From: Jens Axboe <axboe@suse.de>
To: Martin Devera <devik@cdi.cz>
Cc: linux-kernel@vger.kernel.org
Subject: Re: wrong in_flight diskstat in 2.6.16.1
Date: Tue, 23 May 2006 11:47:48 +0200 [thread overview]
Message-ID: <20060523094748.GR26261@suse.de> (raw)
In-Reply-To: <4472D651.5010206@cdi.cz>
On Tue, May 23 2006, Martin Devera wrote:
> Jens Axboe wrote:
> >On Tue, May 23 2006, Martin Devera wrote:
> >>Hello,
> >>
> >>I see weird output from /sys/block/sd{a,b}/stat on our AMD64-X2 smp
> >>machine with HT1000 (Broadcom) SATA with 2 WD 250GB HDDs in MD raid1. AS
> >>scheduler was used, change to noop didn't change anything. It is vanilla
> >>2.6.16.1 and here are absolute values in hex and one second differences
> >>below:
> >>
> >>132CDF 56D62 61753C0 6966BC 165A8EB 5FF5B6C 3B32D6C0 1110594C FFCA89A4
> >>FEE85878 49FF74E4
> >>132CDF 56D62 61753C0 6966BC 165A8EF 5FF5B6C 3B32D6E0 111059D0 FFCA89A1
> >>FEE85C60 79291244
> >> 0: 0
> >> 1: 0
> >> 2: 0
> >> 3: 0
> >> 4: 4
> >> 5: 0
> >> 6: 32
> >> 7: 132
> >> 8: -3
> >> 9: 1000
> >>10: 791256416
> >>
> >>As you can see in_flight is constantly negative and it is DECREASING
> >>slowly all the time.
> >>I can't find any reason for it :-\
> >
> >Are you using io barriers?
> >
> >[PATCH] blk: fix gendisk->in_flight accounting during barrier sequence
>
> I don't think so, I just used
> mount / -o remount,barrier=0
> to make it sure and it keeps decrementing. I'll however apply the patch
> (and others up to 2.6.16.18) at night (I'm not allowed to restart the
> machine just now).
Ah, but you are using md, which uses barriers for superblock updates. So
the patch will likely help you.
--
Jens Axboe
prev parent reply other threads:[~2006-05-23 9:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-23 8:52 wrong in_flight diskstat in 2.6.16.1 Martin Devera
2006-05-23 9:23 ` Jens Axboe
2006-05-23 9:30 ` Martin Devera
2006-05-23 9:47 ` Jens Axboe [this message]
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