Daniel Carvalho has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/36576 )
Change subject: mem-cache: Add function to move blocks in the tags
......................................................................
mem-cache: Add function to move blocks in the tags
Add a function to allow moving a block's metadata from a source
entry to an invalid destination entry.
Change-Id: I7c8adbcd1133c907f1eea7f69dca983215bc3960
Signed-off-by: Daniel R. Carvalho <[email protected]>
---
M src/mem/cache/tags/base.cc
M src/mem/cache/tags/base.hh
M src/mem/cache/tags/base_set_assoc.cc
M src/mem/cache/tags/base_set_assoc.hh
M src/mem/cache/tags/fa_lru.cc
M src/mem/cache/tags/fa_lru.hh
M src/mem/cache/tags/sector_tags.cc
M src/mem/cache/tags/sector_tags.hh
8 files changed, 90 insertions(+), 0 deletions(-)
diff --git a/src/mem/cache/tags/base.cc b/src/mem/cache/tags/base.cc
index b00ad49..edd85a4 100644
--- a/src/mem/cache/tags/base.cc
+++ b/src/mem/cache/tags/base.cc
@@ -123,6 +123,19 @@
stats.dataAccesses += 1;
}
+void
+BaseTags::moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk)
+{
+ assert(!dest_blk->isValid());
+ assert(src_blk->isValid());
+
+ // Move src's contents to dest's
+ *dest_blk = std::move(*src_blk);
+
+ assert(dest_blk->isValid());
+ assert(!src_blk->isValid());
+}
+
Addr
BaseTags::extractTag(const Addr addr) const
{
diff --git a/src/mem/cache/tags/base.hh b/src/mem/cache/tags/base.hh
index deda63e..5a407a6 100644
--- a/src/mem/cache/tags/base.hh
+++ b/src/mem/cache/tags/base.hh
@@ -309,6 +309,16 @@
virtual void insertBlock(const PacketPtr pkt, CacheBlk *blk);
/**
+ * Move a block's metadata to another location decided by the
replacement
+ * policy. It behaves as a swap, however, since the destination block
+ * should be invalid, the result is a move.
+ *
+ * @param src_blk The source block.
+ * @param dest_blk The destination block. Must be invalid.
+ */
+ virtual void moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk);
+
+ /**
* Regenerate the block address.
*
* @param block The block.
diff --git a/src/mem/cache/tags/base_set_assoc.cc
b/src/mem/cache/tags/base_set_assoc.cc
index cc2fac6..9f9a261 100644
--- a/src/mem/cache/tags/base_set_assoc.cc
+++ b/src/mem/cache/tags/base_set_assoc.cc
@@ -91,6 +91,18 @@
replacementPolicy->invalidate(blk->replacementData);
}
+void
+BaseSetAssoc::moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk)
+{
+ BaseTags::moveBlock(src_blk, dest_blk);
+
+ // Since the blocks were using different replacement data pointers,
+ // we must touch the replacement data of the new entry, and invalidate
+ // the one that is being moved.
+ replacementPolicy->invalidate(src_blk->replacementData);
+ replacementPolicy->touch(dest_blk->replacementData);
+}
+
BaseSetAssoc *
BaseSetAssocParams::create() const
{
diff --git a/src/mem/cache/tags/base_set_assoc.hh
b/src/mem/cache/tags/base_set_assoc.hh
index 787cc6b..b13b007 100644
--- a/src/mem/cache/tags/base_set_assoc.hh
+++ b/src/mem/cache/tags/base_set_assoc.hh
@@ -199,6 +199,8 @@
replacementPolicy->reset(blk->replacementData);
}
+ void moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk) override;
+
/**
* Limit the allocation for the cache ways.
