Commit-ID: e758a33d6fc5b9d6a3ae489863d04fcecad8120b
Gitweb: http://git.kernel.org/tip/e758a33d6fc5b9d6a3ae489863d04fcecad8120b
Author: Paul Mackerras <paulus@xxxxxxxxx>
AuthorDate: Tue, 12 May 2009 21:59:01 +1000
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 12 May 2009 15:31:06 +0200
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@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <18953.25733.53359.147452@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
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) {
/*
--
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