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-rw-r--r--src/mem/cache/Cache.py3
-rw-r--r--src/mem/cache/base.cc7
-rw-r--r--src/mem/cache/base.hh6
-rw-r--r--src/mem/cache/tags/Tags.py15
-rw-r--r--src/mem/cache/tags/base.cc6
-rw-r--r--src/mem/cache/tags/base.hh8
-rw-r--r--src/mem/cache/tags/base_set_assoc.hh17
-rw-r--r--src/mem/cache/tags/fa_lru.cc13
-rw-r--r--src/mem/cache/tags/fa_lru.hh1
9 files changed, 59 insertions, 17 deletions
diff --git a/src/mem/cache/Cache.py b/src/mem/cache/Cache.py
index 263b2fea8..dce7e5bf4 100644
--- a/src/mem/cache/Cache.py
+++ b/src/mem/cache/Cache.py
@@ -53,7 +53,8 @@ class BaseCache(MemObject):
size = Param.MemorySize("Capacity")
assoc = Param.Unsigned("Associativity")
- hit_latency = Param.Cycles("Hit latency")
+ tag_latency = Param.Cycles("Tag lookup latency")
+ data_latency = Param.Cycles("Data access latency")
response_latency = Param.Cycles("Latency for the return path on a miss");
max_miss_count = Param.Counter(0,
diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index 814159fc9..7f08d173e 100644
--- a/src/mem/cache/base.cc
+++ b/src/mem/cache/base.cc
@@ -72,9 +72,10 @@ BaseCache::BaseCache(const BaseCacheParams *p, unsigned blk_size)
mshrQueue("MSHRs", p->mshrs, 0, p->demand_mshr_reserve), // see below
writeBuffer("write buffer", p->write_buffers, p->mshrs), // see below
blkSize(blk_size),
- lookupLatency(p->hit_latency),
- forwardLatency(p->hit_latency),
- fillLatency(p->response_latency),
+ lookupLatency(p->tag_latency),
+ dataLatency(p->data_latency),
+ forwardLatency(p->tag_latency),
+ fillLatency(p->data_latency),
responseLatency(p->response_latency),
numTarget(p->tgts_per_mshr),
forwardSnoops(true),
diff --git a/src/mem/cache/base.hh b/src/mem/cache/base.hh
index 716969070..4f7dbb18c 100644
--- a/src/mem/cache/base.hh
+++ b/src/mem/cache/base.hh
@@ -265,6 +265,12 @@ class BaseCache : public MemObject
const Cycles lookupLatency;
/**
+ * The latency of data access of a cache. It occurs when there is
+ * an access to the cache.
+ */
+ const Cycles dataLatency;
+
+ /**
* This is the forward latency of the cache. It occurs when there
* is a cache miss and a request is forwarded downstream, in
* particular an outbound miss.
diff --git a/src/mem/cache/tags/Tags.py b/src/mem/cache/tags/Tags.py
index ab1282ac9..6c0b85044 100644
--- a/src/mem/cache/tags/Tags.py
+++ b/src/mem/cache/tags/Tags.py
@@ -49,17 +49,22 @@ class BaseTags(ClockedObject):
# Get the block size from the parent (system)
block_size = Param.Int(Parent.cache_line_size, "block size in bytes")
- # Get the hit latency from the parent (cache)
- hit_latency = Param.Cycles(Parent.hit_latency,
- "The hit latency for this cache")
+ # Get the tag lookup latency from the parent (cache)
+ tag_latency = Param.Cycles(Parent.tag_latency,
+ "The tag lookup latency for this cache")
+
+ # Get the RAM access latency from the parent (cache)
+ data_latency = Param.Cycles(Parent.data_latency,
+ "The data access latency for this cache")
+
+ sequential_access = Param.Bool(Parent.sequential_access,
+ "Whether to access tags and data sequentially")
class BaseSetAssoc(BaseTags):
type = 'BaseSetAssoc'
abstract = True
cxx_header = "mem/cache/tags/base_set_assoc.hh"
assoc = Param.Int(Parent.assoc, "associativity")
- sequential_access = Param.Bool(Parent.sequential_access,
- "Whether to access tags and data sequentially")
class LRU(BaseSetAssoc):
type = 'LRU'
diff --git a/src/mem/cache/tags/base.cc b/src/mem/cache/tags/base.cc
index 6a926c0d8..cf970c7dd 100644
--- a/src/mem/cache/tags/base.cc
+++ b/src/mem/cache/tags/base.cc
@@ -56,7 +56,11 @@ using namespace std;
BaseTags::BaseTags(const Params *p)
: ClockedObject(p), blkSize(p->block_size), size(p->size),
- accessLatency(p->hit_latency), cache(nullptr), warmupBound(0),
+ lookupLatency(p->tag_latency),
+ accessLatency(p->sequential_access ?
