This patch tidies up random number generation to ensure that it is done consistently throughout the code base. In essence this involves a clean-up of Ruby, and some code simplifications in the traffic generator. As part of this patch a bunch of skewed distributions (off-by-one etc) have been fixed. Note that a single global random number generator is used, and that the object instantiation order will impact the behaviour (the sequence of numbers will be unaffected, but if module A calles random before module B then they would obviously see a different outcome). The dependency on the instantiation order is true in any case due to the execution-model of gem5, so we leave it as is. Also note that the global ranom generator is not thread safe at this point. Regressions using the memtest, TrafficGen or any Ruby tester are affected and will be updated accordingly.
425 lines
14 KiB
C++
425 lines
14 KiB
C++
/*
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* Copyright (c) 2012-2013 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Thomas Grass
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* Andreas Hansson
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* Sascha Bischoff
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* Neha Agarwal
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*/
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#include "base/random.hh"
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#include "base/trace.hh"
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#include "cpu/testers/traffic_gen/generators.hh"
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#include "debug/TrafficGen.hh"
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#include "proto/packet.pb.h"
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BaseGen::BaseGen(const std::string& _name, MasterID master_id, Tick _duration)
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: _name(_name), masterID(master_id), duration(_duration)
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{
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}
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PacketPtr
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BaseGen::getPacket(Addr addr, unsigned size, const MemCmd& cmd,
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Request::FlagsType flags)
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{
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// Create new request
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Request *req = new Request(addr, size, flags, masterID);
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// Embed it in a packet
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PacketPtr pkt = new Packet(req, cmd);
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uint8_t* pkt_data = new uint8_t[req->getSize()];
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pkt->dataDynamicArray(pkt_data);
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if (cmd.isWrite()) {
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memset(pkt_data, 0xA, req->getSize());
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}
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return pkt;
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}
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void
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LinearGen::enter()
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{
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// reset the address and the data counter
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nextAddr = startAddr;
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dataManipulated = 0;
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}
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PacketPtr
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LinearGen::getNextPacket()
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{
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// choose if we generate a read or a write here
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bool isRead = readPercent != 0 &&
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(readPercent == 100 || random_mt.random(0, 100) < readPercent);
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assert((readPercent == 0 && !isRead) || (readPercent == 100 && isRead) ||
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readPercent != 100);
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DPRINTF(TrafficGen, "LinearGen::getNextPacket: %c to addr %x, size %d\n",
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isRead ? 'r' : 'w', nextAddr, blocksize);
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// Add the amount of data manipulated to the total
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dataManipulated += blocksize;
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PacketPtr pkt = getPacket(nextAddr, blocksize,
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isRead ? MemCmd::ReadReq : MemCmd::WriteReq);
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// increment the address
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nextAddr += blocksize;
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// If we have reached the end of the address space, reset the
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// address to the start of the range
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if (nextAddr > endAddr) {
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DPRINTF(TrafficGen, "Wrapping address to the start of "
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"the range\n");
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nextAddr = startAddr;
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}
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return pkt;
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}
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Tick
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LinearGen::nextPacketTick(bool elastic, Tick delay) const
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{
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// Check to see if we have reached the data limit. If dataLimit is
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// zero we do not have a data limit and therefore we will keep
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// generating requests for the entire residency in this state.
