Re: [PATCH v4 00/16] perf, persistent: Add persistent events

Borislav Petkov
2014-05-09T10:17:27Z

On Wed, May 07, 2014 at 07:01:55PM +0200, Robert Richter wrote:
> I am fine with a fixed size. But this design might not be changable in
> the future without breaking the API. So its worth to think about this.
> Maybe we allow the process also to create the buffer, there are 2
> variants then:
>
> perf_event_open(...);
> mmap(..., fd, ...);
> ioctl(fd, set_persistent, 1); /* Use existing buffer. */
> close();
>
> fd = perf_event_open(...);
> ioctl(fd, set_persistent, 1); /* Create buffer with default size. */
> close();
>
> This would solve the problem how we adjust buffer size.
>
> This requires a way to detect buffer size. See my mail how this could
> be done.

Yep, this makes sense and fits nicely with the perf interface so
persistent buffer sizes will be established at event creation.

This is all fine then.

--
Regards/Gruss,
Boris.

Sent from a fat crate under my desk. Formatting is fine.
--