Messages in this thread | | | Date | Thu, 30 Oct 2014 11:31:00 -0200 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v5 18/20] perf: Allocate ring buffers for inherited per-task kernel events |
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Em Thu, Oct 30, 2014 at 09:43:59AM +0100, Peter Zijlstra escreveu: > On Fri, Oct 24, 2014 at 10:44:54AM +0300, Alexander Shishkin wrote: > > Peter Zijlstra <peterz@infradead.org> writes: > > > On Mon, Oct 13, 2014 at 04:45:46PM +0300, Alexander Shishkin wrote: > > >> When a new event is inherited from a per-task kernel event that has a > > >> ring buffer, allocate a new buffer for this event so that data from the > > >> child task is collected and can later be retrieved for sample annotation > > >> or core dump inclusion. This ring buffer is released when the event is > > >> freed, for example, when the child task exits.
> > > This causes a pinned memory explosion, not at all nice that.
> > > I think I see why and all, but it would be ever so good to not have to > > > allocate so much memory.
> > Are there any controls we could use to limit such memory usage?
> I'd say the same limit we're already accounting the mmap()s against. But > the question is; what do we do when we run out?
> Will we fail clone()? That might 'surprise' quite a few people, that
> their application won't work when profiled.
Can't we just emit PERF_RECORD_THROTTLE or similar stuff then? I.e. somehow mark the cloned process as not being profiled due to ENOMEM?
- Arnaldo
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