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From: Oliver Neukum <oliver@neukum.name>
To: Xuan Baldauf <xuan--reiserfs@baldauf.org>
Cc: Rik van Riel <riel@conectiva.com.br>, linux-kernel@vger.kernel.org
Subject: Re: Heuristic readahead for filesystems
Date: Wed, 11 Sep 2002 21:04:41 +0200	[thread overview]
Message-ID: <200209112104.41987.oliver@neukum.name> (raw)
In-Reply-To: <3D7F8ECA.21086A5@baldauf.org>

Am Mittwoch, 11. September 2002 20:43 schrieb Xuan Baldauf:

> > Please correct me, if I am wrong, but wouldn't read() block ?
>
> AFAIK, "man open" tells
>
> [...]
>       int open(const char *pathname, int flags);
> [...]
>        O_NONBLOCK or O_NDELAY
>                The file is opened in non-blocking mode. Neither the open
> nor any __subsequent__ operations  on  the  file  descriptor
>                which is returned will cause the calling process to wait.
> [...]
>
> So read won't block if the file has been opened with O_NONBLOCK.

Well, so the man page tells you. The kernel sources tell otherwise, unless
I am badly mistaken.

> > Aio should be able to do it. But even that want help you with the stat
> > data.
>
> Aio would help me announcing stat() usage for the future?

No, it won't. But it would solve the issue of reading ahead.
Stating needs a kernel implementation of 'stat ahead'

  reply	other threads:[~2002-09-11 19:02 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-09-11 15:42 Xuan Baldauf
2002-09-11 16:33 ` Davide Libenzi
2002-09-11 17:03   ` jdow
2002-09-11 17:20     ` Davide Libenzi
2002-09-11 17:51       ` jdow
2002-09-11 17:16   ` Hans Reiser
2002-09-11 16:42 ` Rik van Riel
2002-09-11 17:20   ` Oliver Neukum
2002-09-11 17:56   ` Xuan Baldauf
2002-09-11 18:30     ` Oliver Neukum
2002-09-11 18:43       ` Xuan Baldauf
2002-09-11 19:04         ` Oliver Neukum [this message]
2002-09-11 19:21           ` Richard B. Johnson
2002-09-12  0:45             ` jw schultz
2002-09-12  1:58               ` Andrew Morton
2002-09-12 11:41               ` Richard B. Johnson
2002-09-12 13:35                 ` jw schultz
2002-09-12 21:33                 ` jdow
2002-09-16 12:52                   ` Richard B. Johnson
2002-09-17  1:45                     ` jdow
2002-09-17 10:37                       ` jbradford
2002-09-17  5:19                     ` jdow
2002-09-12 12:41               ` Jesse Pollard
2002-09-11 19:03   ` Tomas Szepe

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