From: Albert Cahalan <albert@users.sf.net>
To: linux-kernel mailing list <linux-kernel@vger.kernel.org>
Cc: alandpearson@yahoo.com
Subject: Re: Huge iowait on 2.6.4 - not on 2.4.20 !
Date: 16 Apr 2004 11:12:47 -0400 [thread overview]
Message-ID: <1082128366.849.60.camel@cube> (raw)
alan pearson writes:
> On 2.6 the iowait jumps to around 70%, while 2.4 on
> both tests it is firmly zero.
The 2.4 kernel lumps iowait into idle, so you
won't see iowait on a 2.4 kernel.
> On disk read, I'm loosing 30 Mb/sec of bandwidth PER
> DISK, compared to 2.4.20.
> I've tried using both the deadline and as ioschedulers
> but no difference.
>
>
> Under real conditions (ie our application running
> which reads from all the disks simultaneously) on
> 2.6.4, the system performance is around 1/3 of 2.4.20)
>
> Summary MB/Sec :
>
> dd if=x dd if=/dev/zero
> 2.4 64 35.6
> 2.6 30.34 35.9
Well, that looks serious, but unfortunately you
can't tell what the iowait was on the 2.4 kernel.
Only the 2.6 kernel provides this information.
next reply other threads:[~2004-04-16 17:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-16 15:12 Albert Cahalan [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-04-16 12:48 Huge iowait on 2.6.4 - not on 2.4.20 ! alan pearson
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