mem-ruby: Minor Ruby Prefetcher fixes

Minor fixes to the Ruby stride prefetcher. This includes removing unused
statistics and changing where/when some statistics are updated.

Change-Id: If758bf009f53fad277cb3cd754d57a0b10737599
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24363
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

diff --git a/src/mem/ruby/structures/Prefetcher.cc b/src/mem/ruby/structures/Prefetcher.cc
index 70b30352ea73abaff086e7effaee39d3be0e7759..a8b2d855710dab4c36c02815c2446062bde2d21f 100644 (file)
--- a/src/mem/ruby/structures/Prefetcher.cc
+++ b/src/mem/ruby/structures/Prefetcher.cc
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2020 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 1999-2012 Mark D. Hill and David A. Wood
  * All rights reserved.
  *
@@ -105,19 +117,9 @@ Prefetcher::regStats()
         .desc("number of prefetch requests made")
         ;
 
-    numPrefetchAccepted
-        .name(name() + ".prefetches_accepted")
-        .desc("number of prefetch requests accepted")
-        ;
-
-    numDroppedPrefetches
-        .name(name() + ".dropped_prefetches")
-        .desc("number of prefetch requests dropped")
-        ;
-
     numHits
         .name(name() + ".hits")
-        .desc("number of prefetched blocks accessed")
+        .desc("number of prefetched blocks accessed (for the first time)")
         ;
 
     numPartialHits
@@ -157,7 +159,7 @@ Prefetcher::observeMiss(Addr address, const RubyRequestType& type)
                 // The controller has issued the prefetch request,
                 // but the request for the block arrived earlier.
                 numPartialHits++;
-                observePfHit(line_addr);
+                observePfMiss(line_addr);
                 return;
             }
         } else {
@@ -242,16 +244,17 @@ Prefetcher::issueNextPrefetch(Addr address, PrefetchEntry *stream)
 
     // possibly stop prefetching at page boundaries
     if (page_addr != pageAddress(line_addr)) {
-        numPagesCrossed++;
         if (!m_prefetch_cross_pages) {
             // Deallocate the stream since we are not prefetching
             // across page boundries
             stream->m_is_valid = false;
             return;
         }
+        numPagesCrossed++;
     }
 
     // launch next prefetch
+    numPrefetchRequested++;
     stream->m_address = line_addr;
     stream->m_use_time = m_controller->curCycle();
     DPRINTF(RubyPrefetcher, "Requesting prefetch for %#x\n", line_addr);
@@ -308,12 +311,12 @@ Prefetcher::initializeStream(Addr address, int stride,
         line_addr = makeNextStrideAddress(line_addr, stride);
         // possibly stop prefetching at page boundaries
         if (page_addr != pageAddress(line_addr)) {
-            numPagesCrossed++;
             if (!m_prefetch_cross_pages) {
                 // deallocate this stream prefetcher
                 mystream->m_is_valid = false;
                 return;
             }
+            numPagesCrossed++;
         }
 
         // launch prefetch

diff --git a/src/mem/ruby/structures/Prefetcher.hh b/src/mem/ruby/structures/Prefetcher.hh
index 9c3c06851fe6a3eaeb3dab6e56f921c1e0364d6c..89c0186a76ada62a4e460dee6b73e29ba0b59ba9 100644 (file)
--- a/src/mem/ruby/structures/Prefetcher.hh
+++ b/src/mem/ruby/structures/Prefetcher.hh
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2020 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 1999-2012 Mark D. Hill and David A. Wood
  * All rights reserved.
  *
@@ -166,7 +178,7 @@ class Prefetcher : public SimObject
         //! have been hit
         uint32_t *m_unit_filter_hit;
 
-        //! a negative nit stride filter array: helps reduce BW requirement
+        //! a negative unit stride filter array: helps reduce BW requirement
         //! of prefetching
         std::vector<Addr> m_negative_filter;
         /// a round robin pointer into the negative filter group
@@ -199,10 +211,6 @@ class Prefetcher : public SimObject
         Stats::Scalar numAllocatedStreams;
         //! Count of prefetch requests made
         Stats::Scalar numPrefetchRequested;
-        //! Count of prefetch requests accepted
-        Stats::Scalar numPrefetchAccepted;
-        //! Count of prefetches dropped
-        Stats::Scalar numDroppedPrefetches;
         //! Count of successful prefetches
         Stats::Scalar numHits;
         //! Count of partial successful prefetches

diff --git a/src/mem/ruby/structures/RubyPrefetcher.py b/src/mem/ruby/structures/RubyPrefetcher.py
index a66bf4d293adc689e00a64aec5ad90ccb3988520..9d2803b34567c0b3fd759e154bac370160cf4156 100644 (file)
--- a/src/mem/ruby/structures/RubyPrefetcher.py
+++ b/src/mem/ruby/structures/RubyPrefetcher.py
@@ -1,3 +1,15 @@
+# Copyright (c) 2020 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
 # Copyright (c) 2012 Mark D. Hill and David A. Wood
 # All rights reserved.
 #
@@ -37,7 +49,6 @@ class Prefetcher(SimObject):
 
     num_streams = Param.UInt32(4,
         "Number of prefetch streams to be allocated")
-    pf_per_stream = Param.UInt32(1, "Number of prefetches per stream")
     unit_filter  = Param.UInt32(8,
         "Number of entries in the unit filter array")
     nonunit_filter = Param.UInt32(8,