From: James Clark <james.clark@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
namhyung@kernel.org, linux-perf-users@vger.kernel.org,
leo.yan@linaro.com, Suzuki.Poulose@arm.com,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/1] perf/core: Wake up parent event if inherited event has no ring buffer
Date: Wed, 26 Jan 2022 16:15:30 +0000 [thread overview]
Message-ID: <b0de5ea6-4100-15ed-bbf8-8578a0fa5b6d@arm.com> (raw)
In-Reply-To: <YfBLusfOk9fpIqqI@hirez.programming.kicks-ass.net>
On 25/01/2022 19:12, Peter Zijlstra wrote:
> On Mon, Jan 24, 2022 at 02:58:18PM +0000, James Clark wrote:
>
>>> Would this be the better patch?
>>
>> Yes I tested this and it also works.
>
> Excellent!
>
>> There is one other suspicious access
>> of ->rb followed by if(rb) here in perf_poll(), but maybe it works out ok?
>>
>> mutex_lock(&event->mmap_mutex);
>> rb = event->rb;
>> if (rb)
>> events = atomic_xchg(&rb->poll, 0);
>>
>
> That case must be good since it is the event from a file. Those cannot
> be clones.
>
>> We also have a Perf self test that covers this failure for Arm SPE now, I'm not
>> sure if I should post that separately or with your new version of this fix?
>
> They'd be routed through separate trees anyway, Arnaldo takes the
> userspace stuff.
>
Ok we will post that one separately then. What are the next steps for this one?
Will you just put your version directly in your tree, or should I resubmit it with a
new commit message?
next prev parent reply other threads:[~2022-01-26 16:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 11:38 [RFC PATCH 0/1] perf/core: Wake up parent event if inherited event has no ring buffer James Clark
2021-12-06 11:38 ` [RFC PATCH 1/1] " James Clark
2022-01-24 11:37 ` Ruben Ayrapetyan
2022-01-24 11:49 ` Peter Zijlstra
2022-01-24 14:58 ` James Clark
2022-01-25 19:12 ` Peter Zijlstra
2022-01-26 16:15 ` James Clark [this message]
2022-01-27 11:50 ` [tip: perf/urgent] perf: Always wake the parent event tip-bot2 for James Clark
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