From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: linux-kernel@vger.kernel.org, Jiri Olsa <jolsa@redhat.com>,
Alexander Yarygin <yarygin@linux.vnet.ibm.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>, Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH 2/5] perf: Destroy event's children on task exit
Date: Fri, 11 Jul 2014 15:23:09 +0200 [thread overview]
Message-ID: <20140711132309.GH20603@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <1405079782-8139-3-git-send-email-jolsa@kernel.org>
On Fri, Jul 11, 2014 at 01:56:19PM +0200, Jiri Olsa wrote:
> From: Jiri Olsa <jolsa@redhat.com>
>
> When task exits we close:
> 1) all events that are installed in task
> 2) all events owned by task (via file descriptor)
>
> But we don't close children events of 2) events. Those children
> events stay until the child task exits and are useless with the
> parent being gone, because we have no way to get to values any
> more.
>
> Plus if the event stays installed in task even with the owner task
> gone, it runs the perf callback any time the task forks, for no
> real reason.
>
> Closing all children events events when the owner task of the
> parent event is closed.
So I _think_ the reason we didn't do this is because this is potentially
very expensive and keeping them around isn't too much bother, they'll
die eventually.
But I can't really remember. Ingo any recollections / opinions?
next prev parent reply other threads:[~2014-07-11 13:23 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-11 11:56 [PATCH 0/5] perf: Fix tracepoint events permissions check Jiri Olsa
2014-07-11 11:56 ` [PATCH 1/5] perf: Make perf_init_event function static Jiri Olsa
2014-07-11 11:56 ` [PATCH 2/5] perf: Destroy event's children on task exit Jiri Olsa
2014-07-11 13:23 ` Peter Zijlstra [this message]
2014-07-11 13:31 ` Jiri Olsa
2014-07-16 12:20 ` Ingo Molnar
2014-07-14 11:18 ` Peter Zijlstra
2014-07-14 11:43 ` Jiri Olsa
2014-07-14 13:02 ` Peter Zijlstra
2014-07-14 13:22 ` Jiri Olsa
2014-07-14 13:35 ` Peter Zijlstra
2014-07-14 14:21 ` Jiri Olsa
2014-07-16 12:14 ` Jiri Olsa
2014-07-14 20:18 ` Jiri Olsa
2014-07-15 9:11 ` Peter Zijlstra
2014-07-15 9:31 ` Jiri Olsa
2014-07-11 11:56 ` [PATCH 3/5] perf: Initialize owner before calling event_init callback Jiri Olsa
2014-07-11 11:56 ` [PATCH 4/5] perf: Move event owner retrieval into perf_event_get_owner Jiri Olsa
2014-07-11 11:56 ` [PATCH 5/5] perf: Check event's owner permission in tracepoint init callback Jiri Olsa
2014-07-11 12:02 ` [PATCH 0/5] perf: Fix tracepoint events permissions check Jiri Olsa
2014-07-28 8:28 ` [tip:perf/core] perf: Check permission only for parent tracepoint event tip-bot for Jiri Olsa
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