Re: [PATCH V4 04/23] perf/x86/intel: Support adaptive PEBSv4

Andi Kleen
2019-03-27T14:42:40Z

> We need to call perf_event_overflow() for the last record of each event.
> It's hard to detect which record is the last record of the event with one
> pass walking.
>
> Also, I'm not sure how much we can save with one pass walking. The
> optimization should only benefit large PEBS. The total number of records for
> large PEBS should not be huge.
> I will evaluate the performance impact of one pass walking. If there is
> observed performance improvement, I will submit a separate patch later.
>
> For now, I think we can still use the mature two pass walking method.

Okay sounds reasonable to keep it then.

Thanks,

-Andi