Re: ios_in_flight of CONFIG_BLK_STATS (still) negative in 2.4
From: Zlatko Calusic
Date: Fri Aug 18 2006 - 05:24:57 EST
Steffen Maier <smaier@xxxxxxxxxxxxxxxxxxxxx> writes:
> in this posting I would like to analyze and discuss a bug(?), that
> causes the number of I/O requests in flight (ios_in_flight) of the
> extended block device statistics (CONFIG_BLK_STATS) to become and stay
> negative on various kernels of version 2.4. In turn, this leads to
> erroneous display of 100% utilization for certain classes of harddisk
> devices with 'iostat -x' and probably other statistic tools relying on
> the 13th (last but two) field (ios_in_flight) of extended block device
> statistics listed in /proc/partitions.
> First I encountered the behavior with 2.4.24 but could reproduce it
> with 2.4.33-rc3 (which is now the latest 2.4 kernel version 2.4.33).
> There have been various postings concerning this problem in recent
> years but to the best of my knowledge no ultimate fix has been merged
> into the mainstream kernel so far.
Have you tried this patch: http://linux.inet.hr/iostat_patch_2.4.html
It was made against 2.4.24 so you'll probably need to tweak it a
little bit before applying it cleanly to a newer 2.4, but I think it
deserves it's chance.
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