linux-kernel - Re: mplayer + heavy io: why ionice doesn't help?

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Message-Id: <1156268290.5069.2.camel@bip.parateam.prv>
Date:	Tue, 22 Aug 2006 19:38:10 +0200
From:	Xavier Bestel <xavier.bestel@...e.fr>
To:	Denis Vlasenko <vda.linux@...glemail.com>
Cc:	Lee Revell <rlrevell@...-job.com>,
	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	Eric Piel <Eric.Piel@...mplin-utc.net>,
	mplayer-users@...ayerhq.hu, linux-kernel@...r.kernel.org
Subject: Re: mplayer + heavy io: why ionice doesn't help?

Le mardi 22 août 2006 à 18:26 +0200, Denis Vlasenko a écrit :

> > I think the problem is also due to mplayer's faulty design.  It should
> > be multithreaded and use RT threads for the time sensitive work, like
> > all professional AV applications and many other consumer players do.
> 
> RT - yes, multithreaded - unsure. Witness how squid manages to
> serve hundreds of simultaneous streams using just a single process.
> 
> Multithreading seems cool on the first glance and it is easier to code
> than clever O_NONBLOCK/select/poll/etc stuff. However,
> on single-CPU boxes, which are still a majority, multithreading
> just incurs context switching penalty. It cannot magically
> make CPU do more work in a unit of time.

The problem with mplayer is latency more than throughput, and for that
multithreading is king. Squid can get away with a 100ms delay between
two packets, mplayer can't.

	Xav

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