From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755959Ab1C3Ovy (ORCPT ); Wed, 30 Mar 2011 10:51:54 -0400 Received: from casper.infradead.org ([85.118.1.10]:40059 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755269Ab1C3Ovx convert rfc822-to-8bit (ORCPT ); Wed, 30 Mar 2011 10:51:53 -0400 Subject: Re: [PATCH,RFC] perf: panic due to inclied cpu context task_ctx value From: Peter Zijlstra To: Jiri Olsa Cc: Oleg Nesterov , Paul Mackerras , Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: <20110330130951.GA2124@jolsa.brq.redhat.com> References: <1301153868.2250.359.camel@laptop> <20110326161346.GA18272@redhat.com> <1301157483.2250.366.camel@laptop> <20110326170922.GA20329@redhat.com> <20110326173545.GA22919@redhat.com> <1301164168.2250.370.camel@laptop> <20110328133033.GA8254@redhat.com> <1301324275.4859.25.camel@twins> <1301327368.4859.28.camel@twins> <20110328165648.GA9304@redhat.com> <20110330130951.GA2124@jolsa.brq.redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 30 Mar 2011 16:51:24 +0200 Message-ID: <1301496684.4859.192.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-03-30 at 15:09 +0200, Jiri Olsa wrote: > > > +#ifdef HAVE_JUMP_LABEL > +static inline > +void perf_sched_events_inc(void) > +{ > + jump_label_inc(&perf_sched_events_out); > + smp_mb__after_atomic_inc(); > + jump_label_inc(&perf_sched_events_in); > +} > + > +static inline > +void perf_sched_events_dec(void) > +{ > + if (atomic_dec_and_test(&perf_sched_events_in)) { > + jump_label_disable(&perf_sched_events_in); > + synchronize_sched(); > + } > + > + jump_label_dec(&perf_sched_events_out); > +} > +#else > +static inline > +void perf_sched_events_inc(void) > +{ > + atomic_inc(&perf_sched_events_out); > + smp_mb__after_atomic_inc(); > + atomic_inc(&perf_sched_events_in); > +} > + > +static inline > +void perf_sched_events_dec(void) > +{ > + if (atomic_dec_and_test(&perf_sched_events_in)) > + synchronize_sched(); > + atomic_dec(&perf_sched_events_out); > +} > +#endif /* HAVE_JUMP_LABEL */ I wrote a similar patch which is slightly smaller: --- Subject: perf: Delay disabling the perf_event_task_sched_out() hook From: Peter Zijlstra Date: Wed Mar 30 13:47:09 CEST 2011 Suggested-by: Oleg Nesterov Signed-off-by: Peter Zijlstra --- include/linux/perf_event.h | 7 ++++--- kernel/perf_event.c | 27 ++++++++++++++++++++++----- 2 files changed, 26 insertions(+), 8 deletions(-) Index: linux-2.6/include/linux/perf_event.h =================================================================== --- linux-2.6.orig/include/linux/perf_event.h +++ linux-2.6/include/linux/perf_event.h @@ -1074,11 +1074,12 @@ perf_sw_event(u32 event_id, u64 nr, int __perf_sw_event(event_id, nr, nmi, regs, addr); } -extern atomic_t perf_sched_events; +extern atomic_t perf_sched_events_in; +extern atomic_t perf_sched_events_out; static inline void perf_event_task_sched_in(struct task_struct *task) { - COND_STMT(&perf_sched_events, __perf_event_task_sched_in(task)); + COND_STMT(&perf_sched_events_in, __perf_event_task_sched_in(task)); } static inline @@ -1086,7 +1087,7 @@ void perf_event_task_sched_out(struct ta { perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0); - COND_STMT(&perf_sched_events, __perf_event_task_sched_out(task, next)); + COND_STMT(&perf_sched_events_out, __perf_event_task_sched_out(task, next)); } extern void perf_event_mmap(struct vm_area_struct *vma); Index: linux-2.6/kernel/perf_event.c =================================================================== --- linux-2.6.orig/kernel/perf_event.c +++ linux-2.6/kernel/perf_event.c @@ -125,9 +125,25 @@ enum event_type_t { * perf_sched_events : >0 events exist * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu */ -atomic_t perf_sched_events __read_mostly; +atomic_t perf_sched_events_in __read_mostly; +atomic_t perf_sched_events_out __read_mostly; static DEFINE_PER_CPU(atomic_t, perf_cgroup_events); +static void perf_sched_events_inc(void) +{ + jump_label_inc(&perf_sched_events_out); + jump_label_inc(&perf_sched_events_in); +} + +static void perf_sched_events_dec(void) +{ + jump_label_dec(&perf_sched_events_in); + JUMP_LABEL(&perf_sched_events_in, no_sync); + synchronize_sched(); +no_sync: + jump_label_dec(&perf_sched_events_out); +} + static atomic_t nr_mmap_events __read_mostly; static atomic_t nr_comm_events __read_mostly; static atomic_t nr_task_events __read_mostly; @@ -2900,7 +2917,7 @@ static void free_event(struct perf_event if (!event->parent) { if (event->attach_state & PERF_ATTACH_TASK) - jump_label_dec(&perf_sched_events); + perf_sched_events_dec(); if (event->attr.mmap || event->attr.mmap_data) atomic_dec(&nr_mmap_events); if (event->attr.comm) @@ -2911,7 +2928,7 @@ static void free_event(struct perf_event put_callchain_buffers(); if (is_cgroup_event(event)) { atomic_dec(&per_cpu(perf_cgroup_events, event->cpu)); - jump_label_dec(&perf_sched_events); + perf_sched_events_dec(); } } @@ -6256,7 +6273,7 @@ perf_event_alloc(struct perf_event_attr if (!event->parent) { if (event->attach_state & PERF_ATTACH_TASK) - jump_label_inc(&perf_sched_events); + perf_sched_events_inc(); if (event->attr.mmap || event->attr.mmap_data) atomic_inc(&nr_mmap_events); if (event->attr.comm) @@ -6498,7 +6515,7 @@ SYSCALL_DEFINE5(perf_event_open, * - that may need work on context switch */ atomic_inc(&per_cpu(perf_cgroup_events, event->cpu)); - jump_label_inc(&perf_sched_events); + perf_sched_events_inc(); } /*