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From: Ingo Molnar <mingo@redhat.com>
To: Alexandre Oliva <aoliva@redhat.com>
Cc: jmoyer@redhat.com, "Stephen C. Tweedie" <sct@redhat.com>,
	Marcelo Tosatti <marcelo.tosatti@cyclades.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	akpm@osdl.org
Subject: Re: [patch rfc] towards supporting O_NONBLOCK on regular files
Date: Sun, 17 Oct 2004 07:20:14 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.58.0410170715240.16806@devserv.devel.redhat.com> (raw)
In-Reply-To: <orzn2lpyfc.fsf@livre.redhat.lsd.ic.unicamp.br>


On Sun, 17 Oct 2004, Alexandre Oliva wrote:

> The reason Squid breaks is that poll (or is it select? I forget) says
> there's data to be read from cache files (as well as from error message
> files read during start up), but then read fails with -EAGAIN. If I
> bring the error files into memory with cat /etc/squid/errors/ERR*, then
> squid will successfully start up, and then, in order for it to not eat
> all the available CPU polling data files and attempting to read from
> them, I need to start a command line this:

the problem is that upon read() we dont 'kick' any IO if there's no data
available. I.e. the readahead-kicking is necessary after all, because
squid apparently assumes that re-trying a read will eventually succeed.  
(Tux on the other hand does not assume this and uses helper threads to
kick IO.)

	Ingo

  reply	other threads:[~2004-10-17 11:21 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-01 20:57 Jeff Moyer
2004-10-03 19:48 ` Pavel Machek
2004-10-13 14:28   ` Jeff Moyer
2004-10-14 17:39     ` Pavel Machek
2004-10-05 11:27 ` Marcelo Tosatti
2004-10-06 13:13   ` Jeff Moyer
2004-10-06 12:01     ` Marcelo Tosatti
2004-10-07  3:31       ` Stephen C. Tweedie
2004-10-07 10:12         ` Marcelo Tosatti
2004-10-07 12:30           ` Arjan van de Ven
2004-10-11 18:32           ` Stephen C. Tweedie
2004-10-11 18:58             ` Jeff Moyer
2004-10-11 21:49               ` Stephen C. Tweedie
2004-10-13 14:26                 ` Jeff Moyer
2004-10-15 15:44                   ` Jeff Moyer
2004-10-15 16:19                     ` Stephen C. Tweedie
2004-10-17  7:59                     ` Alexandre Oliva
2004-10-17 11:20                       ` Ingo Molnar [this message]
2004-10-17 19:38                         ` Alexandre Oliva
2004-10-18 16:51                           ` Jeff Moyer
2004-10-19  6:04                             ` Alexandre Oliva
2004-10-21 20:14                             ` James Antill
2004-10-05 15:35 ` Rik van Riel
2004-10-05 13:07 Dan Kegel

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