mem: per-thread cache occupancy and per-block ages

This patch enables tracking of cache occupancy per thread along with
ages (in buckets) per cache blocks.  Cache occupancy stats are
recalculated on each stat dump.

4 files changed, 90 insertions, 0 deletions

diff --git a/src/mem/cache/tags/base.cc b/src/mem/cache/tags/base.cc
index 947bd05de..b669a5b06 100644
--- a/src/mem/cache/tags/base.cc
+++ b/src/mem/cache/tags/base.cc
@@ -125,5 +125,28 @@ BaseTags::regStats()
 
     avgOccs = occupancies / Stats::constant(numBlocks);
 
+    occupanciesTaskId
+        .init(ContextSwitchTaskId::NumTaskId)
+        .name(name() + ".occ_task_id_blocks")
+        .desc("Occupied blocks per task id")
+        .flags(nozero | nonan)
+        ;
+
+    ageTaskId
+        .init(ContextSwitchTaskId::NumTaskId, 5)
+        .name(name() + ".age_task_id_blocks")
+        .desc("Occupied blocks per task id")
+        .flags(nozero | nonan)
+        ;
+
+    percentOccsTaskId
+        .name(name() + ".occ_task_id_percent")
+        .desc("Percentage of cache occupancy per task id")
+        .flags(nozero)
+        ;
+
+    percentOccsTaskId = occupanciesTaskId / Stats::constant(numBlocks);
+
+    registerDumpCallback(new BaseTagsDumpCallback(this));
     registerExitCallback(new BaseTagsCallback(this));
 }
diff --git a/src/mem/cache/tags/base.hh b/src/mem/cache/tags/base.hh
index 8ce7d972a..e8c71f01f 100644
--- a/src/mem/cache/tags/base.hh
+++ b/src/mem/cache/tags/base.hh
@@ -121,6 +121,15 @@ class BaseTags : public ClockedObject
     /** Average occ % of each requestor using the cache */
     Stats::Formula avgOccs;
 
+    /** Occupancy of each context/cpu using the cache */
+    Stats::Vector occupanciesTaskId;
+
+    /** Occupancy of each context/cpu using the cache */
+    Stats::Vector2d ageTaskId;
+
+    /** Occ % of each context/cpu using the cache */
+    Stats::Formula percentOccsTaskId;
+
     /**
      * @}
      */
@@ -152,6 +161,11 @@ class BaseTags : public ClockedObject
     virtual void cleanupRefs() {}
 
     /**
+     * Computes stats just prior to dump event
+     */
+    virtual void computeStats() {}
+
+    /**
      *iterated through all blocks and clear all locks
      *Needed to clear all lock tracking at once
      */
@@ -171,4 +185,12 @@ class BaseTagsCallback : public Callback
     virtual void process() { tags->cleanupRefs(); };
 };
 
+class BaseTagsDumpCallback : public Callback
+{
+    BaseTags *tags;
+  public:
+    BaseTagsDumpCallback(BaseTags *t) : tags(t) {}
+    virtual void process() { tags->computeStats(); };
+};
+
 #endif //__BASE_TAGS_HH__
diff --git a/src/mem/cache/tags/lru.cc b/src/mem/cache/tags/lru.cc
index db0cc0839..6b05744af 100644
--- a/src/mem/cache/tags/lru.cc
+++ b/src/mem/cache/tags/lru.cc
@@ -176,6 +176,7 @@ LRU::insertBlock(PacketPtr pkt, BlkType *blk)
 {
     Addr addr = pkt->getAddr();
     MasterID master_id = pkt->req->masterId();
+    uint32_t task_id = pkt->req->taskId();
     if (!blk->isTouched) {
         tagsInUse++;
         blk->isTouched = true;
@@ -210,6 +211,8 @@ LRU::insertBlock(PacketPtr pkt, BlkType *blk)
     assert(master_id < cache->system->maxMasters());
     occupancies[master_id]++;
     blk->srcMasterId = master_id;
+    blk->task_id = task_id;
+    blk->tickInserted = curTick();
 
     unsigned set = extractSet(addr);
     sets[set].moveToHead(blk);
@@ -224,6 +227,8 @@ LRU::invalidate(BlkType *blk)
     assert(blk->srcMasterId < cache->system->maxMasters());
     occupancies[blk->srcMasterId]--;
     blk->srcMasterId = Request::invldMasterId;
+    blk->task_id = ContextSwitchTaskId::Unknown;
+    blk->tickInserted = curTick();
 
     // should be evicted before valid blocks
     unsigned set = blk->set;
@@ -270,3 +275,38 @@ LRU::cleanupRefs()
         }
     }
 }
+
+void
+LRU::computeStats()
+{
+    for (unsigned i = 0; i < ContextSwitchTaskId::NumTaskId; ++i) {
+        occupanciesTaskId[i] = 0;
+        for (unsigned j = 0; j < 5; ++j) {
+            ageTaskId[i][j] = 0;
+        }
+    }
+
+    for (unsigned i = 0; i < numSets * assoc; ++i) {
+        if (blks[i].isValid()) {
+            assert(blks[i].task_id < ContextSwitchTaskId::NumTaskId);
+            occupanciesTaskId[blks[i].task_id]++;
+            Tick age = curTick() - blks[i].tickInserted;
+            assert(age >= 0);
+
+            int age_index;
+            if (age / SimClock::Int::us < 10) { // <10us
+                age_index = 0;
+            } else if (age / SimClock::Int::us < 100) { // <100us
+                age_index = 1;
+            } else if (age / SimClock::Int::ms < 1) { // <1ms
+                age_index = 2;
+            } else if (age / SimClock::Int::ms < 10) { // <10ms
+                age_index = 3;
+            } else
+                age_index = 4; // >10ms
+
+            ageTaskId[blks[i].task_id][age_index]++;
+        }
+    }
+}
+
diff --git a/src/mem/cache/tags/lru.hh b/src/mem/cache/tags/lru.hh
index af7f8665d..68c29b754 100644
--- a/src/mem/cache/tags/lru.hh
+++ b/src/mem/cache/tags/lru.hh
@@ -253,6 +253,11 @@ public:
     virtual std::string print() const;
 
     /**
+     * Called prior to dumping stats to compute task occupancy
+     */
+    virtual void computeStats();
+
+    /**
      * Visit each block in the tag store and apply a visitor to the
      * block.
      *