Daniel Carvalho has submitted this change and it was merged. (
https://gem5-review.googlesource.com/c/public/gem5/+/11103 )
Change subject: mem-cache: Add compression stats
......................................................................
mem-cache: Add compression stats
Add compression statistics to the compressors. It tracks
the number of blocks that can fit into a certain power
of two size, and the number of decompressions.
For example, if a block is compressed to 100 bits, it will
belong to the 128-bits compression size. Although it could
also fit bigger sizes, they are not taken into account for
the stats (i.e., the 100-bit compression will fit only the
128-bits size, not 256 or higher).
We save stats for compressions that fail (i.e., compressed
size is bigger than original cache line size).
Change-Id: Idab71a40a660e33259908ccd880e42a880b5ee06
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/11103
Tested-by: kokoro <noreply+kok...@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikole...@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikole...@arm.com>
---
M src/mem/cache/compressors/base.cc
M src/mem/cache/compressors/base.hh
2 files changed, 42 insertions(+), 0 deletions(-)
Approvals:
Nikos Nikoleris: Looks good to me, approved; Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/mem/cache/compressors/base.cc
b/src/mem/cache/compressors/base.cc
index 2991dfe..1ba2677 100644
--- a/src/mem/cache/compressors/base.cc
+++ b/src/mem/cache/compressors/base.cc
@@ -36,6 +36,7 @@
#include <algorithm>
#include <cstdint>
+#include <string>
#include "debug/CacheComp.hh"
#include "mem/cache/tags/super_blk.hh"
@@ -100,6 +101,9 @@
// Get compression size
comp_size_bits = comp_data->getSizeBits();
+ // Update stats
+ compressionSize[std::ceil(std::log2(comp_size_bits))]++;
+
// Print debug information
DPRINTF(CacheComp, "Compressed cache line from %d to %d bits. " \
"Compression latency: %llu, decompression latency: %llu\n",
@@ -140,3 +144,23 @@
static_cast<CompressionBlk*>(blk)->setSizeBits(size_bits);
}
+void
+BaseCacheCompressor::regStats()
+{
+ SimObject::regStats();
+
+ // We also store when compression is bigger than original block size
+ compressionSize
+ .init(std::log2(blkSize*8) + 2)
+ .name(name() + ".compression_size")
+ .desc("Number of blocks that were compressed to this power of" \
+ "two size.")
+ ;
+
+ for (unsigned i = 0; i <= std::log2(blkSize*8) + 1; ++i) {
+ compressionSize.subname(i, std::to_string(1 << i));
+ compressionSize.subdesc(i, "Number of blocks that compressed to
fit " \
+ "in " + std::to_string(1 << i) + "
bits");
+ }
+}
+
diff --git a/src/mem/cache/compressors/base.hh
b/src/mem/cache/compressors/base.hh
index 1a8c82c..a19a072 100644
--- a/src/mem/cache/compressors/base.hh
+++ b/src/mem/cache/compressors/base.hh
@@ -40,6 +40,7 @@
#include <cstdint>
+#include "base/statistics.hh"
#include "base/types.hh"
#include "sim/sim_object.hh"
@@ -64,6 +65,18 @@
const std::size_t blkSize;
/**
+ * @defgroup CompressionStats Compression specific statistics.
+ * @{
+ */
+
+ /** Number of blocks that were compressed to this power of two size. */
+ Stats::Vector compressionSize;
+
+ /**
+ * @}
+ */
+
+ /**
* Apply the compression process to the cache line.
* Returns the number of cycles used by the compressor, however it is
* usually covered by a good pipelined execution, and is currently
ignored.
@@ -136,6 +149,11 @@
* @param size_bits The block size.
*/
static void setSizeBits(CacheBlk* blk, const std::size_t size_bits);
+
+ /**
+ * Register local statistics.
+ */
+ void regStats() override;
};
class BaseCacheCompressor::CompressionData {
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: Idab71a40a660e33259908ccd880e42a880b5ee06
Gerrit-Change-Number: 11103
Gerrit-PatchSet: 20
Gerrit-Owner: Daniel Carvalho <oda...@yahoo.com.br>
Gerrit-Reviewer: Daniel Carvalho <oda...@yahoo.com.br>
Gerrit-Reviewer: Jason Lowe-Power <ja...@lowepower.com>
Gerrit-Reviewer: Nikos Nikoleris <nikos.nikole...@arm.com>
Gerrit-Reviewer: kokoro <noreply+kok...@google.com>
Gerrit-MessageType: merged
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