Re: PATCH against 2.2.13: disk io stats in /proc/stat
Martin Dalecki (dalecki@cs.net.pl)
Thu, 23 Dec 1999 19:09:32 +0100
arijort@valinux.com wrote:
>
> I was looking around for a utility to give me some
> stats on my disk io. Something like iostat in Solaris.
>
> Well, I found that /proc/stat only reports stats
> for 4 disks. I'm not sure why that limitation exists,
> but then I learned from Ted T'so that /proc/stat
> is problematic in other ways.
>
> A kernel instance only maintains a single
> struct kernel_stat and thus io's into the indexed
> dk_drive_rio, for instance are differentiated by
> device. Io's to /dev/hda1 and /dev/sda1 are
> comingled, and thus corrupted. At least that's
> how I'm reading this code.
>
> I made up this one patch which I believe ups the
> number of devices reported in /proc/stat to 16.
> But the problem of the undifferentiated devices
> is a larger fish. Could we break up the indices
> for io stats in kernel_stat into categories pertaining
> to device types?
>
/proc/stat should be killed asap. There should a counter in
the device strcut for this purpose an an reserver ioctrl on
the device special file to get this data.
--
Marcin Dalecki
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