvalidPortID);
/**
* Query block size of a cache.
* @return The block size
*/
unsigned
getBlockSize() const
{
return blkSize;
}
Addr blockAlign(Addr addr) const { return (addr & ~(Addr(blkSize - 1))); }
const AddrRangeList &getAddrRanges() const { return addrRanges; }
MSHR *allocateMissBuffer(PacketPtr pkt, Tick time, bool requestBus)
{
assert(!pkt->req->isUncacheable());
return allocateBufferInternal(&mshrQueue,
blockAlign(pkt->getAddr()), blkSize,
pkt, time, requestBus);
}
MSHR *allocateWriteBuffer(PacketPtr pkt, Tick time, bool requestBus)
{
assert(pkt->isWrite() && !pkt->isRead());
return allocateBufferInternal(&writeBuffer,
pkt->getAddr(), pkt->getSize(),
pkt, time, requestBus);
}
MSHR *allocateUncachedReadBuffer(PacketPtr pkt, Tick time, bool requestBus)
{
assert(pkt->req->isUncacheable());
assert(pkt->isRead());
return allocateBufferInternal(&mshrQueue,
pkt->getAddr(), pkt->getSize(),
pkt, time, requestBus);
}
/**
* Returns true if the cache is blocked for accesses.
*/
bool isBlocked() const
{
return blocked != 0;
}
/**
* Marks the access path of the cache as blocked for the given cause. This
* also sets the blocked flag in the slave interface.
* @param cause The reason for the cache blocking.
*/
void setBlocked(BlockedCause cause)
{
uint8_t flag = 1 << cause;
if (blocked == 0) {
blocked_causes[cause]++;
blockedCycle = curCycle();
cpuSidePort->setBlocked();
}
blocked |= flag;
DPRINTF(Cache,"Blocking for cause %d, mask=%d\n", cause, blocked);
}
/**
* Marks the cache as unblocked for the given cause. This also clears the
* blocked flags in the appropriate interfaces.
* @param cause The newly unblocked cause.
* @warning Calling this function can cause a blocked request on the bus to
* access the cache. The cache must be in a state to handle that request.
*/
void clearBlocked(BlockedCause cause)
{
uint8_t flag = 1 << cause;
blocked &= ~flag;
DPRINTF(Cache,"Unblocking for cause %d, mask=%d\n", cause, blocked);
if (blocked == 0) {
blocked_cycles[cause] += curCycle() - blockedCycle;
cpuSidePort->clearBlocked();
}
}
/**
* Request the master bus for the given cause and time.
* @param cause The reason for the request.
* @param time The time to make the request.
*/
void requestMemSideBus(RequestCause cause, Tick time)
{
memSidePort->requestBus(cause, time);
}
/**
* Clear the master bus request for the given cause.
* @param cause The request reason to clear.
*/
void deassertMemSideBusRequest(RequestCause cause)
{
// Obsolete... we no longer signal bus requests explicitly so
// we can't deassert them. Leaving this in as a no-op since
// the prefetcher calls it to indicate that it no longer wants
// to request a prefetch, and someday that might be
// interesting again.
}
virtual unsigned int drain(DrainManager *dm);
virtual bool inCache(Addr addr) const = 0;
virtual bool inMissQueue(Addr addr) const = 0;
void incMissCount(PacketPtr pkt)
{
assert(pkt->req->masterId() < system->maxMasters());
misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
if (missCount) {
--missCount;
if (missCount == 0)
exitSimLoop("A cache reached the maximum miss count");
}
}
void incHitCount(PacketPtr pkt)
{
assert(pkt->req->masterId() < system->maxMasters());
hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
}
};
#endif //__BASE_CACHE_HH__