From 0f33b2c1d5875aae036a9e2779f6e9c764e0f85e Mon Sep 17 00:00:00 2001 From: Andreas Sandberg Date: Wed, 2 May 2018 13:55:10 +0100 Subject: mem: Add a memory delay simulator Add a memory system component that delays traffic. The base functionality to delay packets is implemented in the abstract MemDelay class. This class exposes three methods that control packet delays: * delayReq(pkt) * delayResp(pkt) * delaySnoopResp(pkt) These methods should be specialized to implement delays for specific packet types. The class SimpleMemDelay uses the MemDelay base class to implement constant delays for read/write requests and responses. The intention is that these classes can be used for rapid prototyping of components that add a small fixed delay and the same throughput as the interconnect. I.e., any buffering done in the base class will be small and proportional to the introduced delay. Change-Id: I158cb85f20e32bfdbcbfed66a785b4b2dd47b628 Signed-off-by: Andreas Sandberg Reviewed-by: Nicholas Lindsey Reviewed-by: Nikos Nikoleris Reviewed-on: https://gem5-review.googlesource.com/11521 Reviewed-by: Daniel Carvalho Reviewed-by: Jason Lowe-Power Maintainer: Nikos Nikoleris --- src/mem/mem_delay.hh | 185 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 185 insertions(+) create mode 100644 src/mem/mem_delay.hh (limited to 'src/mem/mem_delay.hh') diff --git a/src/mem/mem_delay.hh b/src/mem/mem_delay.hh new file mode 100644 index 000000000..28c04052b --- /dev/null +++ b/src/mem/mem_delay.hh @@ -0,0 +1,185 @@ +/* + * Copyright (c) 2018 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: Andreas Sandberg + */ + +#ifndef __MEM_MEM_DELAY_HH__ +#define __MEM_MEM_DELAY_HH__ + +#include "mem/mem_object.hh" +#include "mem/qport.hh" + +struct MemDelayParams; +struct SimpleMemDelayParams; + +/** + * This abstract component provides a mechanism to delay + * packets. It can be spliced between arbitrary ports of the memory + * system and delays packets that pass through it. + * + * Specialisations of this abstract class should override at least one + * of delayReq, delayResp, deleySnoopReq, delaySnoopResp. These + * methods receive a PacketPtr as their argument and return a delay in + * Ticks. The base class implements an infinite buffer to hold delayed + * packets until they are ready. The intention is to use this + * component for rapid prototyping of other memory system components + * that introduce a packet processing delays. + * + * NOTE: Packets may be reordered if the delays aren't constant. + */ +class MemDelay : public MemObject +{ + + public: + MemDelay(const MemDelayParams *params); + + void init() override; + + protected: // Port interfaces + BaseMasterPort& getMasterPort(const std::string &if_name, + PortID idx = InvalidPortID) override; + + BaseSlavePort& getSlavePort(const std::string &if_name, + PortID idx = InvalidPortID) override; + + class MasterPort : public QueuedMasterPort + { + public: + MasterPort(const std::string &_name, MemDelay &_parent); + + protected: + bool recvTimingResp(PacketPtr pkt) override; + + void recvFunctionalSnoop(PacketPtr pkt) override; + + Tick recvAtomicSnoop(PacketPtr pkt) override; + + void recvTimingSnoopReq(PacketPtr pkt) override; + + void recvRangeChange() override { + parent.slavePort.sendRangeChange(); + } + + bool isSnooping() const override { + return parent.slavePort.isSnooping(); + } + + private: + MemDelay& parent; + }; + + class SlavePort : public QueuedSlavePort + { + public: + SlavePort(const std::string &_name, MemDelay &_parent); + + protected: + Tick recvAtomic(PacketPtr pkt) override; + bool recvTimingReq(PacketPtr pkt) override; + void recvFunctional(PacketPtr pkt) override; + bool recvTimingSnoopResp(PacketPtr pkt) override; + + AddrRangeList getAddrRanges() const override { + return parent.masterPort.getAddrRanges(); + } + + bool tryTiming(PacketPtr pkt) override { return true; } + + private: + + MemDelay& parent; + + }; + + bool checkFunctional(PacketPtr pkt); + + MasterPort masterPort; + SlavePort slavePort; + + ReqPacketQueue reqQueue; + RespPacketQueue respQueue; + SnoopRespPacketQueue snoopRespQueue; + + protected: + /** + * Delay a request by some number of ticks. + * + * @return Ticks to delay packet. + */ + virtual Tick delayReq(PacketPtr pkt) { return 0; } + + /** + * Delay a response by some number of ticks. + * + * @return Ticks to delay packet. + */ + virtual Tick delayResp(PacketPtr pkt) { return 0; } + + /** + * Delay a snoop response by some number of ticks. + * + * @return Ticks to delay packet. + */ + virtual Tick delaySnoopResp(PacketPtr pkt) { return 0; } +}; + +/** + * Delay packets by a constant time. Delays can be specified + * separately for read requests, read responses, write requests, and + * write responses. + * + * This class does not delay snoops or requests/responses that are + * neither reads or writes. + */ +class SimpleMemDelay : public MemDelay +{ + public: + SimpleMemDelay(const SimpleMemDelayParams *params); + + protected: + Tick delayReq(PacketPtr pkt) override; + Tick delayResp(PacketPtr pkt) override; + + protected: // Params + const Tick readReqDelay; + const Tick readRespDelay; + + const Tick writeReqDelay; + const Tick writeRespDelay; +}; + +#endif //__MEM_MEM_DELAY_HH__ -- cgit v1.2.3