From: "Dan Maas" <dmaas@dcine.com>
To: "Rik van Riel" <riel@conectiva.com.br>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: Swap
Date: Tue, 20 Nov 2001 16:26:57 -0500 [thread overview]
Message-ID: <037701c1720a$159ee9a0$1a01a8c0@allyourbase> (raw)
In-Reply-To: <fa.kmf405v.j74f21@ifi.uio.no> <fa.ns5ugpv.q02sbg@ifi.uio.no>
> I bet they're getting mmap()d, like all mp3 programs seem to do
Just a note here - I see much fewer buffer underruns and more consistent
read-ahead/drop-behind behavior (i.e. no paging of other programs) when
using plain read(), as opposed to mmap(). This is in a video playback
program that pumps 3.6MB/sec!
MP3 datarates are less than 50KB/sec, so I don't really see why they stand
to benefit from mmap()... With mmap() you pay the extra cost of setting
up/tearing down the mapping, and the kernel->user copy is virtually
insignificant anyway (you already are paying for a single copy plus cache
pollution when moving the data from filesystem buffer to sound card DMA
buffer, so a second copy isn't a big deal)...
Regards,
Dan
next parent reply other threads:[~2001-11-20 21:39 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fa.kmf405v.j74f21@ifi.uio.no>
[not found] ` <fa.ns5ugpv.q02sbg@ifi.uio.no>
2001-11-20 21:26 ` Dan Maas [this message]
2001-11-20 22:05 ` Swap Rik van Riel
2001-11-20 22:11 ` Swap David S. Miller
2001-11-20 22:19 ` Swap Rik van Riel
2001-11-20 22:34 ` Swap Dan Maas
2001-11-20 23:05 ` Swap Andrew Morton
[not found] ` <fa.jc73ejv.1s6e80t@ifi.uio.no>
2001-11-21 1:45 ` Swap Håvard Kvålen
2001-11-21 4:23 ` Swap Andreas Dilger
2001-11-20 22:23 ` Swap Andrew Morton
2001-11-20 23:01 ` Swap David S. Miller
2001-11-20 23:35 ` Swap Rik van Riel
2001-11-20 23:40 ` Swap David S. Miller
2001-11-21 0:19 ` Swap Rik van Riel
2001-11-21 0:21 ` Swap David S. Miller
[not found] <fa.kb6ct7v.pgku0d@ifi.uio.no>
[not found] ` <fa.k8qdvcv.184ak2l@ifi.uio.no>
2001-11-20 22:46 ` Swap Dan Maas
2001-11-20 23:17 ` Swap Trond Myklebust
[not found] <fa.inl6g6v.1mmbp4@ifi.uio.no>
[not found] ` <fa.heevhav.sjs8an@ifi.uio.no>
2001-11-18 22:15 ` Swap Dan Maas
2001-11-18 22:43 ` Swap François Cami
2001-11-19 9:18 ` Swap James A Sutherland
2001-11-19 10:51 ` Swap Remco Post
2001-11-19 13:33 ` Swap James A Sutherland
2001-11-19 13:46 ` Swap Remco Post
2001-11-19 16:58 ` Swap Rik van Riel
[not found] ` <Pine.LNX.4.33L.0111191458150.1491-100000@duckman.distro.conecti va>
2001-11-19 21:13 ` Swap Alex Bligh - linux-kernel
2001-11-19 21:17 ` Swap Rik van Riel
[not found] ` <Pine.LNX.4.33L.0111191917000.1491-100000@duckman.distro.conecti va>
2001-11-19 21:52 ` Swap Alex Bligh - linux-kernel
2001-11-19 16:36 ` Swap Jesse Pollard
2001-11-20 14:51 ` Swap J.A. Magallon
2001-11-20 16:01 ` Swap Wolfgang Rohdewald
2001-11-20 16:06 ` Swap Remco Post
2001-11-20 16:12 ` Swap Nick LeRoy
2001-11-20 16:20 ` Swap Richard B. Johnson
2001-11-20 17:14 ` Swap Christopher Friesen
2001-11-20 17:40 ` Swap Richard B. Johnson
2001-11-20 18:14 ` Swap Nick LeRoy
2001-11-21 10:17 ` Swap Helge Hafting
2001-11-21 11:17 ` Swap Alan Cox
2001-11-20 23:20 ` Swap Luigi Genoni
2001-11-21 16:44 ` Swap Remco Post
2001-11-20 17:58 ` Swap Wolfgang Rohdewald
2001-11-20 21:05 ` Swap Steffen Persvold
2001-11-20 21:18 ` Swap Mike Fedyk
2001-11-20 21:33 ` Swap Nick LeRoy
2001-11-20 21:44 ` Swap Mike Fedyk
2001-11-20 22:00 ` Swap Nick LeRoy
2001-11-21 16:53 ` Swap Remco Post
2001-11-20 21:43 ` Swap Richard B. Johnson
2001-11-20 21:19 ` Swap Nick LeRoy
2001-11-21 16:48 ` Swap Remco Post
2001-11-20 20:58 ` Swap Mike Fedyk
2001-11-19 10:03 ` Swap Tim Connors
2001-11-19 10:16 ` Swap Dan Maas
2001-11-18 21:12 Swap war
2001-11-18 21:25 ` Swap James A Sutherland
2001-11-18 21:28 ` Swap war
2001-11-18 21:42 ` Swap François Cami
2001-11-18 21:45 ` Swap war
2001-11-18 23:03 ` Swap Erik Gustavsson
2001-11-19 18:12 ` Swap Eric W. Biederman
2001-11-19 18:43 ` Swap Rik van Riel
2001-11-20 2:49 ` Swap Eric W. Biederman
2001-11-20 3:33 ` Swap Ryan Cumming
2001-11-20 11:43 ` Swap Rik van Riel
2001-11-20 11:41 ` Swap Rik van Riel
2001-11-19 19:12 ` Swap James A Sutherland
2001-11-20 2:47 ` Swap Eric W. Biederman
2001-11-20 9:16 ` Swap James A Sutherland
2001-11-18 22:05 ` Swap J.A. Magallon
2001-11-18 22:21 ` Swap François Cami
2001-11-18 22:36 ` Swap Charles Marslett
2001-11-18 22:54 ` Swap J.A. Magallon
2001-11-18 23:36 ` Swap Bernd Eckenfels
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