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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-06-22 16:35:24 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-06-25 21:39:06 +0200 |
commit | 194002b274e9169a04beb1b23dcc132159bb566c (patch) | |
tree | 6977e48df4a1429dae999d4afe23e5e28febc99e /kernel/perf_counter.c | |
parent | 7f8b4e4e0988dadfd22330fd147ad2453e19f510 (diff) | |
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perf_counter, x86: Add mmap counter read support
Update the mmap control page with the needed information to
use the userspace RDPMC instruction for self monitoring.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
-rw-r--r-- | kernel/perf_counter.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 23614ad..02994a7 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1753,6 +1753,14 @@ int perf_counter_task_disable(void) return 0; } +static int perf_counter_index(struct perf_counter *counter) +{ + if (counter->state != PERF_COUNTER_STATE_ACTIVE) + return 0; + + return counter->hw.idx + 1 - PERF_COUNTER_INDEX_OFFSET; +} + /* * Callers need to ensure there can be no nesting of this function, otherwise * the seqlock logic goes bad. We can not serialize this because the arch @@ -1777,7 +1785,7 @@ void perf_counter_update_userpage(struct perf_counter *counter) preempt_disable(); ++userpg->lock; barrier(); - userpg->index = counter->hw.idx; + userpg->index = perf_counter_index(counter); userpg->offset = atomic64_read(&counter->count); if (counter->state == PERF_COUNTER_STATE_ACTIVE) userpg->offset -= atomic64_read(&counter->hw.prev_count); |