linux-kernel - Re: [PATCH RFC] remove jump_label optimization for perf sched events

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Message-ID: <1321535413.27735.35.camel@twins>
Date:	Thu, 17 Nov 2011 14:10:12 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Gleb Natapov <gleb@...hat.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu,
	Jason Baron <jbaron@...hat.com>, rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH RFC] remove jump_label optimization for perf sched events

On Thu, 2011-11-17 at 15:00 +0200, Gleb Natapov wrote:

> > That said, I'd much rather throttle this particular jump label than
> > remove it altogether, some people really don't like all this scheduler
> > hot path crap.
> What about moving perf_event_task_sched() to sched_(in|out)_preempt_notifiers?
> preempt notifiers checking is already on the scheduler hot path, so no
> additional overhead for perf case.

Same problem really, some people complain about the overhead of preempt
notifiers, also not all kernels have those in. 

Futhermore I loathe notifier lists because they obscure wtf is done.
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