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From: Helge Hafting <helgehaf@aitel.hist.no>
To: Giuliano Pochini <pochini@shiny.it>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] O_STREAMING - flag for optimal streaming I/O
Date: Thu, 10 Oct 2002 13:01:32 +0200	[thread overview]
Message-ID: <3DA55E0C.24033BB5@aitel.hist.no> (raw)
In-Reply-To: XFMail.20021010113849.pochini@shiny.it

Giuliano Pochini wrote:

> Yes, it makes sense, but it's useless or harmful to discard caches
> if nobody else needs memory. You just lose data that may be
> requested in the future for no reason.

Sure, so the ideal is to not drop unconditionally, but
make sure that the "finished" O_STREAMING pages are
the very first ones to go whenever memory pressure happens.

The question then becomes "can you do that, with no more
overhead or code complexity than the existing stuff?"

It wouldn't necessarily make much difference, because
a linux machine is almost always under memory pressure.
Free memory is simply filled up with cache till there
is no more left.  From then on, all requests for memory
are handled by throwing something else out of cache
or into swap.  In that case the streaming pages
are evicted quickly anyway, and the ideal case
is no different from the implemented case.

Helge Hafting

  parent reply	other threads:[~2002-10-10 10:55 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-08  2:38 [PATCH] O_STREAMING - flag for optimal streaming I/O Robert Love
2002-10-08 10:42 ` J.A. Magallon
2002-10-08 18:08   ` Robert Love
2002-10-08 18:38 ` Chris Wedgwood
2002-10-08 18:49   ` Robert Love
2002-10-08 19:05     ` Chris Wedgwood
2002-10-08 19:17       ` Robert Love
2002-10-08 19:30         ` Andrew Morton
2002-10-09 14:14           ` Marco Colombo
2002-10-09 16:30           ` kernel
2002-10-08 19:52         ` Chris Wedgwood
2002-10-08 19:59           ` Robert Love
2002-10-08 20:01             ` Chris Wedgwood
2002-10-09  8:33         ` Giuliano Pochini
2002-10-09  8:43           ` Andrew Morton
2002-10-09 10:55             ` Giuliano Pochini
2002-10-09 17:05           ` Mark Mielke
2002-10-09 19:36             ` Giuliano Pochini
2002-10-09 22:24               ` Mark Mielke
2002-10-09 23:20                 ` Jamie Lokier
2002-10-10  3:07                   ` Mark Mielke
2002-10-10 10:55                     ` Helge Hafting
2002-10-10 17:50                       ` Mark Mielke
2002-10-10  3:29                   ` Erik Andersen
2002-10-10  3:37                     ` Robert Love
2002-10-10 13:39                       ` Giuliano Pochini
2002-10-10 22:50                         ` Mike Fedyk
2002-10-10 22:58                           ` Erik Andersen
2002-10-11  8:26                           ` Giuliano Pochini
2002-10-11  8:32                           ` Helge Hafting
2002-10-10  8:33                     ` Giuliano Pochini
2002-10-10  9:10                       ` Erik Andersen
2002-10-10  9:38                         ` Giuliano Pochini
2002-10-10 10:40                           ` Miquel van Smoorenburg
2002-10-10 11:01                           ` Helge Hafting [this message]
2002-10-10 12:29                             ` Xavier Bestel
2002-10-10 13:17                             ` Giuliano Pochini
2002-10-10 22:44                               ` Mike Fedyk
2002-10-11  8:13                                 ` Giuliano Pochini
2002-10-10 11:38                     ` O_STREAMING has insufficient info - how about fadvise() ? Alan Cox
2002-10-10 11:47                       ` William Lee Irwin III
2002-10-10 15:34                       ` Andrew Morton
2002-10-10 16:08                         ` Alan Cox
2002-10-10 16:49                         ` Oliver Xymoron
2002-10-10 15:37                     ` [PATCH] O_STREAMING - flag for optimal streaming I/O Gerhard Mack
2002-10-10 22:47                       ` Mike Fedyk
2002-10-11  2:14                         ` Gerhard Mack
2002-10-11  8:10                           ` Chris Wedgwood
2002-10-10  9:14                 ` David Lang
2002-10-10 14:51               ` Denis Vlasenko
2002-10-08 19:53       ` Matthias Schniedermeyer
2002-10-08 19:59         ` Chris Wedgwood
2002-10-08 20:03         ` Andrew Morton
2002-10-08 20:34           ` Matthias Schniedermeyer
2002-10-08 20:42             ` Andrew Morton
2002-10-08 20:37           ` Larry McVoy
2002-10-09 11:53 ` Roy Sigurd Karlsbakk
2002-10-09 14:10 ` Marco Colombo
2002-10-09 14:14   ` Robert Love
2002-10-09 14:33     ` Richard B. Johnson
2002-10-09 15:27     ` Andreas Dilger
2002-10-09 23:17       ` Jamie Lokier
2002-10-09 23:46       ` Rik van Riel
2002-10-10  0:16         ` Jamie Lokier
2002-10-10  2:39           ` Erik Andersen
2002-10-10 10:33         ` Marco Colombo
2002-10-10 20:00           ` Erik Andersen
2002-10-11  4:16 Hank Leininger

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