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if (dataLimit && dataManipulated >= dataLimit) {
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DPRINTF(TrafficGen, "Data limit for LinearGen reached.\n");
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// there are no more requests, therefore return MaxTick
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return MaxTick;
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} else {
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// return the time when the next request should take place
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Tick wait = random_mt.random(minPeriod, maxPeriod);
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// compensate for the delay experienced to not be elastic, by
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// default the value we generate is from the time we are
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// asked, so the elasticity happens automatically
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if (!elastic) {
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if (wait < delay)
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wait = 0;
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else
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wait -= delay;
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}
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return curTick() + wait;
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}
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}
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void
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RandomGen::enter()
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{
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// reset the counter to zero
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dataManipulated = 0;
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}
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PacketPtr
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RandomGen::getNextPacket()
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{
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// choose if we generate a read or a write here
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bool isRead = readPercent != 0 &&
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(readPercent == 100 || random_mt.random(0, 100) < readPercent);
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assert((readPercent == 0 && !isRead) || (readPercent == 100 && isRead) ||
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readPercent != 100);
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// address of the request
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Addr addr = random_mt.random(startAddr, endAddr - 1);
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// round down to start address of block
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addr -= addr % blocksize;
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DPRINTF(TrafficGen, "RandomGen::getNextPacket: %c to addr %x, size %d\n",
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isRead ? 'r' : 'w', addr, blocksize);
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// add the amount of data manipulated to the total
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dataManipulated += blocksize;
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// create a new request packet
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return getPacket(addr, blocksize,
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isRead ? MemCmd::ReadReq : MemCmd::WriteReq);
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}
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PacketPtr
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DramGen::getNextPacket()
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{
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// if this is the first of the packets in series to be generated,
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// start counting again
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if (countNumSeqPkts == 0) {
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countNumSeqPkts = numSeqPkts;
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// choose if we generate a read or a write here
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isRead = readPercent != 0 &&
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(readPercent == 100 || random_mt.random(0, 100) < readPercent);
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assert((readPercent == 0 && !isRead) ||
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(readPercent == 100 && isRead) ||
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readPercent != 100);
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// start by picking a random address in the range
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addr = random_mt.random(startAddr, endAddr - 1);
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// round down to start address of a block, i.e. a DRAM burst
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addr -= addr % blocksize;
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// pick a random bank
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unsigned int new_bank =
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random_mt.random<unsigned int>(0, nbrOfBanksUtil - 1);
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// next, inser the bank bits at the right spot, and align the
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// address to achieve the required hit length, this involves
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// finding the appropriate start address such that all
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// sequential packets target successive columns in the same
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// page
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// for example, if we have a stride size of 192B, which means
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// for LPDDR3 where burstsize = 32B we have numSeqPkts = 6,
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// the address generated previously can be such that these
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// 192B cross the page boundary, hence it needs to be aligned
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// so that they all belong to the same page for page hit
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unsigned int columns_per_page = pageSize / blocksize;
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// pick a random column, but ensure that there is room for
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// numSeqPkts sequential columns in the same page
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unsigned int new_col =
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random_mt.random<unsigned int>(0, columns_per_page - numSeqPkts);
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if (addrMapping == 1) {
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// assuming block bits, then page bits, then bank bits
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replaceBits(addr, blockBits + pageBits + bankBits - 1,
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blockBits + pageBits, new_bank);
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replaceBits(addr, blockBits + pageBits - 1, blockBits, new_col);
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} else if (addrMapping == 0) {
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// assuming bank bits in the bottom
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replaceBits(addr, blockBits + bankBits - 1, blockBits, new_bank);
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replaceBits(addr, blockBits + bankBits + pageBits - 1,
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blockBits + bankBits, new_col);
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}
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} else {
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// increment the column by one
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if (addrMapping == 1)
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// column bits in the bottom, so just add a block
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addr += blocksize;
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else if (addrMapping == 0) {
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// column bits are above the bank bits, so increment the column bits
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unsigned int new_col = ((addr / blocksize / nbrOfBanksDRAM) %
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(pageSize / blocksize)) + 1;
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replaceBits(addr, blockBits + bankBits + pageBits - 1,
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blockBits + bankBits, new_col);
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}
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}
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DPRINTF(TrafficGen, "DramGen::getNextPacket: %c to addr %x, "
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"size %d, countNumSeqPkts: %d, numSeqPkts: %d\n",
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isRead ? 'r' : 'w', addr, blocksize, countNumSeqPkts, numSeqPkts);
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// create a new request packet
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PacketPtr pkt = getPacket(addr, blocksize,
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isRead ? MemCmd::ReadReq : MemCmd::WriteReq);
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// add the amount of data manipulated to the total
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dataManipulated += blocksize;
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// subtract the number of packets remained to be generated
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--countNumSeqPkts;
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// return the generated packet
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return pkt;
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}
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Tick
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RandomGen::nextPacketTick(bool elastic, Tick delay) const
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{
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// Check to see if we have reached the data limit. If dataLimit is
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// zero we do not have a data limit and therefore we will keep
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// generating requests for the entire residency in this state.
