Messages in this thread | | | Subject | Re: disk statistics issue in 2.6.27 | From | Miquel van Smoorenburg <> | Date | Thu, 23 Oct 2008 18:05:02 +0200 |
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On Wed, 2008-10-22 at 19:17 +0200, Jens Axboe wrote: > On Wed, Oct 22 2008, Miquel van Smoorenburg wrote: > > On Mon, 2008-10-20 at 19:12 +0200, Jens Axboe wrote: > > > On Sun, Oct 19 2008, Miquel van Smoorenburg wrote: > > > > > I noticed that the "iostat -k -x 2" output does't make any sense. > > > > The number of reads/sec and number of writes/sec are about what I > > > > would expect, and so are the other fields, but rkB/sec and wkB/sec > > > > are completely off-scale: gigabytes read/written per second. > > > > > > > > Are the reported values in iostat any sort of multiple of the real > > > throughtput, or is is just insanely large? > > > > It looks like it's a multiple, but it appears to vary between 128 and > > 512, and is different for reads and writes, so I do not know what to > > make of it. > >
I added some debug statements to block/blk-core.c, and it appears that blk_end_io() is always called with nr_bytes == 16320 Kbytes (16711680).
Ofcourse I should have noticed earlier that iostat -x 2 always prints 32640 as "average request size" (in sectors).
Mike.
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