linux-kernel - Re: Network slowdown due to CFS

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Message-ID: <20071001162507.GA22791@elte.hu>
Date:	Mon, 1 Oct 2007 18:25:07 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jarek Poplawski <jarkao2@...pl>
Cc:	Nick Piggin <nickpiggin@...oo.com.au>,
	David Schwartz <davids@...master.com>,
	linux-kernel@...r.kernel.org, Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Martin Michlmayr <tbm@...ius.com>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Stephen Hemminger <shemminger@...ux-foundation.org>
Subject: Re: Network slowdown due to CFS

* Jarek Poplawski <jarkao2@...pl> wrote:

> BTW, it looks like risky to criticise sched_yield too much: some 
> people can misinterpret such discussions and stop using this at all, 
> even where it's right.

Really, i have never seen a _single_ mainstream app where the use of 
sched_yield() was the right choice.

Fortunately, the sched_yield() API is already one of the most rarely 
used scheduler functionalities, so it does not really matter. [ In my 
experience a Linux scheduler is stabilizing pretty well when the 
discussion shifts to yield behavior, because that shows that everything 
else is pretty much fine ;-) ]

But, because you assert it that it's risky to "criticise sched_yield() 
too much", you sure must know at least one real example where it's right 
to use it (and cite the line and code where it's used, with 
specificity)?

	Ingo
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