Messages in this thread | | | Date | Tue, 23 Feb 2016 16:48:49 +0100 | From | Jiri Olsa <> | Subject | Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec |
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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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