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| author | jimharris <jimharris@FreeBSD.org> | 2012-08-22 20:22:55 +0000 |
|---|---|---|
| committer | jimharris <jimharris@FreeBSD.org> | 2012-08-22 20:22:55 +0000 |
| commit | a49bdc9a252d8c144ed4c8d040b34a1e2ce6e653 (patch) | |
| tree | 4d371bc1b95315baf3235a48ed3c94ff639228a5 /sys/sys/pmckern.h | |
| parent | 9d2e20143f198869149c9e2dc114da6153f2df12 (diff) | |
| download | FreeBSD-src-a49bdc9a252d8c144ed4c8d040b34a1e2ce6e653.zip FreeBSD-src-a49bdc9a252d8c144ed4c8d040b34a1e2ce6e653.tar.gz | |
Remove unncessary atomic operation when reading process flags in
PMC_PROC_IS_USING_PMCS macro.
Invocations of this macro are not synchronized with setting/clearing
of P_HWPMC flag, so the atomic operation here isn't needed. Removing
the atomic operation provides noticeable improvement (5-6%) on
some scheduler-intensive workloads with HWPMC_HOOKS enabled on an
8C Sandy Bridge Xeon system.
Sponsored by: Intel
Reviewed by: jhb
MFC after: 1 week
Diffstat (limited to 'sys/sys/pmckern.h')
| -rw-r--r-- | sys/sys/pmckern.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/sys/sys/pmckern.h b/sys/sys/pmckern.h index 44f1916..c623648 100644 --- a/sys/sys/pmckern.h +++ b/sys/sys/pmckern.h @@ -201,8 +201,7 @@ do { \ /* Check if a process is using HWPMCs.*/ #define PMC_PROC_IS_USING_PMCS(p) \ - (__predict_false(atomic_load_acq_int(&(p)->p_flag) & \ - P_HWPMC)) + (__predict_false(p->p_flag & P_HWPMC)) /* Check if a thread have pending user capture. */ #define PMC_IS_PENDING_CALLCHAIN(p) \ |
