From: "Stephen C. Tweedie" <sct@redhat.com>
To: Steven Cole <elenstev@mesatop.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>,
Andrew Morton <akpm@zip.com.au>,
linux-kernel@vger.kernel.org, Steven Cole <scole@lanl.gov>
Subject: Re: 2.5.28, dbench results with ext3 significantly lower than with ext2.
Date: Fri, 26 Jul 2002 19:55:28 +0100 [thread overview]
Message-ID: <20020726195528.B2299@redhat.com> (raw)
In-Reply-To: <1027701923.3148.10.camel@spc9.esa.lanl.gov>; from elenstev@mesatop.com on Fri, Jul 26, 2002 at 10:45:23AM -0600
Hi,
On Fri, Jul 26, 2002 at 10:45:23AM -0600, Steven Cole wrote:
> I found that dbench gives significantly lower numbers when
> the partition on which it is run is mounted as ext3.
Yes, especially with ext3 using its default 5-second commit intervals
and ext2 using 30 second timeouts for its own bdflush.
dbench does a lot of IO to temporary files, writing large amounts of
data and then shortly deleting it. If it can run fast enough to
delete the data before it hits disk, it goes _much_ faster, so you end
up measuring cache speed and not disk speed. ext3 is particulary hurt
by that given its shorted default commit timeouts.
Cheers,
Stephen
next prev parent reply other threads:[~2002-07-26 18:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-26 16:45 2.5.28, dbench results with ext3 significantly lower than with ext2 Steven Cole
2002-07-26 18:55 ` Stephen C. Tweedie [this message]
2002-07-26 18:56 ` Andrew Morton
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