linux-kernel - Re: [PATCH 6/8] perf: Account freq events per cpu

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Date:	Thu, 1 Aug 2013 14:48:29 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 6/8] perf: Account freq events per cpu

On Thu, Aug 01, 2013 at 02:46:58PM +0200, Jiri Olsa wrote:
> On Tue, Jul 23, 2013 at 02:31:04AM +0200, Frederic Weisbecker wrote:
> > This is going to be used by the full dynticks subsystem
> > as a finer-grained information to know when to keep and
> > when to stop the tick.
> > 
> > Original-patch-by: Peter Zijlstra <peterz@...radead.org>
> > Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
> > Cc: Jiri Olsa <jolsa@...hat.com>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Namhyung Kim <namhyung@...nel.org>
> > Cc: Ingo Molnar <mingo@...nel.org>
> > Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Cc: Stephane Eranian <eranian@...gle.com>
> > ---
> >  kernel/events/core.c |    7 +++++++
> >  1 files changed, 7 insertions(+), 0 deletions(-)
> > 
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index b40c3db..f9bd39b 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -141,6 +141,7 @@ enum event_type_t {
> >  struct static_key_deferred perf_sched_events __read_mostly;
> >  static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
> >  static DEFINE_PER_CPU(atomic_t, perf_branch_stack_events);
> > +static DEFINE_PER_CPU(atomic_t, perf_freq_events);
> >  
> >  static atomic_t nr_mmap_events __read_mostly;
> >  static atomic_t nr_comm_events __read_mostly;
> > @@ -3139,6 +3140,9 @@ static void unaccount_event_cpu(struct perf_event *event, int cpu)
> >  	}
> >  	if (is_cgroup_event(event))
> >  		atomic_dec(&per_cpu(perf_cgroup_events, cpu));
> > +
> > +	if (event->attr.freq)
> > +		atomic_dec(&per_cpu(perf_freq_events, cpu));
> >  }
> >  
> >  static void unaccount_event(struct perf_event *event)
> > @@ -6473,6 +6477,9 @@ static void account_event_cpu(struct perf_event *event, int cpu)
> >  	}
> >  	if (is_cgroup_event(event))
> >  		atomic_inc(&per_cpu(perf_cgroup_events, cpu));
> > +
> > +	if (event->attr.freq)
> > +		atomic_inc(&per_cpu(perf_freq_events, cpu));
> 
> cpu could be -1 in here.. getting:
> 
> [  178.901881] BUG: unable to handle kernel paging request at 0000000f001cf45a
> [  178.901989] IP: [<ffffffff8110c32b>] account_event_cpu+0xbb/0xd0
> [  178.901989] PGD 751a5067 PUD 0 
> [  178.901989] Oops: 0002 [#2] PREEMPT SMP 
> [  178.901989] Modules linked in:
> [  178.901989] CPU: 0 PID: 1309 Comm: perf Tainted: G      D W    3.11.0-rc3+ #281
> [  178.901989] Hardware name: Intel Corporation Montevina platform/To be filled by O.E.M., BIOS AMVACRB1.86C.0066.B00.0805070703 05/07/2008
> [  178.901989] task: ffff88007519e5c0 ti: ffff880074c08000 task.ti: ffff880074c08000
> [  178.901989] RIP: 0010:[<ffffffff8110c32b>]  [<ffffffff8110c32b>] account_event_cpu+0xbb/0xd0
> [  178.901989] RSP: 0018:ffff880074c09e38  EFLAGS: 00010216
> [  178.901989] RAX: 0000000f001cf45a RBX: ffff880074c1a800 RCX: 0000000000100000
> [  178.901989] RDX: 000000000000002c RSI: 000000000000002c RDI: ffff880000120400
> [  178.901989] RBP: ffff880074c09e48 R08: 0000000000000000 R09: 00000000ffffffff
> [  178.901989] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffff
> [  178.901989] R13: ffff880074c0e640 R14: 00000000ffffffff R15: 0000000000000000
> [  178.901989] FS:  00007fc670738980(0000) GS:ffff88007a600000(0000) knlGS:0000000000000000
> [  178.901989] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  178.901989] CR2: 0000000f001cf45a CR3: 00000000751a8000 CR4: 00000000000407f0
> [  178.901989] Stack:
> [  178.901989]  ffff880074c1a800 ffff880074c09ee8 ffff880074c09e68 ffffffff8110c3b6
> [  178.901989]  00000000ffffffff ffff880074c1a800 ffff880074c09f78 ffffffff81113ae8
> [  178.901989]  0000000000000000 0000000000000001 ffff880074c09eb8 ffffffff00000060
> [  178.901989] Call Trace:
> [  178.901989]  [<ffffffff8110c3b6>] account_event.part.66+0x76/0xa0
> [  178.901989]  [<ffffffff81113ae8>] SyS_perf_event_open+0x678/0xdf0
> [  178.901989]  [<ffffffff8100ed42>] ? syscall_trace_leave+0xb2/0x240
> [  178.901989]  [<ffffffff81641512>] tracesys+0xd0/0xd5
> [  178.901989] Code: d4 48 c7 c0 28 f4 1c 00 48 03 04 d5 80 ad ce 81 f0 ff 00 f6 83 c9 00 00 00 04 74 a7 48 c7 c0 4c f4 1c 00 4a 03 04 e5 80 ad ce 81 <f0> ff 00 5b 41 5c 5d c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 
> [  178.901989] RIP  [<ffffffff8110c32b>] account_event_cpu+0xbb/0xd0
> [  178.901989]  RSP <ffff880074c09e38>
> [  178.901989] CR2: 0000000f001cf45a
> [  179.122749] ---[ end trace 6f2f4f69b01368fb ]---

the testcase was:

[root@...p-26-214 tracing]# cat
...
[root@...p-26-214 perf]# ./perf record -p `pgrep cat`
Killed

jirka
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