[BUG] perf: perf_output_sample() merge issue?

[BUG] perf: perf_output_sample() merge issue?

[Stephane Eranian]

Peter,

I was looking at perf_output_sample() today, when I ran
into the following weird statement coming from:

commit a7ac67ea021b4603095d2aa458bc41641238f22c
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date:   Mon Jun 27 16:47:16 2011 +0200

    perf: Remove the perf_output_begin(.sample) argument

    Since only samples call perf_output_sample() its much saner (and more


I think the intent of this commit was to add the watermark check
at the very end of the perf_output_sample() and NOT between processing
of RAW and BRANCH_STACK. Something may have gone wrong
in the merge.

Can you confirm this?


perf_output_sample()
{
        if (sample_type & PERF_SAMPLE_RAW) {
        }

        if (!event->attr.watermark) {
                int wakeup_events = event->attr.wakeup_events;

                if (wakeup_events) {
                        struct ring_buffer *rb = handle->rb;
                        int events = local_inc_return(&rb->events);

                        if (events >= wakeup_events) {
                                local_sub(wakeup_events, &rb->events);
                                local_inc(&rb->wakeup);
                        }
                }
        }

        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
        }
}

Re: [BUG] perf: perf_output_sample() merge issue?

[Peter Zijlstra]

On Wed, 2012-06-13 at 14:51 +0200, Stephane Eranian wrote:
> I think the intent of this commit was to add the watermark check
> at the very end of the perf_output_sample() and NOT between processing
> of RAW and BRANCH_STACK. Something may have gone wrong
> in the merge.
> 
> Can you confirm this? 

Yes very much so, good spotting. Weird stuff this merging.

Re: [BUG] perf: perf_output_sample() merge issue?

[Stephane Eranian]

On Wed, Jun 13, 2012 at 3:04 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2012-06-13 at 14:51 +0200, Stephane Eranian wrote:
>> I think the intent of this commit was to add the watermark check
>> at the very end of the perf_output_sample() and NOT between processing
>> of RAW and BRANCH_STACK. Something may have gone wrong
>> in the merge.
>>
>> Can you confirm this?
>
> Yes very much so, good spotting. Weird stuff this merging.

Ok, so I will post a patch to fix that then.