Messages in this thread | | | Date | Tue, 23 May 2006 11:47:48 +0200 | From | Jens Axboe <> | Subject | Re: wrong in_flight diskstat in 2.6.16.1 |
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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
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