dram_gen.cc

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#include "cpu/testers/traffic_gen/dram_gen.hh"
 
#include <algorithm>
 
#include "base/trace.hh"
#include "debug/TrafficGen.hh"
#include "enums/AddrMap.hh"
 
namespace gem5
{
 
DramGen::DramGen(SimObject &obj,
                 RequestorID requestor_id, Tick _duration,
                 Addr start_addr, Addr end_addr,
                 Addr _blocksize, Addr cacheline_size,
                 Tick min_period, Tick max_period,
                 uint8_t read_percent, Addr data_limit,
                 unsigned int num_seq_pkts, unsigned int page_size,
                 unsigned int nbr_of_banks_DRAM,
                 unsigned int nbr_of_banks_util,
                 enums::AddrMap addr_mapping,
                 unsigned int nbr_of_ranks)
        : RandomGen(obj, requestor_id, _duration, start_addr, end_addr,
          _blocksize, cacheline_size, min_period, max_period,
          read_percent, data_limit),
          numSeqPkts(num_seq_pkts), countNumSeqPkts(0), addr(0),
          isRead(true), pageSize(page_size),
          pageBits(floorLog2(page_size / _blocksize)),
          bankBits(floorLog2(nbr_of_banks_DRAM)),
          blockBits(floorLog2(_blocksize)),
          nbrOfBanksDRAM(nbr_of_banks_DRAM),
          nbrOfBanksUtil(nbr_of_banks_util), addrMapping(addr_mapping),
          rankBits(floorLog2(nbr_of_ranks)),
          nbrOfRanks(nbr_of_ranks)
{
    if (nbr_of_banks_util > nbr_of_banks_DRAM)
        fatal("Attempting to use more banks (%d) than "
              "what is available (%d)\n",
              nbr_of_banks_util, nbr_of_banks_DRAM);
}
DramGen::DramGen(SimObject &obj, {…}
 
PacketPtr
DramGen::getNextPacket()
{
    // if this is the first of the packets in series to be generated,
    // start counting again
    if (countNumSeqPkts == 0) {
        countNumSeqPkts = numSeqPkts;
 
        // choose if we generate a read or a write here
        isRead = readPercent != 0 &&
            (readPercent == 100 || rng->random(0, 100) < readPercent);
 
        assert((readPercent == 0 && !isRead) ||
               (readPercent == 100 && isRead) ||
               readPercent != 100);
 
        // pick a random bank
        unsigned int new_bank =
            rng->random<unsigned int>(0, nbrOfBanksUtil - 1);
 
        // pick a random rank
        unsigned int new_rank =
            rng->random<unsigned int>(0, nbrOfRanks - 1);
 
        // Generate the start address of the command series
        // routine will update addr variable with bank, rank, and col
        // bits updated for random traffic mode
        genStartAddr(new_bank, new_rank);
 
    } else {
        // increment the column by one
        if (addrMapping == enums::RoRaBaCoCh ||
            addrMapping == enums::RoRaBaChCo)
            // Simply increment addr by blocksize to increment
            // the column by one
            addr += blocksize;
 
        else if (addrMapping == enums::RoCoRaBaCh) {
            // Explicity increment the column bits
            unsigned int new_col = ((addr / blocksize /
                                       nbrOfBanksDRAM / nbrOfRanks) %
                                   (pageSize / blocksize)) + 1;
            replaceBits(addr, blockBits + bankBits + rankBits + pageBits - 1,
                        blockBits + bankBits + rankBits, new_col);
        }
    }
 
    DPRINTF(TrafficGen, "DramGen::getNextPacket: %c to addr %#x, "
            "size %d, countNumSeqPkts: %d, numSeqPkts: %d\n",
            isRead ? 'r' : 'w', addr, blocksize, countNumSeqPkts, numSeqPkts);
 
    // create a new request packet
    PacketPtr pkt = getPacket(addr, blocksize,
                              isRead ? MemCmd::ReadReq : MemCmd::WriteReq);
 
    // add the amount of data manipulated to the total
    dataManipulated += blocksize;
 
    // subtract the number of packets remained to be generated
    --countNumSeqPkts;
 
    // return the generated packet
    return pkt;
}
DramGen::getNextPacket() {…}
 
void
DramGen::genStartAddr(unsigned int new_bank, unsigned int new_rank)
{
    // start by picking a random address in the range
    addr = rng->random<Addr>(startAddr, endAddr - 1);
 
    // round down to start address of a block, i.e. a DRAM burst
    addr -= addr % blocksize;
 
    // insert the bank bits at the right spot, and align the
    // address to achieve the required hit length, this involves
    // finding the appropriate start address such that all
    // sequential packets target successive columns in the same
    // page
 
    // for example, if we have a stride size of 192B, which means
    // for LPDDR3 where burstsize = 32B we have numSeqPkts = 6,
    // the address generated previously can be such that these
    // 192B cross the page boundary, hence it needs to be aligned
    // so that they all belong to the same page for page hit
    unsigned int columns_per_page = pageSize / blocksize;
 
    // pick a random column, but ensure that there is room for
    // numSeqPkts sequential columns in the same page
    unsigned int new_col =
        rng->random<unsigned int>(0, columns_per_page - numSeqPkts);
 
    if (addrMapping == enums::RoRaBaCoCh ||
        addrMapping == enums::RoRaBaChCo) {
        // Block bits, then page bits, then bank bits, then rank bits
        replaceBits(addr, blockBits + pageBits + bankBits - 1,
                    blockBits + pageBits, new_bank);
        replaceBits(addr, blockBits + pageBits - 1, blockBits, new_col);
        if (rankBits != 0) {
            replaceBits(addr, blockBits + pageBits + bankBits +rankBits - 1,
                        blockBits + pageBits + bankBits, new_rank);
        }
    } else if (addrMapping == enums::RoCoRaBaCh) {
        // Block bits, then bank bits, then rank bits, then page bits
        replaceBits(addr, blockBits + bankBits - 1, blockBits, new_bank);
        replaceBits(addr, blockBits + bankBits + rankBits + pageBits - 1,
                    blockBits + bankBits + rankBits, new_col);
        if (rankBits != 0) {
            replaceBits(addr, blockBits + bankBits + rankBits - 1,
                        blockBits + bankBits, new_rank);
        }
    }
}
DramGen::genStartAddr(unsigned int new_bank, unsigned int new_rank) {…}
 
} // namespace gem5