From: "Jeffrey W. Baker" <jwbaker@acm.org>
To: linux-kernel@vger.kernel.org
Subject: Re: 2.4.17: pwrite destroys block I/O throughput
Date: 30 Jan 2002 15:35:53 -0800 [thread overview]
Message-ID: <1012433753.17074.15.camel@heat> (raw)
In-Reply-To: <1012431302.17074.10.camel@heat>
In-Reply-To: <1012431302.17074.10.camel@heat>
On Wed, 2002-01-30 at 14:55, Jeffrey W. Baker wrote:
> Hi there,
>
> I've never heard of pwrite and pread before, but htdig apparently makes
> very heavy use of it. On my 2.4.17 SMP 2GB HIGHMEM + ext3 system,
> running htdig destroys input rates for every other process. htdig's
> output proceeds at approximately 2MB/s, but input for the entire system
> runs only at about 4KB/s (YES, KB!). If I suspend htdig, system block
> input increases to the normal rate of 10-50MB/s. Output still works, as
> a dd from /dev/zero to a 400MB file runs at about 25MB/s.
I looked around a little more and it seems that htdig is doing SYNC I/O
on its db2 files. This may be the problem. If so, it seems that sync
I/O is able to DoS all other I/O consumers on the machine.
-jwb
prev parent reply other threads:[~2002-01-30 23:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-30 22:55 2.4.17: pwrite destroys block I/O throughput Jeffrey W. Baker
2002-01-30 23:24 ` Andreas Dilger
2002-01-30 23:27 ` Andrew Morton
2002-01-30 23:35 ` Jeffrey W. Baker [this message]
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