* @param ways The maximum number of ways available for replacement.
diff --git a/src/mem/cache/tags/fa_lru.cc b/src/mem/cache/tags/fa_lru.cc
index fc69bda..1ded22f 100644
--- a/src/mem/cache/tags/fa_lru.cc
+++ b/src/mem/cache/tags/fa_lru.cc
@@ -226,6 +226,12 @@
}
void
+FALRU::moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk)
+{
+ panic("Moving blocks in FALRU has not been implemented");
+}
+
+void
FALRU::moveToHead(FALRUBlk *blk)
{
// If block is not already head, do the moving
diff --git a/src/mem/cache/tags/fa_lru.hh b/src/mem/cache/tags/fa_lru.hh
index f03ecee..f24ac0e 100644
--- a/src/mem/cache/tags/fa_lru.hh
+++ b/src/mem/cache/tags/fa_lru.hh
@@ -232,6 +232,8 @@
*/
void insertBlock(const PacketPtr pkt, CacheBlk *blk) override;
+ void moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk) override;
+
/**
* Generate the tag from the addres. For fully associative this is
just the
* block address.
diff --git a/src/mem/cache/tags/sector_tags.cc
b/src/mem/cache/tags/sector_tags.cc
index aa6cb24..c249293 100644
--- a/src/mem/cache/tags/sector_tags.cc
+++ b/src/mem/cache/tags/sector_tags.cc
@@ -125,6 +125,7 @@
if (!sector_blk->isValid()) {
// Decrease the number of tags in use
stats.tagsInUse--;
+ assert(stats.tagsInUse.value() >= 0);
// Invalidate replacement data, as we're invalidating the sector
replacementPolicy->invalidate(sector_blk->replacementData);
@@ -183,6 +184,7 @@
} else {
// Increment tag counter
stats.tagsInUse++;
+ assert(stats.tagsInUse.value() <= numSectors);
// A new entry resets the replacement data
replacementPolicy->reset(sector_blk->replacementData);
@@ -192,6 +194,47 @@
BaseTags::insertBlock(pkt, blk);
}
+void
+SectorTags::moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk)
+{
+ const bool dest_was_valid =
+ static_cast<SectorSubBlk*>(dest_blk)->getSectorBlock()->isValid();
+
+ BaseTags::moveBlock(src_blk, dest_blk);
+
+ // Get blocks' sectors. The blocks have effectively been swapped by
now,
+ // so src points to an invalid block, and dest to the moved valid one.
+ SectorSubBlk* src_sub_blk = static_cast<SectorSubBlk*>(src_blk);
+ const SectorBlk* src_sector_blk = src_sub_blk->getSectorBlock();
+ SectorSubBlk* dest_sub_blk = static_cast<SectorSubBlk*>(dest_blk);
+ const SectorBlk* dest_sector_blk = dest_sub_blk->getSectorBlock();
+
+ // Since the blocks were using different replacement data pointers,
+ // we must touch the replacement data of the new entry, and invalidate
+ // the one that is being moved.
+ // When a block in a sector is invalidated, it does not make the tag
+ // invalid automatically, as there might be other blocks in the sector
+ // using it. The tag is invalidated only when there is a single block
+ // in the sector.
+ if (!src_sector_blk->isValid()) {
+ // Invalidate replacement data, as we're invalidating the sector
+ replacementPolicy->invalidate(src_sector_blk->replacementData);
+
+ if (dest_was_valid) {
+ // If destination sector was valid, and the source sector
became
+ // invalid, there is one less tag being used
+ stats.tagsInUse--;
+ assert(stats.tagsInUse.value() >= 0);
+ }
+ } else if (!dest_was_valid) {
+ // If destination sector was invalid and became valid, and the
source
+ // sector is still valid, there is one extra tag being used
+ stats.tagsInUse++;
+ assert(stats.tagsInUse.value() <= numSectors);
+ }
+ replacementPolicy->touch(dest_sector_blk->replacementData);
+}
+
CacheBlk*
SectorTags::findBlock(Addr addr, bool is_secure) const
{
diff --git a/src/mem/cache/tags/sector_tags.hh
b/src/mem/cache/tags/sector_tags.hh
index c56ef24..5c228ee 100644
--- a/src/mem/cache/tags/sector_tags.hh
+++ b/src/mem/cache/tags/sector_tags.hh
@@ -149,6 +149,8 @@
*/
void insertBlock(const PacketPtr pkt, CacheBlk *blk) override;
+ void moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk) override;
+
/**
* Finds the given address in the cache, do not update replacement
data.
* i.e. This is a no-side-effect find of a block.
--
To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/36576
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I7c8adbcd1133c907f1eea7f69dca983215bc3960
Gerrit-Change-Number: 36576
Gerrit-PatchSet: 1
Gerrit-Owner: Daniel Carvalho <[email protected]>
Gerrit-MessageType: newchange
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