From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>
Subject: Re: [PATCH v1 4/5] perf: Introduce address range filtering
Date: Mon, 25 Apr 2016 15:10:13 +0200 [thread overview]
Message-ID: <20160425131013.GD3448@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <87zisl8vls.fsf@ashishki-desk.ger.corp.intel.com>
On Fri, Apr 22, 2016 at 07:19:11PM +0300, Alexander Shishkin wrote:
> +static int perf_event_restart(struct perf_event *event)
> +{
> + struct stop_event_data sd = {
> + .event = event,
> + .restart = 1,
> + };
> + int ret = 0;
> +
> + do {
> + if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
> + return 0;
> +
> + /* matches smp_wmb() in event_sched_in() */
> + smp_rmb();
> +
> + ret = cpu_function_call(READ_ONCE(event->oncpu),
> + __perf_event_stop, &sd);
> + } while (ret == -EAGAIN);
> +
> + return ret;
> +}
A few concerns with this;
- if I understand things right; this will loose a bit of trace when
people tickle the ioctl(), right? This might want a note of sorts,
- you need to handle event->oncpu == -1,
- can we race with an actual stop, and accidentally re-enable the
thing? If not, this might be a good place for a comment explaining
how.
next prev parent reply other threads:[~2016-04-25 13:10 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 15:16 [PATCH v1 0/5] perf: Introduce address range filtering Alexander Shishkin
2016-04-21 15:16 ` [PATCH v1 1/5] perf: Move set_filter() from behind EVENT_TRACING Alexander Shishkin
2016-04-21 15:17 ` [PATCH v1 2/5] perf/x86/intel/pt: IP filtering register/cpuid bits Alexander Shishkin
2016-04-21 17:48 ` Borislav Petkov
2016-04-21 18:55 ` Thomas Gleixner
2016-04-21 19:17 ` Peter Zijlstra
2016-04-21 20:39 ` Borislav Petkov
2016-04-21 20:37 ` Borislav Petkov
2016-04-22 7:58 ` Thomas Gleixner
2016-04-22 9:34 ` Borislav Petkov
2016-04-21 15:17 ` [PATCH v1 3/5] perf: Extend perf_event_aux_ctx() to optionally iterate through more events Alexander Shishkin
2016-04-21 15:17 ` [PATCH v1 4/5] perf: Introduce address range filtering Alexander Shishkin
2016-04-22 7:45 ` Peter Zijlstra
2016-04-22 16:19 ` Alexander Shishkin
2016-04-25 12:57 ` Peter Zijlstra
2016-04-25 15:41 ` Alexander Shishkin
2016-04-25 13:10 ` Peter Zijlstra [this message]
2016-04-25 13:36 ` Peter Zijlstra
2016-04-25 16:02 ` Alexander Shishkin
2016-04-25 13:19 ` Peter Zijlstra
2016-04-25 16:03 ` Alexander Shishkin
2016-04-25 14:14 ` Peter Zijlstra
2016-04-25 16:07 ` Alexander Shishkin
2016-04-25 14:25 ` Peter Zijlstra
2016-04-25 16:14 ` Alexander Shishkin
2016-04-26 14:35 ` Alexander Shishkin
2016-04-21 15:17 ` [PATCH v1 5/5] perf/x86/intel/pt: Add support for address range filtering in PT Alexander Shishkin
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