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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-22 16:35:24 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-25 21:39:06 +0200
commit194002b274e9169a04beb1b23dcc132159bb566c (patch)
tree6977e48df4a1429dae999d4afe23e5e28febc99e /kernel/perf_counter.c
parent7f8b4e4e0988dadfd22330fd147ad2453e19f510 (diff)
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.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 23614adab47..02994a719e2 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);