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author | Paul Mackerras <paulus@samba.org> | 2009-05-12 21:59:01 +1000 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-05-12 15:31:06 +0200 |
commit | e758a33d6fc5b9d6a3ae489863d04fcecad8120b (patch) | |
tree | 3345d35fd5c9ee41a2f5a22fc5795672c0db7c2b /kernel/perf_counter.c | |
parent | 615a3f1e055ac9b0ae74e1f935a12ea2cfe2a2ad (diff) | |
download | op-kernel-dev-e758a33d6fc5b9d6a3ae489863d04fcecad8120b.zip op-kernel-dev-e758a33d6fc5b9d6a3ae489863d04fcecad8120b.tar.gz |
perf_counter: call hw_perf_save_disable/restore around group_sched_in
I noticed that when enabling a group via the PERF_COUNTER_IOC_ENABLE
ioctl on the group leader, the counters weren't enabled and counting
immediately on return from the ioctl, but did start counting a little
while later (presumably after a context switch).
The reason was that __perf_counter_enable calls group_sched_in which
calls hw_perf_group_sched_in, which on powerpc assumes that the caller
has called hw_perf_save_disable already. Until commit 46d686c6
("perf_counter: put whole group on when enabling group leader") it was
true that all callers of group_sched_in had called
hw_perf_save_disable first, and the powerpc hw_perf_group_sched_in
relies on that (there isn't an x86 version).
This fixes the problem by putting calls to hw_perf_save_disable /
hw_perf_restore around the calls to group_sched_in and
counter_sched_in in __perf_counter_enable. Having the calls to
hw_perf_save_disable/restore around the counter_sched_in call is
harmless and makes this call consistent with the other call sites
of counter_sched_in, which have all called hw_perf_save_disable first.
[ Impact: more precise counter group disable/enable functionality ]
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <18953.25733.53359.147452@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
-rw-r--r-- | kernel/perf_counter.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 5ea0240..ff166c1 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -663,6 +663,7 @@ static void __perf_counter_enable(void *info) struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter_context *ctx = counter->ctx; struct perf_counter *leader = counter->group_leader; + unsigned long pmuflags; unsigned long flags; int err; @@ -689,14 +690,18 @@ static void __perf_counter_enable(void *info) if (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE) goto unlock; - if (!group_can_go_on(counter, cpuctx, 1)) + if (!group_can_go_on(counter, cpuctx, 1)) { err = -EEXIST; - else if (counter == leader) - err = group_sched_in(counter, cpuctx, ctx, - smp_processor_id()); - else - err = counter_sched_in(counter, cpuctx, ctx, - smp_processor_id()); + } else { + pmuflags = hw_perf_save_disable(); + if (counter == leader) + err = group_sched_in(counter, cpuctx, ctx, + smp_processor_id()); + else + err = counter_sched_in(counter, cpuctx, ctx, + smp_processor_id()); + hw_perf_restore(pmuflags); + } if (err) { /* |