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if (dataLimit && dataManipulated >= dataLimit)
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{
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DPRINTF(TrafficGen, "Data limit for RandomGen reached.\n");
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// No more requests. Return MaxTick.
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return MaxTick;
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} else {
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// return the time when the next request should take place
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Tick wait = random_mt.random(minPeriod, maxPeriod);
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// compensate for the delay experienced to not be elastic, by
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// default the value we generate is from the time we are
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// asked, so the elasticity happens automatically
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if (!elastic) {
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if (wait < delay)
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wait = 0;
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else
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wait -= delay;
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}
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return curTick() + wait;
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}
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}
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TraceGen::InputStream::InputStream(const std::string& filename)
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: trace(filename)
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{
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init();
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}
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void
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TraceGen::InputStream::init()
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{
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// Create a protobuf message for the header and read it from the stream
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ProtoMessage::PacketHeader header_msg;
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if (!trace.read(header_msg)) {
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panic("Failed to read packet header from trace\n");
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if (header_msg.tick_freq() != SimClock::Frequency) {
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panic("Trace was recorded with a different tick frequency %d\n",
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header_msg.tick_freq());
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}
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}
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}
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void
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TraceGen::InputStream::reset()
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{
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trace.reset();
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init();
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}
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bool
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TraceGen::InputStream::read(TraceElement& element)
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{
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ProtoMessage::Packet pkt_msg;
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if (trace.read(pkt_msg)) {
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element.cmd = pkt_msg.cmd();
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element.addr = pkt_msg.addr();
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element.blocksize = pkt_msg.size();
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element.tick = pkt_msg.tick();
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element.flags = pkt_msg.has_flags() ? pkt_msg.flags() : 0;
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return true;
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}
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// We have reached the end of the file
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return false;
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}
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Tick
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TraceGen::nextPacketTick(bool elastic, Tick delay) const
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{
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if (traceComplete) {
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DPRINTF(TrafficGen, "No next tick as trace is finished\n");
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// We are at the end of the file, thus we have no more data in
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// the trace Return MaxTick to signal that there will be no
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// more transactions in this active period for the state.
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return MaxTick;
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}
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assert(nextElement.isValid());
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DPRINTF(TrafficGen, "Next packet tick is %d\n", tickOffset +
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nextElement.tick);
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// if the playback is supposed to be elastic, add the delay
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if (elastic)
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tickOffset += delay;
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return std::max(tickOffset + nextElement.tick, curTick());
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}
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void
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TraceGen::enter()
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{
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// update the trace offset to the time where the state was entered.
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tickOffset = curTick();
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// clear everything
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currElement.clear();
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// read the first element in the file and set the complete flag
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traceComplete = !trace.read(nextElement);
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}
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PacketPtr
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TraceGen::getNextPacket()
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{
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// shift things one step forward
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currElement = nextElement;
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nextElement.clear();
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// read the next element and set the complete flag
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traceComplete = !trace.read(nextElement);
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// it is the responsibility of the traceComplete flag to ensure we
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// always have a valid element here
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assert(currElement.isValid());
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DPRINTF(TrafficGen, "TraceGen::getNextPacket: %c %d %d %d 0x%x\n",
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currElement.cmd.isRead() ? 'r' : 'w',
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currElement.addr,
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currElement.blocksize,
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currElement.tick,
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currElement.flags);
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PacketPtr pkt = getPacket(currElement.addr + addrOffset,
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currElement.blocksize,
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currElement.cmd, currElement.flags);
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if (!traceComplete)
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DPRINTF(TrafficGen, "nextElement: %c addr %d size %d tick %d (%d)\n",
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nextElement.cmd.isRead() ? 'r' : 'w',
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nextElement.addr,
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nextElement.blocksize,
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nextElement.tick + tickOffset,
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nextElement.tick);
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return pkt;
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}
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void
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TraceGen::exit()
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{
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// Check if we reached the end of the trace file. If we did not
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// then we want to generate a warning stating that not the entire
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// trace was played.
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if (!traceComplete) {
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warn("Trace player %s was unable to replay the entire trace!\n",
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name());
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}
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// Clear any flags and start over again from the beginning of the
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// file
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trace.reset();
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}
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