From: Tejun Heo <tj@kernel.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
efault@gmx.de, avi@redhat.com, paulus@samba.org, acme@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCHSET] sched,perf: unify tracers in sched and move perf on top of TP
Date: Thu, 06 May 2010 10:41:14 +0200 [thread overview]
Message-ID: <4BE280AA.6020304@kernel.org> (raw)
In-Reply-To: <20100506082714.GA2036@elte.hu>
Hello, Ingo.
On 05/06/2010 10:27 AM, Ingo Molnar wrote:
> Note that preempt notifiers used to modify scheduling behavior/semantics i'm
> really against. Please get that functionality into the scheduler - especially
> if it's essentially always-on.
Okay. Well, cmwq's usage of it isn't that hairy. It's used for two
things.
1. to count the number of currently running workers which I think is
fine for such hooks.
2. to wake up another worker. I don't think this falls in the
category of "behavior/semantics" change. It just does
try_to_wake_up() with the only caveat being it's called under the
rq lock so requires a different API. There's nothing which alters
the scheduler behavior in any pervasive way. It just looks at the
counter and wakes up another task if the condition is right
*before* beginning any of real scheduling work.
But, anyways, making a dedicated fixed function calls certainly isn't
a problem and might as well be slightly cheaper as it's always gonna
be there anyway. If that's preferred, I'll happily take that path.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-05-06 8:42 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-04 12:38 [RFC PATCHSET] sched,perf: unify tracers in sched and move perf on top of TP Tejun Heo
2010-05-04 12:38 ` [PATCH 01/12] sched: drop @cpu argument from sched_in preempt notifier Tejun Heo
2010-05-04 17:11 ` Peter Zijlstra
2010-05-04 12:38 ` [PATCH 02/12] sched: rename preempt_notifiers to sched_notifiers and refactor implementation Tejun Heo
2010-05-04 12:38 ` [PATCH 03/12] perf: add perf_event_task_migrate() Tejun Heo
2010-05-05 5:08 ` Frederic Weisbecker
2010-05-05 5:16 ` Tejun Heo
2010-05-05 9:11 ` Peter Zijlstra
2010-05-05 9:37 ` Tejun Heo
2010-05-05 9:50 ` Peter Zijlstra
2010-05-05 9:56 ` Tejun Heo
2010-05-04 12:38 ` [PATCH 04/12] perf: add @rq to perf_event_task_sched_out() Tejun Heo
2010-05-04 17:11 ` Peter Zijlstra
2010-05-04 17:22 ` Tejun Heo
2010-05-04 17:42 ` Peter Zijlstra
2010-05-04 18:22 ` Steven Rostedt
2010-05-04 18:26 ` Peter Zijlstra
2010-05-04 18:32 ` Steven Rostedt
2010-05-05 4:48 ` Tejun Heo
2010-05-05 9:58 ` Tejun Heo
2010-05-07 18:41 ` [tip:sched/core] sched: Remove rq argument to the tracepoints tip-bot for Peter Zijlstra
2010-05-04 12:38 ` [PATCH 05/12] perf: move perf_event_task_sched_in() next to fire_sched_notifiers_in() Tejun Heo
2010-05-04 12:38 ` [PATCH 06/12] sched: relocate fire_sched_notifiers_out() and trace_sched_switch() Tejun Heo
2010-05-04 12:38 ` [PATCH 07/12] sched: coalesce event notifiers Tejun Heo
2010-05-04 12:38 ` [PATCH 08/12] sched: add switch_in and tick tracepoints Tejun Heo
2010-05-04 12:38 ` [PATCH 09/12] perf: factor out perf_event_switch_clones() Tejun Heo
2010-05-04 12:38 ` [PATCH 10/12] perf: make nr_events an int and add perf_online_mutex to protect it Tejun Heo
2010-05-04 12:38 ` [PATCH 11/12] perf: prepare to move sched perf functions on top of tracepoints Tejun Heo
2010-05-04 12:38 ` [PATCH 12/12] perf: " Tejun Heo
2010-05-04 17:29 ` [RFC PATCHSET] sched,perf: unify tracers in sched and move perf on top of TP Peter Zijlstra
2010-05-05 5:00 ` Tejun Heo
2010-05-05 9:06 ` Peter Zijlstra
2010-05-05 9:32 ` Tejun Heo
2010-05-05 9:51 ` Peter Zijlstra
2010-05-05 9:54 ` Tejun Heo
2010-05-05 11:38 ` Peter Zijlstra
2010-05-05 12:28 ` Tejun Heo
2010-05-05 16:55 ` Ingo Molnar
2010-05-05 18:12 ` Peter Zijlstra
2010-05-05 18:16 ` Peter Zijlstra
2010-05-05 18:30 ` Frederic Weisbecker
2010-05-06 6:28 ` Ingo Molnar
2010-05-06 7:11 ` Tejun Heo
2010-05-06 8:27 ` Ingo Molnar
2010-05-06 8:41 ` Tejun Heo [this message]
2010-05-06 8:18 ` Avi Kivity
2010-05-06 6:31 ` Ingo Molnar
2010-05-06 7:04 ` Peter Zijlstra
2010-05-06 7:11 ` Ingo Molnar
2010-05-06 7:29 ` Tejun Heo
2010-05-06 7:33 ` Tejun Heo
2010-05-05 12:33 ` Avi Kivity
2010-05-05 13:09 ` Tejun Heo
2010-05-10 5:20 ` Paul Mackerras
2010-05-10 5:48 ` Tejun Heo
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