+ p->tag_latency + p->data_latency :
+ std::max(p->tag_latency, p->data_latency)),
+ cache(nullptr), warmupBound(0),
warmedUp(false), numBlocks(0)
{
}
diff --git a/src/mem/cache/tags/base.hh b/src/mem/cache/tags/base.hh
index f1ef947a5..8c68cc093 100644
--- a/src/mem/cache/tags/base.hh
+++ b/src/mem/cache/tags/base.hh
@@ -69,7 +69,13 @@ class BaseTags : public ClockedObject
const unsigned blkSize;
/** The size of the cache. */
const unsigned size;
- /** The access latency of the cache. */
+ /** The tag lookup latency of the cache. */
+ const Cycles lookupLatency;
+ /**
+ * The total access latency of the cache. This latency
+ * is different depending on the cache access mode
+ * (parallel or sequential)
+ */
const Cycles accessLatency;
/** Pointer to the parent cache. */
BaseCache *cache;
diff --git a/src/mem/cache/tags/base_set_assoc.hh b/src/mem/cache/tags/base_set_assoc.hh
index 31284991f..a6dcf0572 100644
--- a/src/mem/cache/tags/base_set_assoc.hh
+++ b/src/mem/cache/tags/base_set_assoc.hh
@@ -208,7 +208,6 @@ public:
Addr tag = extractTag(addr);
int set = extractSet(addr);
BlkType *blk = sets[set].findBlk(tag, is_secure);
- lat = accessLatency;;
// Access all tags in parallel, hence one in each way. The data side
// either accesses all blocks in parallel, or one block sequentially on
@@ -223,12 +222,20 @@ public:
}
if (blk != nullptr) {
- if (blk->whenReady > curTick()
- && cache->ticksToCycles(blk->whenReady - curTick())
- > accessLatency) {
- lat = cache->ticksToCycles(blk->whenReady - curTick());
+ // If a cache hit
+ lat = accessLatency;
+ // Check if the block to be accessed is available. If not,
+ // apply the accessLatency on top of block->whenReady.
+ if (blk->whenReady > curTick() &&
+ cache->ticksToCycles(blk->whenReady - curTick()) >
+ accessLatency) {
+ lat = cache->ticksToCycles(blk->whenReady - curTick()) +
+ accessLatency;
}
blk->refCount += 1;
+ } else {
+ // If a cache miss
+ lat = lookupLatency;
}
return blk;
diff --git a/src/mem/cache/tags/fa_lru.cc b/src/mem/cache/tags/fa_lru.cc
index 0d6a3392d..cdd0db216 100644
--- a/src/mem/cache/tags/fa_lru.cc
+++ b/src/mem/cache/tags/fa_lru.cc
@@ -186,6 +186,16 @@ FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, int context_src,
FALRUBlk* blk = hashLookup(blkAddr);
if (blk && blk->isValid()) {
+ // If a cache hit
+ lat = accessLatency;
+ // Check if the block to be accessed is available. If not,
+ // apply the accessLatency on top of block->whenReady.
+ if (blk->whenReady > curTick() &&
+ cache->ticksToCycles(blk->whenReady - curTick()) >
+ accessLatency) {
+ lat = cache->ticksToCycles(blk->whenReady - curTick()) +
+ accessLatency;
+ }
assert(blk->tag == blkAddr);
tmp_in_cache = blk->inCache;
for (unsigned i = 0; i < numCaches; i++) {
@@ -200,6 +210,8 @@ FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, int context_src,
moveToHead(blk);
}
} else {
+ // If a cache miss
+ lat = lookupLatency;
blk = nullptr;
for (unsigned i = 0; i <= numCaches; ++i) {
misses[i]++;
@@ -209,7 +221,6 @@ FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, int context_src,
*inCache = tmp_in_cache;
}
- lat = accessLatency;
//assert(check());
return blk;
}
diff --git a/src/mem/cache/tags/fa_lru.hh b/src/mem/cache/tags/fa_lru.hh
index 1bbd9fbfb..710dfafbf 100644
--- a/src/mem/cache/tags/fa_lru.hh
+++ b/src/mem/cache/tags/fa_lru.hh
@@ -51,6 +51,7 @@
#include <list>
#include <unordered_map>
+#include "mem/cache/base.hh"
#include "mem/cache/blk.hh"
#include "mem/cache/tags/base.hh"
#include "mem/packet.hh"
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 01:08:59 +0000