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author | Jiri Olsa <jolsa@redhat.com> | 2012-05-23 11:13:02 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2012-05-23 15:40:51 (GMT) |
commit | ab0cce560ef177bdc7a8f73e9962be9d829a7b2c (patch) | |
tree | d9875b21c42862201624eb7d9ea2c36f4ea4035d /kernel/events/core.c | |
parent | 26252ea675663d1bc6747125fcaa2b7cc4ed8a03 (diff) | |
download | linux-fsl-qoriq-ab0cce560ef177bdc7a8f73e9962be9d829a7b2c.tar.xz |
Revert "sched, perf: Use a single callback into the scheduler"
This reverts commit cb04ff9ac424 ("sched, perf: Use a single
callback into the scheduler").
Before this change was introduced, the process switch worked
like this (wrt. to perf event schedule):
schedule (prev, next)
- schedule out all perf events for prev
- switch to next
- schedule in all perf events for current (next)
After the commit, the process switch looks like:
schedule (prev, next)
- schedule out all perf events for prev
- schedule in all perf events for (next)
- switch to next
The problem is, that after we schedule perf events in, the pmu
is enabled and we can receive events even before we make the
switch to next - so "current" still being prev process (event
SAMPLE data are filled based on the value of the "current"
process).
Thats exactly what we see for test__PERF_RECORD test. We receive
SAMPLES with PID of the process that our tracee is scheduled
from.
Discussed with Peter Zijlstra:
> Bah!, yeah I guess reverting is the right thing for now. Sad
> though.
>
> So by having the two hooks we have a black-spot between them
> where we receive no events at all, this black-spot covers the
> hand-over of current and we thus don't receive the 'wrong'
> events.
>
> I rather liked we could do away with both that black-spot and
> clean up the code a little, but apparently people rely on it.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: acme@redhat.com
Cc: paulus@samba.org
Cc: cjashfor@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20120523111302.GC1638@m.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/core.c')
-rw-r--r-- | kernel/events/core.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 91a4459..5b06cbb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2039,8 +2039,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, * accessing the event control register. If a NMI hits, then it will * not restart the event. */ -static void __perf_event_task_sched_out(struct task_struct *task, - struct task_struct *next) +void __perf_event_task_sched_out(struct task_struct *task, + struct task_struct *next) { int ctxn; @@ -2279,8 +2279,8 @@ static void perf_branch_stack_sched_in(struct task_struct *prev, * accessing the event control register. If a NMI hits, then it will * keep the event running. */ -static void __perf_event_task_sched_in(struct task_struct *prev, - struct task_struct *task) +void __perf_event_task_sched_in(struct task_struct *prev, + struct task_struct *task) { struct perf_event_context *ctx; int ctxn; @@ -2305,12 +2305,6 @@ static void __perf_event_task_sched_in(struct task_struct *prev, perf_branch_stack_sched_in(prev, task); } -void __perf_event_task_sched(struct task_struct *prev, struct task_struct *next) -{ - __perf_event_task_sched_out(prev, next); - __perf_event_task_sched_in(prev, next); -} - static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count) { u64 frequency = event->attr.sample_freq; |