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Groups > linux.kernel > #1340803
| From | Jiri Olsa <jolsa@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec |
| Date | 2016-02-23 16:50 +0100 |
| Message-ID | <r5nnP-7qp-13@gated-at.bofh.it> (permalink) |
| References | <r3UHf-6xJ-3@gated-at.bofh.it> <r3UHg-6xJ-17@gated-at.bofh.it> <r5n4v-7ic-29@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Feb 23, 2016 at 04:27:29PM +0100, Peter Zijlstra wrote:
> On Fri, Feb 19, 2016 at 03:37:47PM +0100, Peter Zijlstra wrote:
> > Oleg reported that enable_on_exec results in weird scale factors.
> >
> > The recent commit 3e349507d12d ("perf: Fix perf_enable_on_exec() event
> > scheduling") caused this by moving task_ctx_sched_out() from before
> > __perf_event_mask_enable() to after it.
> >
> > The overlooked concequence of that change is that task_ctx_sched_out()
> > would update the ctx time fields, and now __perf_event_mask_enable()
> > uses stale time.
> >
> > Fix this by adding an explicit time update.
> >
> > While looking at this, I also found that we need an ctx->is_active
> > check in perf_install_in_context().
> >
> > XXX: does this actually fix the reported issue? I'm not sure what the
> > reproduction case is. Also an earlier version made Jiri's machine
> > explode -- something I've not managed to reproduce either.
>
> Jiri, can you have a look at this and perhaps share the reproducer?
yep, I'm testing this patchset, but got stuck with 'crash' tool to get
some reasonable output.. got stuck on unrelated sched deadlock ;-)
the reproducer is described in this email:
http://marc.info/?l=linux-kernel&m=145568006709552&w=2
CC-ing Pratyush
jjirka
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Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Peter Zijlstra <peterz@infradead.org> - 2016-02-23 16:30 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Jiri Olsa <jolsa@redhat.com> - 2016-02-23 16:50 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Pratyush Anand <panand@redhat.com> - 2016-02-23 17:40 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Peter Zijlstra <peterz@infradead.org> - 2016-02-23 18:50 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Peter Zijlstra <peterz@infradead.org> - 2016-02-24 13:00 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Peter Zijlstra <peterz@infradead.org> - 2016-02-24 15:10 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Peter Zijlstra <peterz@infradead.org> - 2016-02-24 17:10 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Pratyush Anand <panand@redhat.com> - 2016-02-25 05:10 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Jiri Olsa <jolsa@redhat.com> - 2016-02-23 22:50 +0100
Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec Oleg Nesterov <oleg@redhat.com> - 2016-02-26 03:30 +0100
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