From: Andreas Hansson <andreas.hansson@arm.com>
Date: Thu, 31 Jan 2013 12:49:13 +0000 (-0500)
Subject: mem: Separate out the different cases for DRAM bus busy time
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b7153e2a64bdb88cebe96e59b24d5597a3a42205;p=gem5.git

mem: Separate out the different cases for DRAM bus busy time

This patch changes how the data bus busy time is calculated such that
it is delayed to the actual scheduling time of the request as opposed
to being done as soon as possible.

This patch changes a bunch of statistics, and the stats update is
bundled together with the introruction of tFAW/tTAW and the named DRAM
configurations like DDR3 and LPDDR2.
---

diff --git a/src/mem/simple_dram.cc b/src/mem/simple_dram.cc
index 62825d139..305a7bcaf 100644
--- a/src/mem/simple_dram.cc
+++ b/src/mem/simple_dram.cc
@@ -299,13 +299,16 @@ SimpleDRAM::processWriteEvent()
 
         if (pageMgmt == Enums::open) {
             bank.openRow = dram_pkt->row;
-            bank.freeAt = schedTime + tBURST + accessLat;
+            bank.freeAt = schedTime + tBURST + std::max(accessLat, tCL);
+            busBusyUntil = bank.freeAt - tCL;
 
-            if (!rowHitFlag)
+            if (!rowHitFlag) {
                 bank.tRASDoneAt = bank.freeAt + tRP;
-
+                busBusyUntil = bank.freeAt - tCL - tRCD;
+            }
         } else if (pageMgmt == Enums::close) {
             bank.freeAt = schedTime + tBURST + accessLat + tRP + tRP;
+            busBusyUntil = bank.freeAt - tRP - tRP - tCL - tRCD;
             DPRINTF(DRAMWR, "processWriteEvent::bank.freeAt for "
                     "banks_id %d is %lld\n",
                     dram_pkt->rank * banksPerRank + dram_pkt->bank,
@@ -313,13 +316,8 @@ SimpleDRAM::processWriteEvent()
         } else
             panic("Unknown page management policy chosen\n");
 
-        // @todo: As of now, write goes on the databus asap, maybe
-        // be held up at bank. May want to change it to delay the
-        // schedTime itself.
-        busBusyUntil = schedTime + tBURST;
         DPRINTF(DRAMWR,"Done writing to address %lld\n",dram_pkt->addr);
 
-
         DPRINTF(DRAMWR,"schedtime is %lld, tBURST is %lld, "
                 "busbusyuntil is %lld\n",
                 schedTime, tBURST, busBusyUntil);
@@ -781,7 +779,8 @@ SimpleDRAM::estimateLatency(DRAMPacket* dram_pkt, Tick inTime)
     } else
         panic("No page management policy chosen\n");
 
-    DPRINTF(DRAM, "Returning %lld from estimateLatency()\n",accLat);
+    DPRINTF(DRAM, "Returning < %lld, %lld > from estimateLatency()\n",
+            bankLat, accLat);
 
     return make_pair(bankLat, accLat);
 }