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.

8 files changed, 129 insertions, 3 deletions

diff --git a/src/mem/cache/blk.hh b/src/mem/cache/blk.hh
index 4a89f3892..47cd305c0 100644
--- a/src/mem/cache/blk.hh
+++ b/src/mem/cache/blk.hh
@@ -80,6 +80,9 @@ enum CacheBlkStatusBits {
 class CacheBlk
 {
   public:
+    /** Task Id associated with this block */
+    uint32_t task_id;
+
     /** The address space ID of this block. */
     int asid;
     /** Data block tag value. */
@@ -119,6 +122,8 @@ class CacheBlk
     /** holds the source requestor ID for this block. */
     int srcMasterId;
 
+    Tick tickInserted;
+
   protected:
     /**
      * Represents that the indicated thread context has a "lock" on
@@ -162,9 +167,11 @@ class CacheBlk
   public:
 
     CacheBlk()
-        : asid(-1), tag(0), data(0) ,size(0), status(0), whenReady(0),
+        : task_id(ContextSwitchTaskId::Unknown),
+          asid(-1), tag(0), data(0) ,size(0), status(0), whenReady(0),
           set(-1), isTouched(false), refCount(0),
-          srcMasterId(Request::invldMasterId)
+          srcMasterId(Request::invldMasterId),
+          tickInserted(0)
     {}
 
     /**
@@ -182,6 +189,7 @@ class CacheBlk
         whenReady = rhs.whenReady;
         set = rhs.set;
         refCount = rhs.refCount;
+        task_id = rhs.task_id;
         return *this;
     }
 
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index 6d7011819..e86b3d704 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -1074,6 +1074,11 @@ Cache<TagStore>::writebackBlk(BlkType *blk)
     Request *writebackReq =
         new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
                 Request::wbMasterId);
+
+    writebackReq->taskId(blk->task_id);
+    blk->task_id= ContextSwitchTaskId::Unknown;
+    blk->tickInserted = curTick();
+
     PacketPtr writeback = new Packet(writebackReq, MemCmd::Writeback);
     if (blk->isWritable()) {
         writeback->setSupplyExclusive();
@@ -1120,6 +1125,7 @@ Cache<TagStore>::writebackVisitor(BlkType &blk)
 
         Request request(tags->regenerateBlkAddr(blk.tag, blk.set),
                         blkSize, 0, Request::funcMasterId);
+        request.taskId(blk.task_id);
 
         Packet packet(&request, MemCmd::WriteReq);
         packet.dataStatic(blk.data);
diff --git a/src/mem/cache/prefetch/base.cc b/src/mem/cache/prefetch/base.cc
index 6463f78f8..ed7b63f82 100644
--- a/src/mem/cache/prefetch/base.cc
+++ b/src/mem/cache/prefetch/base.cc
@@ -247,6 +247,7 @@ BasePrefetcher::notify(PacketPtr &pkt, Tick tick)
 
             // create a prefetch memreq
             Request *prefetchReq = new Request(*addrIter, blkSize, 0, masterId);
+            prefetchReq->taskId(ContextSwitchTaskId::Prefetcher);
             PacketPtr prefetch =
                 new Packet(prefetchReq, MemCmd::HardPFReq);
             prefetch->allocate();
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.
      *
diff --git a/src/mem/request.hh b/src/mem/request.hh
index 54b671645..fb21e3ff3 100644
--- a/src/mem/request.hh
+++ b/src/mem/request.hh
@@ -219,6 +219,11 @@ class Request
      */
     Tick _time;
 
+    /**
+     * The task id associated with this request
+     */
+    uint32_t _taskId;
+
     /** The address space ID. */
     int _asid;
 
@@ -244,7 +249,8 @@ class Request
      *  default constructor.)
      */
     Request()
-        : translateDelta(0), accessDelta(0), depth(0)
+        : _taskId(ContextSwitchTaskId::Unknown),
+        translateDelta(0), accessDelta(0), depth(0)
     {}
 
     /**
@@ -253,16 +259,19 @@ class Request
      * These fields are adequate to perform a request. 
      */
     Request(Addr paddr, int size, Flags flags, MasterID mid)
+        : _taskId(ContextSwitchTaskId::Unknown)
     {
         setPhys(paddr, size, flags, mid);
     }
 
     Request(Addr paddr, int size, Flags flags, MasterID mid, Tick time)
+        : _taskId(ContextSwitchTaskId::Unknown)
     {
         setPhys(paddr, size, flags, mid, time);
     }
 
     Request(Addr paddr, int size, Flags flags, MasterID mid, Tick time, Addr pc)
+        : _taskId(ContextSwitchTaskId::Unknown)
     {
         setPhys(paddr, size, flags, mid, time);
         privateFlags.set(VALID_PC);
@@ -271,6 +280,7 @@ class Request
 
     Request(int asid, Addr vaddr, int size, Flags flags, MasterID mid, Addr pc,
             int cid, ThreadID tid)
+        : _taskId(ContextSwitchTaskId::Unknown)
     {
         setVirt(asid, vaddr, size, flags, mid, pc);
         setThreadContext(cid, tid);
@@ -477,6 +487,17 @@ class Request
         return _masterId;
     }
 
+    uint32_t
+    taskId() const
+    {
+        return _taskId;
+    }
+
+    void
+    taskId(uint32_t id) {
+        _taskId = id;
+    }
+
     /** Accessor function for asid.*/
     int
     getAsid()