From: Jeff Dike <jdike@addtoit.com>
To: Chris Lightfoot <chris@ex-parrot.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] UBD performance
Date: Mon, 10 Oct 2005 10:38:03 -0400 [thread overview]
Message-ID: <20051010143803.GB3448@ccure.user-mode-linux.org> (raw)
In-Reply-To: <0sFQ9zs1eorU.3hmKqEgWHCfEJIJucfz6wA@sphinx.mythic-beasts.com>
On Mon, Oct 10, 2005 at 10:10:24AM +0100, Chris Lightfoot wrote:
> OK. The host is indeed using a 4K block filesystem; I
> couldn't find your O_DIRECT patch, but turning on O_DIRECT
> with fcntl just after opening the backing file gives these
> results:
> http://ex-parrot.com/~chris/tmp/20051010/host-vs-uml-io-results-3.png
> i.e., the AIO implementation is now slower than the stock
> implementation for writes of size up to about 8KB, but
> faster for larger writes; it's still quite a bit slower
> than the host.
There aren't very good labels on that graph, but it looks consistent with my
experience, which is 25-30% faster kernel builds with AIO/O_DIRECT.
The next question is where the slowdown is happening.
Jeff
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next prev parent reply other threads:[~2005-10-10 14:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-08 16:32 [uml-devel] UBD performance Chris Lightfoot
2005-10-09 8:49 ` [uml-devel] " Chris Lightfoot
2005-10-09 18:45 ` [uml-devel] " Jeff Dike
2005-10-09 22:51 ` Chris Lightfoot
2005-10-10 1:35 ` Jeff Dike
2005-10-10 9:10 ` Chris Lightfoot
2005-10-10 14:38 ` Jeff Dike [this message]
2005-10-10 15:44 ` Chris Lightfoot
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