From: Korey Sewell <ksewell@umich.edu>
Date: Fri, 4 Feb 2011 05:08:13 +0000 (-0500)
Subject: inorder: activity tracking bug
X-Git-Tag: stable_2012_02_02~617
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7f937e11e2779628002d063a368ee3101a32471d;p=gem5.git

inorder: activity tracking bug
Previous code was marking CPU activity on almost every cycle due to a bug in
tracking the status of pipeline stages. This disables the CPU from sleeping
on long latency stalls and increases simulation time
---

diff --git a/src/cpu/inorder/first_stage.cc b/src/cpu/inorder/first_stage.cc
index ae458c604..424d6b6a4 100644
--- a/src/cpu/inorder/first_stage.cc
+++ b/src/cpu/inorder/first_stage.cc
@@ -126,8 +126,10 @@ FirstStage::processStage(bool &status_change)
         if (tid >= 0) {
             DPRINTF(InOrderStage, "Processing [tid:%i]\n",tid);
             processThread(status_change, tid);
+            DPRINTF(InOrderStage, "Done Processing [tid:%i]\n",tid);
         } else {
             DPRINTF(InOrderStage, "No more threads to fetch from.\n");
+            break;
         }
     }
 
@@ -148,7 +150,7 @@ FirstStage::processInsts(ThreadID tid)
 {
     bool all_reqs_completed = true;
 
-    for (int insts_fetched = 0; 
+    for (int insts_fetched = instsProcessed;
          insts_fetched < stageWidth && canSendInstToStage(1); 
          insts_fetched++) {
 
@@ -200,8 +202,11 @@ FirstStage::processInsts(ThreadID tid)
                         "list.\n", tid, inst->seqNum);
                 insts[tid].push(inst);
             }
+            block(tid);
             break;
         } else if (!insts[tid].empty()){
+            DPRINTF(InOrderStage, "[tid:%u]: [sn:%u] Finished all "
+                    "requests for this stage.\n", tid, inst->seqNum);
             insts[tid].pop();
         }
 
@@ -210,7 +215,7 @@ FirstStage::processInsts(ThreadID tid)
 
     // Record that stage has written to the time buffer for activity
     // tracking.
-    if (toNextStageIndex) {
+    if (instsProcessed) {
         wroteToTimeBuffer = true;
     }
 }
diff --git a/src/cpu/inorder/pipeline_stage.cc b/src/cpu/inorder/pipeline_stage.cc
index 2ac402fae..710af5332 100644
--- a/src/cpu/inorder/pipeline_stage.cc
+++ b/src/cpu/inorder/pipeline_stage.cc
@@ -281,15 +281,15 @@ PipelineStage::block(ThreadID tid)
     // signalled fetch to unblock. In that case, there is no need to tell
     // fetch to block.
     if (stageStatus[tid] != Blocked) {
-        // Set the status to Blocked.
-        stageStatus[tid] = Blocked;
-
         if (stageStatus[tid] != Unblocking) {
-            if (prevStageValid)
-                toPrevStages->stageBlock[stageNum][tid] = true;
             wroteToTimeBuffer = true;
         }
 
+        stageStatus[tid] = Blocked;
+
+        if (prevStageValid)
+            toPrevStages->stageBlock[stageNum][tid] = true;
+
         return true;
     }
 
@@ -304,12 +304,12 @@ PipelineStage::blockDueToBuffer(ThreadID tid)
             "next stage.\n", tid);
 
     if (stageStatus[tid] != Blocked) {
-        // Set the status to Blocked.
-        stageStatus[tid] = Blocked;
-
         if (stageStatus[tid] != Unblocking) {
             wroteToTimeBuffer = true;
         }
+
+        // Set the status to Blocked.
+        stageStatus[tid] = Blocked;
     }
 }
 
@@ -595,18 +595,26 @@ PipelineStage::sortInsts()
 {
     if (prevStageValid) {
         int insts_from_prev_stage = prevStage->size;
+        int insts_from_cur_stage = skidSize();
+        DPRINTF(InOrderStage, "%i insts available from stage buffer %i. Stage "
+                "currently has %i insts from last cycle.\n",
+                insts_from_prev_stage, prevStageQueue->id(),
+                insts_from_cur_stage);
 
-        DPRINTF(InOrderStage, "%i insts available from stage buffer %i.\n",
-                insts_from_prev_stage, prevStageQueue->id());
-
+        int inserted_insts = 0;
         for (int i = 0; i < insts_from_prev_stage; ++i) {
+            if (inserted_insts + insts_from_cur_stage == stageWidth) {
+               DPRINTF(InOrderStage, "Stage %i has accepted all insts "
+                       "possible for this tick.\n");
+                break;
+            }
 
             if (prevStage->insts[i]->isSquashed()) {
                 DPRINTF(InOrderStage, "[tid:%i]: Ignoring squashed [sn:%i], "
                         "not inserting into stage buffer.\n",
                     prevStage->insts[i]->readTid(),
                     prevStage->insts[i]->seqNum);
-
+                prevStage->size--;
                 continue;
             }
 
@@ -622,7 +630,11 @@ PipelineStage::sortInsts()
 
             prevStage->insts[i] = cpu->dummyBufferInst;
 
+            prevStage->size--;
+
+            inserted_insts++;
         }
+        assert(prevStage->size == 0);
     }
 }
 
@@ -937,7 +949,7 @@ PipelineStage::processInsts(ThreadID tid)
 
     // Record that stage has written to the time buffer for activity
     // tracking.
-    if (toNextStageIndex) {
+    if (instsProcessed) {
         wroteToTimeBuffer = true;
     }
 }