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authorDaniel R. Carvalho <odanrc@yahoo.com.br>2018-11-28 13:54:42 +0100
committerDaniel Carvalho <odanrc@yahoo.com.br>2018-12-04 10:34:26 +0000
commit174da8e2da6a896d2e97bc264f9c827a0f4c35ac (patch)
treeb362adf7f2abf0cf309bf421ba0240c164791932 /src/mem/cache
parentfc09f4a24e22988cb89650b1d5b1f3716cf5c893 (diff)
downloadgem5-174da8e2da6a896d2e97bc264f9c827a0f4c35ac.tar.xz
mem-cache: Add getter and setter to CacheBlk::whenReady
Add a getter and a setter function to access CacheBlk::whenReady to encapsulate the variable and allow error checking. This error checking consists on verifying that writes to a block after it has been inserted follow a chronological order. As a side effect, tickInserted retain its value until updated, that is, it is not reset in invalidate(). Change-Id: Idc3c5a99c3f002ee9acc2424f00e554877fd3a69 Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br> Reviewed-on: https://gem5-review.googlesource.com/c/14715 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Diffstat (limited to 'src/mem/cache')
-rw-r--r--src/mem/cache/base.cc20
-rw-r--r--src/mem/cache/cache_blk.hh37
2 files changed, 43 insertions, 14 deletions
diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index 244d7ce4e..bad24f7ee 100644
--- a/src/mem/cache/base.cc
+++ b/src/mem/cache/base.cc
@@ -900,10 +900,11 @@ BaseCache::calculateAccessLatency(const CacheBlk* blk,
}
// Check if the block to be accessed is available. If not, apply the
- // access latency on top of block->whenReady.
- if (blk->whenReady > curTick() &&
- ticksToCycles(blk->whenReady - curTick()) > lat) {
- lat += ticksToCycles(blk->whenReady - curTick());
+ // access latency on top of when the block is ready to be accessed.
+ const Tick when_ready = blk->getWhenReady();
+ if (when_ready > curTick() &&
+ ticksToCycles(when_ready - curTick()) > lat) {
+ lat += ticksToCycles(when_ready - curTick());
}
}
@@ -1024,8 +1025,8 @@ BaseCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
incHitCount(pkt);
// populate the time when the block will be ready to access.
- blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
- pkt->payloadDelay;
+ blk->setWhenReady(clockEdge(fillLatency) + pkt->headerDelay +
+ pkt->payloadDelay);
return true;
} else if (pkt->cmd == MemCmd::CleanEvict) {
if (blk) {
@@ -1081,8 +1082,8 @@ BaseCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
incHitCount(pkt);
// populate the time when the block will be ready to access.
- blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
- pkt->payloadDelay;
+ blk->setWhenReady(clockEdge(fillLatency) + pkt->headerDelay +
+ pkt->payloadDelay);
// if this a write-through packet it will be sent to cache
// below
return !pkt->writeThrough();
@@ -1212,8 +1213,7 @@ BaseCache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
pkt->writeDataToBlock(blk->data, blkSize);
}
// We pay for fillLatency here.
- blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
- pkt->payloadDelay;
+ blk->setWhenReady(clockEdge(fillLatency) + pkt->payloadDelay);
return blk;
}
diff --git a/src/mem/cache/cache_blk.hh b/src/mem/cache/cache_blk.hh
index d7530d656..9ace496ce 100644
--- a/src/mem/cache/cache_blk.hh
+++ b/src/mem/cache/cache_blk.hh
@@ -105,7 +105,10 @@ class CacheBlk : public ReplaceableEntry
/** The current status of this block. @sa CacheBlockStatusBits */
State status;
- /** Which curTick() will this block be accessible */
+ /**
+ * Which curTick() will this block be accessible. Its value is only
+ * meaningful if the block is valid.
+ */
Tick whenReady;
/** Number of references to this block since it was brought in. */
@@ -114,7 +117,10 @@ class CacheBlk : public ReplaceableEntry
/** holds the source requestor ID for this block. */
int srcMasterId;
- /** Tick on which the block was inserted in the cache. */
+ /**
+ * Tick on which the block was inserted in the cache. Its value is only
+ * meaningful if the block is valid.
+ */
Tick tickInserted;
protected:
@@ -160,7 +166,7 @@ class CacheBlk : public ReplaceableEntry
std::list<Lock> lockList;
public:
- CacheBlk() : data(nullptr)
+ CacheBlk() : data(nullptr), tickInserted(0)
{
invalidate();
}
@@ -211,7 +217,6 @@ class CacheBlk : public ReplaceableEntry
whenReady = MaxTick;
refCount = 0;
srcMasterId = Request::invldMasterId;
- tickInserted = MaxTick;
lockList.clear();
}
@@ -261,6 +266,30 @@ class CacheBlk : public ReplaceableEntry
}
/**
+ * Get tick at which block's data will be available for access.
+ *
+ * @return Data ready tick.
+ */
+ Tick getWhenReady() const
+ {
+ return whenReady;
+ }
+
+ /**
+ * Set tick at which block's data will be available for access. The new
+ * tick must be chronologically sequential with respect to previous
+ * accesses.
+ *
+ * @param tick New data ready tick.
+ */
+ void setWhenReady(const Tick tick)
+ {
+ assert((whenReady == MaxTick) || (tick >= whenReady));
+ assert(tick >= tickInserted);
+ whenReady = tick;
+ }
+
+ /**
* Set member variables when a block insertion occurs. Resets reference
* count to 1 (the insertion counts as a reference), and touch block if
* it hadn't been touched previously. Sets the insertion tick to the