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update DRAM simulation - reduce the latency of duplicate requests (simulate DRAM cache)

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This commit is contained in:
Blaise Tine
2020-12-03 07:30:19 -08:00
parent f3b1069ce8
commit b7a724410b
4 changed files with 37 additions and 19 deletions
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29
hw/simulate/simulator.cpp
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@@ -127,15 +127,17 @@ void Simulator::eval_dram_bus() {
return;
}
// schedule DRAM responses
// update DRAM responses schedule
for (auto& rsp : dram_rsp_vec_) {
if (rsp.cycles_left > 0)
rsp.cycles_left -= 1;
}
// schedule DRAM responses in FIFO order
std::list<dram_req_t>::iterator dram_rsp_it(dram_rsp_vec_.end());
for (auto it = dram_rsp_vec_.begin(), ie = dram_rsp_vec_.end(); it != ie; ++it) {
if (it->cycles_left > 0) {
it->cycles_left -= 1;
}
if ((dram_rsp_it == ie) && (it->cycles_left == 0)) {
dram_rsp_it = it;
}
if (!dram_rsp_vec_.empty()
&& (0 == dram_rsp_vec_.begin()->cycles_left)) {
dram_rsp_it = dram_rsp_vec_.begin();
}
// send DRAM response
@@ -180,9 +182,16 @@ void Simulator::eval_dram_bus() {
}
} else {
dram_req_t dram_req;
dram_req.tag = vortex_->dram_req_tag;
dram_req.tag = vortex_->dram_req_tag;
dram_req.addr = vortex_->dram_req_addr;
ram_->read(vortex_->dram_req_addr * GLOBAL_BLOCK_SIZE, GLOBAL_BLOCK_SIZE, dram_req.block.data());
dram_req.cycles_left = DRAM_LATENCY;
dram_req.cycles_left = DRAM_LATENCY;
for (auto& rsp : dram_rsp_vec_) {
if (dram_req.addr == rsp.addr) {
dram_req.cycles_left = rsp.cycles_left;
break;
}
}
dram_rsp_vec_.emplace_back(dram_req);
}
}