From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Will Deacon <will.deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 3/3] perf: Allow kernel filters on cpu events
Date: Fri, 27 Jan 2017 14:31:22 +0200 [thread overview]
Message-ID: <87efzobs6d.fsf@ashishki-desk.ger.corp.intel.com> (raw)
In-Reply-To: <20170126213855.GC1991@linaro.org>
Mathieu Poirier <mathieu.poirier@linaro.org> writes:
> On Thu, Jan 26, 2017 at 11:40:57AM +0200, Alexander Shishkin wrote:
>> + if (!ifh->nr_file_filters)
>> + return;
>
> Is this mandatory or an optimisation to avoid circling through a list of filters
> that don't included user space files?
It's both. It stems from the fact that the remainder of this function
relies on ctx::task not being NULL, which is not the case with cpu
contexts and now that we've enabled address filters for such contexts,
it's a problem. So checking for !task would have done the trick here,
but this way we'll also avoid going down this path for task contexts
in the absence of file-based filters. In particular, grabbing the mmap
semaphore and filters spinlock we can do without.
Regards,
--
Alex
next prev parent reply other threads:[~2017-01-27 12:42 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-26 9:40 [PATCH 0/3] perf: Updates for address filters Alexander Shishkin
2017-01-26 9:40 ` [PATCH 1/3] perf, pt, coresight: Clean up address filter structure Alexander Shishkin
2017-01-26 13:02 ` kbuild test robot
2017-01-26 13:24 ` Alexander Shishkin
2017-01-26 18:26 ` Mathieu Poirier
2017-01-27 12:12 ` Alexander Shishkin
2017-01-27 17:17 ` Mathieu Poirier
2017-02-01 12:46 ` Alexander Shishkin
2017-02-01 21:33 ` Mathieu Poirier
2017-02-01 22:15 ` Mathieu Poirier
2017-02-02 10:42 ` Alexander Shishkin
2017-02-02 17:36 ` Mathieu Poirier
2017-02-02 16:22 ` Alexander Shishkin
2017-02-07 17:50 ` Mathieu Poirier
[not found] ` <20180117123137.3hlmudzu5eogl53n@ukko.fi.intel.com>
2018-01-18 16:59 ` Mathieu Poirier
2018-01-18 17:06 ` Will Deacon
2018-01-18 18:19 ` Mathieu Poirier
2018-01-19 18:50 ` Mathieu Poirier
2017-01-26 9:40 ` [PATCH 2/3] perf: Do error out on a kernel filter on an exclude_filter event Alexander Shishkin
2017-01-26 18:32 ` Mathieu Poirier
2017-02-10 8:33 ` [tip:perf/core] perf/core: " tip-bot for Alexander Shishkin
2017-01-26 9:40 ` [PATCH 3/3] perf: Allow kernel filters on cpu events Alexander Shishkin
2017-01-26 21:38 ` Mathieu Poirier
2017-01-27 12:31 ` Alexander Shishkin [this message]
2017-01-27 17:38 ` Mathieu Poirier
2017-02-10 8:07 ` Ingo Molnar
2017-02-14 12:59 ` Alexander Shishkin
2017-02-10 8:34 ` [tip:perf/core] perf/core: Allow kernel filters on CPU events tip-bot for Alexander Shishkin
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