Matt Sinclair has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/51368 )
Change subject: mem-ruby: Move VIPER TCC decrements to action from in_port
......................................................................
mem-ruby: Move VIPER TCC decrements to action from in_port
Currently, the GPU VIPER TCC protocol handles races between atomics in
the triggerQueue_in. This in_port does not check for resource
availability, which can cause the trigger queue to execute multiple
times. Although this is the expected behavior, the code for handling
atomic races decrements the atomicDoneCnt flag in the trigger queue,
which is not safe since resource contention may cause it to execute
multiple times.
To resolve this issue, this commit moves the decrementing of this
counter to a new action that is called in an event that happens only
when the race between atomics is detected.
Change-Id: I552fd4f34fdd9ebeec99fb7aeb4eeb7b150f577f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51368
Reviewed-by: Jason Lowe-Power <[email protected]>
Reviewed-by: Matthew Poremba <[email protected]>
Maintainer: Jason Lowe-Power <[email protected]>
Tested-by: kokoro <[email protected]>
---
M src/mem/ruby/protocol/GPU_VIPER-TCC.sm
1 file changed, 31 insertions(+), 1 deletion(-)
Approvals:
Jason Lowe-Power: Looks good to me, but someone else must approve; Looks
good to me, approved
Matthew Poremba: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/mem/ruby/protocol/GPU_VIPER-TCC.sm
b/src/mem/ruby/protocol/GPU_VIPER-TCC.sm
index 6112f38..571587f 100644
--- a/src/mem/ruby/protocol/GPU_VIPER-TCC.sm
+++ b/src/mem/ruby/protocol/GPU_VIPER-TCC.sm
@@ -268,7 +268,6 @@
if (tbe.numAtomics == 0 && tbe.atomicDoneCnt == 1) {
trigger(Event:AtomicDone, in_msg.addr, cache_entry, tbe);
} else {
- tbe.atomicDoneCnt := tbe.atomicDoneCnt - 1;
trigger(Event:AtomicNotDone, in_msg.addr, cache_entry, tbe);
}
}
@@ -599,6 +598,10 @@
}
}
+ action(dadc_decrementAtomicDoneCnt, "dadc", desc="decrement atomics done
cnt flag") {
+ tbe.atomicDoneCnt := tbe.atomicDoneCnt - 1;
+ }
+
action(ptr_popTriggerQueue, "ptr", desc="pop Trigger") {
triggerQueue_in.dequeue(clockEdge());
}
@@ -787,6 +790,7 @@
}
transition(A, AtomicNotDone) {TagArrayRead} {
+ dadc_decrementAtomicDoneCnt;
ptr_popTriggerQueue;
}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I552fd4f34fdd9ebeec99fb7aeb4eeb7b150f577f
Gerrit-Change-Number: 51368
Gerrit-PatchSet: 3
Gerrit-Owner: Matt Sinclair <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Matt Sinclair <[email protected]>
Gerrit-Reviewer: Matthew Poremba <[email protected]>
Gerrit-Reviewer: kokoro <[email protected]>
Gerrit-CC: Kyle Roarty <[email protected]>
Gerrit-MessageType: merged
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