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From: Ingo Molnar <mingo@elte.hu>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Mike Galbraith <efault@gmx.de>, Robert Swan <swan.r.l@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [bisected] pty performance problem
Date: Mon, 23 Nov 2009 13:04:09 +0100	[thread overview]
Message-ID: <20091123120409.GA32009@elte.hu> (raw)
In-Reply-To: <20091123115949.29bcf89d@lxorguk.ukuu.org.uk>


* Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> > > Another possibility is to do
> > > 
> > > 	if (tty->low_latency)
> > > 		schedule_delayed_work(&tty->buf.work, 0);
> > > 	else
> > > 		schedule_delayed_work(&tty->buf.work, 1);
> > 
> > Flaggery for low latency is kind of lame though - especially if it 
> > defaults to off in most drivers as you say.
> 
> So you'd prefer to detect devices that are byte based or message based 
> by what method ?

I'd not delay the worklet by default - i.e. i'd do Mike's patch.

Havent tested all effects of it though - do you have any estimation 
about negative effects from such a change? We do have hard numbers 
(latencies in the millisecs range) from the opposite direction and those 
numbers arent pretty.

	Ingo

  reply	other threads:[~2009-11-23 12:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-21 22:23 Robert Swan
2009-11-21 23:23 ` Alan Cox
2009-11-22  0:27   ` Robert Swan
2009-11-22 12:29     ` Alan Cox
2009-11-22 12:41       ` Mike Galbraith
2009-11-22 21:37       ` Robert Swan
2009-11-22  6:39 ` Ingo Molnar
2009-11-22  7:15   ` Arjan van de Ven
2009-11-22 21:56     ` Robert Swan
2009-11-22 12:23   ` Alan Cox
2009-11-22 12:42     ` Ingo Molnar
2009-11-23  5:00     ` Mike Galbraith
2009-11-23 10:28       ` Alan Cox
2009-11-23 11:31       ` Alan Cox
2009-11-23 11:48         ` Ingo Molnar
2009-11-23 11:59           ` Alan Cox
2009-11-23 12:04             ` Ingo Molnar [this message]
2009-11-23 13:34               ` Alan Cox
2009-11-23 17:48                 ` Ingo Molnar
2011-07-09  6:29 ` Robert Swan

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