Date: Sun, 22 Nov 2009 13:42:09 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Robert Swan <swan.r.l@gmail.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       linux-kernel@vger.kernel.org, Arjan van de Ven <arjan@infradead.org>
Subject: Re: [bisected] pty performance problem
Message-ID: <20091122124209.GA30965@elte.hu>
References: <20091121222319.GA3905@swanrl.gmail.com>
 <20091122063926.GA18224@elte.hu>
 <20091122122312.71a343d9@lxorguk.ukuu.org.uk>
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* Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> On Sun, 22 Nov 2009 07:39:26 +0100
> Ingo Molnar <mingo@elte.hu> wrote:
> 
> > 
> > (Cc:-ed Alan and Linus - mail repeated below. eot.)
> 
> I saw it and replied already. The kernel now queues the work for the 
> pty as it does normal tty devices. If the CPU load is that low and 
> nothing else is happening it makes me wonder what the scheduler thinks 
> it is doing ?

Would be nice to see the testcase, but by the looks if it there appears 
to be a jiffy delay somewhere - not a scheduler delay. On an idle box 
the scheduler will run any runnable tasks, with no delay.

	Ingo
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