Re: SAR (was Re: disks stats through /proc)

Tigran Aivazian (
Fri, 4 Dec 1998 15:21:40 +0000 (GMT)

Sorry, Stephen, I wrote my previous message before I read yours so I didn't know
it's already a fixed thing to go to 2.3 in its current form.

I will try to find something that you haven't done yet :)


On Fri, 4 Dec 1998, Stephen C. Tweedie wrote:

> Hi,
> On Thu, 3 Dec 1998 13:39:42 +0000 (GMT), Tigran Aivazian
> <> said:
> > IMHO, this should be done on a fine-grained (partition level) rather than
> > coarse (drive) level. There is enough information in
> > ll_rw_blk.c/add_request() to do it now but, of course, kernel_stat
> > structure will have to be seriously modified.
> > There is something frustrating about the quality and speed of Linux
> > development. I.e. the quality is too high and the speed is too high,
> > in other words, I can implement this disk stat feature, but I bet
> > someone else has already done it and is just about to release his
> > patch to Linus soon...
> Yep, done that. :)
> I have patches for 2.0.34/35 and 2.1.125 already working, outputing
> both per-partition and per-spindle access stats via /proc/partitions.
> A "sard" front-end gives human-readable output. (It is modeled on the
> output of the SVR4 "sar -d" output.)
> Currently you get average %utilisation; average request queue length;
> number of K transfered plus number of distinct IOs for reads, writes
> and combined; and average request service time for each disk and each
> partition.
> Look for
> for the patches and sard source code. The plan is to integrate this
> into 2.3 once we have got a more sensible kdev_t in the kernel.
> --Stephen

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