From: Kernel Panic <cinap_lenrek@gmx.de>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] 8 cores
Date: Thu, 17 Jul 2008 12:04:07 +0200 [thread overview]
Message-ID: <487F1917.9060406@gmx.de> (raw)
In-Reply-To: <2125ed224c77c85fc13d81eb95377a2a@terzarima.net>
Charles Forsyth wrote:
>> I could imagine that databases use mmap() havily
>>
>
> it's a little mystery for me why they would do that since it's slower (or ought to be),
> because the trap path and fault recovery must do more work than syscall (perhaps much more).
> it's also difficult then to optimise the replacement strategy for the application
> without madvise calls (and you trust those implicitly?) but those are system calls that cost time.
>
>
makes sense of course...
but at least mysql uses mmap() for some table types as a caching mechanism.
http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/
this may just be an exception and real databases use read()/write() syscalls
and implement the caching themself.
but where should i know... i dont need/use databases and have not looked
at the sourcecode of one.
cinap
next prev parent reply other threads:[~2008-07-17 10:04 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-15 22:28 erik quanstrom
2008-07-15 22:27 ` Benjamin Huntsman
2008-07-15 22:35 ` Williams, Mitch
2008-07-16 1:39 ` erik quanstrom
2008-07-16 5:12 ` Benjamin Huntsman
2008-07-16 7:00 ` sqweek
2008-07-16 12:54 ` Russ Cox
2008-07-16 11:37 ` C H Forsyth
2008-07-16 12:13 ` John Waters
2008-07-16 13:03 ` a
2008-07-16 13:44 ` Uriel
2008-07-16 13:55 ` John Waters
2008-07-16 14:16 ` Robert William Fuller
2008-07-16 13:07 ` erik quanstrom
2008-07-16 13:42 ` Uriel
2008-07-16 15:02 ` Benjamin Huntsman
2008-07-16 18:56 ` Uriel
2008-07-17 7:59 ` Kernel Panic
2008-07-17 9:07 ` Charles Forsyth
2008-07-17 10:04 ` Kernel Panic [this message]
2008-07-17 10:14 ` Roman V. Shaposhnik
2008-07-17 12:55 ` ron minnich
2008-07-17 12:58 ` William Josephson
2008-07-17 13:45 ` erik quanstrom
2008-07-17 14:11 ` ron minnich
2008-07-17 14:32 ` Roman V. Shaposhnik
2008-07-17 13:32 ` Paweł Lasek
2008-07-17 14:07 ` Kernel Panic
2008-07-16 22:44 ` Iruata Souza
2008-07-17 8:38 ` Kernel Panic
2008-07-17 18:14 ` Iruata Souza
2008-07-23 11:42 ` matt
2008-07-23 18:32 ` Iruata Souza
2008-07-16 1:41 ` andrey mirtchovski
2008-07-16 20:38 ` Roman V. Shaposhnik
2008-07-17 2:09 ` erik quanstrom
2008-07-17 10:18 ` Roman V. Shaposhnik
2008-07-17 12:41 erik quanstrom
2008-07-17 12:56 ` William Josephson
2008-07-17 12:58 ` ron minnich
2008-07-17 13:46 ` erik quanstrom
2008-07-17 14:06 ` ron minnich
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