diff options
| author | Faissal Sleiman <sleimanf@umich.edu> | 2014-04-19 09:00:30 -0500 |
|---|---|---|
| committer | Faissal Sleiman <sleimanf@umich.edu> | 2014-04-19 09:00:30 -0500 |
| commit | a1570f544f7eb24d87a664038705ae6801862eab (patch) | |
| tree | 653b636176ab47b13c6b4f87f21f457363f62c3e /src/cpu/o3/commit_impl.hh | |
| parent | d9fa950396e8f331bbfb1023348c8c680967b1be (diff) | |
| download | gem5-a1570f544f7eb24d87a664038705ae6801862eab.tar.xz | |
o3: Fix occupancy checks for SMT
A number of calls to isEmpty() and numFreeEntries()
should be thread-specific.
In cpu.cc, the fact that tid is /*commented*/ out is a bug. Say the rob
has instructions from thread 0 (isEmpty() returns false), and none from
thread 1. If we are trying to squash all of thread 1, then
readTailInst(thread 1) will be called because rob->isEmpty() returns
false. The result is end_it is not in the list and the while
statement loops indefinitely back over the cpu's instList.
In iew_impl.hh, all threads are told they have the entire remaining IQ, when
each thread actually has a certain allocation. The result is extra stalls at
the iew dispatch stage which the rename stage usually takes care of.
In commit_impl.hh, rob->readHeadInst(thread 1) can be called if the rob only
contains instructions from thread 0. This returns a dummyInst (which may work
since we are trying to squash all instructions, but hardly seems like the right
way to do it).
In rob_impl.hh this fix skips the rest of the function more frequently and is
more efficient.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Diffstat (limited to 'src/cpu/o3/commit_impl.hh')
| -rw-r--r-- | src/cpu/o3/commit_impl.hh | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/cpu/o3/commit_impl.hh b/src/cpu/o3/commit_impl.hh index 91e8e7681..5ca15f611 100644 --- a/src/cpu/o3/commit_impl.hh +++ b/src/cpu/o3/commit_impl.hh @@ -561,7 +561,7 @@ DefaultCommit<Impl>::squashAll(ThreadID tid) // then use one older sequence number. // Hopefully this doesn't mess things up. Basically I want to squash // all instructions of this thread. - InstSeqNum squashed_inst = rob->isEmpty() ? + InstSeqNum squashed_inst = rob->isEmpty(tid) ? lastCommitedSeqNum[tid] : rob->readHeadInst(tid)->seqNum - 1; // All younger instructions will be squashed. Set the sequence |