mem-cache: move unusedPrefetches stat to prefetcher

This stat belongs to prefetchers.
It has been renamed to pfUnused to match the naming of
exisiting prefetcher stats.

Change-Id: Iec350a62da544535dfc0c2527fcdf73217ae4db7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47599
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>

src/mem/cache/prefetch/base.cc

@@ -120,8 +120,11 @@ Base::setCache(BaseCache *_cache)
 Base::StatGroup::StatGroup(statistics::Group *parent)
   : statistics::Group(parent),
     ADD_STAT(pfIssued, statistics::units::Count::get(),
-        "number of hwpf issued")
+        "number of hwpf issued"),
+    ADD_STAT(pfUnused, statistics::units::Count::get(),
+             "number of HardPF blocks evicted w/o reference")
 {
+    pfUnused.flags(statistics::nozero);
 }
 
 

src/mem/cache/prefetch/base.hh

@@ -52,6 +52,7 @@
 #include "base/compiler.hh"
 #include "base/statistics.hh"
 #include "base/types.hh"
+#include "mem/cache/cache_blk.hh"
 #include "mem/packet.hh"
 #include "mem/request.hh"
 #include "sim/byteswap.hh"
@@ -328,6 +329,9 @@ class Base : public ClockedObject
     {
         StatGroup(statistics::Group *parent);
         statistics::Scalar pfIssued;
+        /** The number of times a HW-prefetched block is evicted w/o
+         * reference. */
+        statistics::Scalar pfUnused;
     } prefetchStats;
 
     /** Total prefetches issued */
@@ -358,6 +362,11 @@ class Base : public ClockedObject
 
     virtual Tick nextPrefetchReadyTime() const = 0;
 
+    void
+    prefetchUnused()
+    {
+        prefetchStats.pfUnused++;
+    }
 
     /**
      * Register probe points for this object.