Date: Mon, 3 Nov 2008 11:29:16 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Dimitri Sivanich <sivanich@sgi.com>, linux-kernel@vger.kernel.org,
       "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] small optimization to update_curr_rt
Message-ID: <20081103102916.GK13671@elte.hu>
References: <20081031130341.GA12018@sgi.com> <1225707724.7803.1612.camel@twins>
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* Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, 2008-10-31 at 08:03 -0500, Dimitri Sivanich wrote:
> > A very minor improvement, but might it be better to check sched_rt_runtime(rt_rq)
> > before taking the rt_runtime_lock?
> 
> Yes, I think its ok to do so.
> 
> Like pointed out in the other thread, there are two races:
> 
>  - sched_rt_runtime() going to RUNTIME_INF, and that will be handled
>    properly by sched_rt_runtime_exceeded()
> 
>  - sched_rt_runtime() going to !RUNTIME_INF, and here we can miss an
>    accounting cycle, but I don't think that is something to worry too
>    much about.
> 
> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

applied to tip/sched/rt, thanks guys!

	Ingo
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