Commit-ID: 4defea8559bc0f97a899d94c8d19d3b8bb802bc4
Gitweb: http://git.kernel.org/tip/4defea8559bc0f97a899d94c8d19d3b8bb802bc4
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Thu, 10 Nov 2011 15:15:42 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 6 Dec 2011 08:33:58 +0100
perf, x86: Prefer fixed-purpose counters when scheduling
This avoids a scheduling failure for cases like:
cycles, cycles, instructions, instructions (on Core2)
Which would end up being programmed like:
PMC0, PMC1, FP-instructions, fail
Because all events will have the same weight.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-8tnwb92asqj7xajqqoty4gel@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/kernel/cpu/perf_event.c | 19 ++++++++++++++-----
1 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index fa6fdec..66f8ba9 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -574,16 +574,25 @@ static bool __perf_sched_find_counter(struct perf_sched *sched)
c = sched->constraints[sched->state.event];
+ /* Prefer fixed purpose counters */
+ if (x86_pmu.num_counters_fixed) {
+ idx = X86_PMC_IDX_FIXED;
+ for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_MAX) {
+ if (!__test_and_set_bit(idx, sched->state.used))
+ goto done;
+ }
+ }
/* Grab the first unused counter starting with idx */
idx = sched->state.counter;
- for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_MAX) {
+ for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_FIXED) {
if (!__test_and_set_bit(idx, sched->state.used))
- break;
+ goto done;
}
- sched->state.counter = idx;
- if (idx >= X86_PMC_IDX_MAX)
- return false;
+ return false;
+
+done:
+ sched->state.counter = idx;
if (c->overlap)
perf_sched_save_state(sched);
--
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