From: "Ray Lee" <ray-lk@madrabbit.org>
To: "Tommy Vercetti" <vercetti@zlew.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.21.1 - 97% wait time on IDE operations
Date: Sat, 26 May 2007 08:13:06 -0700 [thread overview]
Message-ID: <2c0942db0705260813g6aeedbfepc0afa94ba3550e5b@mail.gmail.com> (raw)
In-Reply-To: <200705261505.38109@gj-laptop>
On 5/26/07, Tommy Vercetti <vercetti@zlew.org> wrote:
> I was trying to get answer to my question around, but no one knows.
> I do have DMA turned on, etc, yet - on extensive harddrive operations wait
You may have DMA turned on, but it may be ineffectual if you don't
have the right IDE driver handing your disk.
> time is 90+% , which means that machine is waiting, rather than doing
> something meanwhile. (I guess).
What does hdparm -tT /dev/hda say? If the numbers are reasonable
(~400MB/s for cache reads, ~25MB/s for buffered disk reads), then
you're just doing a lot of seeking on the drive, and that takes a long
time. (Drives can seek about 100 times a second. If every seek reads
only 4k of data, that's 400k of data processed per second, or a lot of
time spent with the CPU waiting on I/O.)
next prev parent reply other threads:[~2007-05-26 15:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-26 13:05 Tommy Vercetti
2007-05-26 13:52 ` Paolo Ornati
2007-05-26 14:07 ` Tommy Vercetti
2007-05-26 15:56 ` Paolo Ornati
2007-05-26 14:39 ` Julio M. Merino Vidal
2007-05-26 15:13 ` Ray Lee [this message]
2007-05-26 15:46 ` Tommy Vercetti
2007-05-26 16:07 ` Ray Lee
2007-05-27 10:22 ` Tommy Vercetti
2007-05-27 12:02 ` Alan Cox
2007-05-27 18:17 ` Clemens Koller
2007-05-28 9:51 ` Benny Amorsen
2007-05-28 19:22 ` Alan Cox
2007-05-26 15:23 ` Guillaume Chazarain
2007-05-29 20:32 ` Bill Davidsen
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