Re: More Testing with 4000 disks

[Andrew Morton]

Badari Pulavarty <[e-mail]> 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.

How come?

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