Messages in this thread |  | | | Subject | Re: [GIT PULL] perf crash fix | | From | Peter Zijlstra <> | | Date | Thu, 03 Jun 2010 11:08:04 +0200 |
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On Thu, 2010-06-03 at 10:02 +0200, Peter Zijlstra wrote: > On Thu, 2010-06-03 at 05:13 +0200, Frederic Weisbecker wrote: > > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > > index 858f56f..b666d7d 100644 > > --- a/kernel/perf_event.c > > +++ b/kernel/perf_event.c > > @@ -1510,20 +1510,16 @@ do { \ > > return div64_u64(dividend, divisor); > > } > > > > -static void perf_event_stop(struct perf_event *event) > > +static void perf_event_stop_hwevent(struct perf_event *event) > > { > > - if (!event->pmu->stop) > > - return event->pmu->disable(event); > > - > > - return event->pmu->stop(event); > > + if (event->pmu->stop && !is_software_event(event)) > > + return event->pmu->stop(event); > > } > > > > -static int perf_event_start(struct perf_event *event) > > +static int perf_event_start_hwevent(struct perf_event *event) > > { > > - if (!event->pmu->start) > > - return event->pmu->enable(event); > > - > > - return event->pmu->start(event); > > + if (event->pmu->start && !is_software_event(event)) > > + return event->pmu->start(event); > > } > > > > static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) > > @@ -1546,9 +1542,9 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) > > > > if (atomic64_read(&hwc->period_left) > 8*sample_period) { > > perf_disable(); > > - perf_event_stop(event); > > + perf_event_stop_hwevent(event); > > atomic64_set(&hwc->period_left, 0); > > - perf_event_start(event); > > + perf_event_start_hwevent(event); > > perf_enable(); > > } > > }
Your patch actually breaks some hardware pmu implementations.
> Urhm,. isn't is much easier to simply give the software events a NOP > stop/start callback? > > kernel/perf_event.c | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > index 858f56f..16c99e1 100644 > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -4276,9 +4276,15 @@ static void perf_swevent_disable(struct perf_event *event) > hlist_del_rcu(&event->hlist_entry); > } > > +static void perf_swevent_nop(struct perf_event *event) > +{ > +} > + > static const struct pmu perf_ops_generic = { > .enable = perf_swevent_enable, > .disable = perf_swevent_disable, > + .start = perf_swevent_nop, > + .stop = perf_swevent_nop, > .read = perf_swevent_read, > .unthrottle = perf_swevent_unthrottle, > }; >
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