Re: [PATCH v3 00/12] perf, persistent: Add persistent events

From: Jean Pihet
Date: Fri Mar 28 2014 - 10:54:21 EST


Hi,

Now that the feature is resurfacing, I would like to take over the
task for persistent events.
What is the status of the series, is it close to acceptance?

AFAICS the patch RFC 12/12 was under discussion, mainly about the
naming of the ioctls (latest e-mail is in favor of CLAIM/UNCLAIM).

Any thoughts?

Let me rebase the code against the latest mainline and re-start the discussion.

Thread: https://lkml.org/lkml/2013/8/22/306
RFC 12/12: https://lkml.org/lkml/2013/8/27/264

Regards,
Jean

On 27 August 2013 14:38, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Tue, Aug 27, 2013 at 02:27:21PM +0200, Robert Richter wrote:
>> > > There are ioctl functions to control persistent events that can be
>> > > used to detach or attach an event to or from a process. The
>> > > PERF_EVENT_IOC_DETACH ioctl call makes an event persistent.
>> >
>> > Yeah, we probably want to abstract this a step further by allowing
>> > to attach/detach fds to/from events. Then "persistent" is only one
>> > incarnation of us always detaching from the event during its lifetime.
>> >
>> > If we close an event while it is attached, it gets destroyed - i.e.,
>> > current functionality, etc. See the other thread.
>>
>> I don't know what you mean here exactly, please explain.
>
> Basically that detaching an event shouldn't make it persistent
> explicitly - it simply continues running in the background. When we
> reattach to it and die with the event attached, then it gets destroyed
> too.
>
> Which means, we can have arbitrary life periods of events, persistency
> being only a special case of it.
>
> IOW, as long as an event is detached in the background, it counts.
> When something attaches to it and that something exits, the event gets
> destroyed too, as part of the process teardown.
>
> And this is probably the most generic way to look at it.
>
> --
> Regards/Gruss,
> Boris.
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