gem5/src/cpu/testers/traffic_gen/strided_gen.cc

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#include "cpu/testers/traffic_gen/strided_gen.hh"

#include <algorithm>

#include "base/random.hh"
#include "base/trace.hh"
#include "debug/TrafficGen.hh"

namespace gem5
{

StridedGen::StridedGen(SimObject& obj, RequestorID requestor_id,
        Tick duration, Addr cacheline_size,
        Addr start_addr, Addr end_addr, Addr offset,
        Addr block_size, Addr superblock_size, Addr stride_size,
        Tick min_period, Tick max_period,
        uint8_t read_percent, Addr data_limit)
    : StochasticGen(obj, requestor_id, duration, start_addr, end_addr,
                    block_size, cacheline_size, min_period, max_period,
                    read_percent, data_limit),
    offset(offset), superblockSize(superblock_size), strideSize(stride_size),
    nextAddr(0), dataManipulated(0)
{
    assert(superblock_size % block_size == 0);
    assert(offset % superblock_size == 0);
    assert(stride_size % superblock_size == 0);
}

void
StridedGen::enter()
{
    // reset the address and the data counter
    nextAddr = startAddr + offset;
    dataManipulated = 0;
}

PacketPtr
StridedGen::getNextPacket()
{
    // choose if we generate a read or a write here
    bool isRead = readPercent != 0 &&
        (readPercent == 100 || random_mt.random(0, 100) < readPercent);

    assert((readPercent == 0 && !isRead) || (readPercent == 100 && isRead) ||
           readPercent != 100);

    DPRINTF(TrafficGen, "StridedGen::getNextPacket: %c to addr %x, size %d\n",
            isRead ? 'r' : 'w', nextAddr, blocksize);

    // Add the amount of data manipulated to the total
    dataManipulated += blocksize;

    PacketPtr pkt = getPacket(nextAddr, blocksize,
                              isRead ? MemCmd::ReadReq : MemCmd::WriteReq);

    // increment the address
    nextAddr += blocksize;

    // if we have completed reading a block we need to jump
    // (strideSize - blockSize) bytes to start reading the next block
    if ((nextAddr - (startAddr + offset)) % superblockSize == 0) {
        nextAddr += (strideSize - superblockSize);
    }

    // If we have reached the end of the address space, reset the
    // address to the start of the range
    if (nextAddr > endAddr) {
        DPRINTF(TrafficGen, "Wrapping address to the start of "
                "the range\n");
        nextAddr = startAddr + offset;
    }

    return pkt;
}

Tick
StridedGen::nextPacketTick(bool elastic, Tick delay) const
{
    // Check to see if we have reached the data limit. If dataLimit is
    // zero we do not have a data limit and therefore we will keep
    // generating requests for the entire residency in this state.
    if (dataLimit && dataManipulated >= dataLimit) {
        DPRINTF(TrafficGen, "Data limit for StridedGen reached.\n");
        // there are no more requests, therefore return MaxTick
        return MaxTick;
    } else {
        // return the time when the next request should take place
        Tick wait = random_mt.random(minPeriod, maxPeriod);

        // compensate for the delay experienced to not be elastic, by
        // default the value we generate is from the time we are
        // asked, so the elasticity happens automatically
        if (!elastic) {
            if (wait < delay)
                wait = 0;
            else
                wait -= delay;
        }

        return curTick() + wait;
    }
}

} // namespace gem5