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From: Badari Pulavarty <pbadari@us.ibm.com>
To: Andrew Morton <akpm@digeo.com>
Subject: Re: More Testing with 4000 disks
Date: Mon, 7 Apr 2003 14:32:08 -0800
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On Monday 07 April 2003 02:15 pm, Andrew Morton wrote:
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
> > Hi,
> >
> > Here is more on testing with simulated 4000 disks.
> >
> > I mounted 4000 simulated (scsi_debug) disks. But
> > when I tried to do IO on 200 of them (just reads),
> > system is 100% busy. Here are the vmstat,
> > 10-sec profile output and sysrq-t output.
> >
> > I am wondering why 100% sys ?
>
> This doesn't make sense.  You're showing 50% CPU time in schedule(), yet
> the (undescribed) machine is doing only 11k context switches/sec.

Machine is:
8x 900MHz P-III
4GB RAM

>
> How come?
>
> What context switch rate and profile were you getting when performing IO
> against a large number of real disks?

I have only 50 real disks. I can get info on these.

Thanks,
Badari