Re: wrong in_flight diskstat in 2.6.16.1

[Martin Devera <devik@cdi.cz>]

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).
thanks, Martin
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