Re: [BENCHMARK] max bomb segment tuning with read latency 2 patch in contest

Andrew Morton
2002-12-07T06:07:19Z

Con Kolivas wrote:
>
> ...
> >If the SMP machine is using scsi then that tends to make the elevator
> >changes less effective. Because the disk sort-of has its own internal
> >elevator which in my testing on a Fujitsu disk has the same ill-advised
> >design as the kernel's elevator: it treats reads and writes in a similar
> >manner.
>
> These are ide disks, in the same format as those used in the UP machine, so it
> still should be showing the same effect? I think higher numbers in UP would
> increase the resolution more for these results - apart from that is there any
> disadvantage to doing it in SMP? If you think it's worth running them in UP
> mode I'll do that.

Oh, OK. I was guessing, and guessed wrong. No, I don't expect you'd
see much difference switching to UP for those tests which are sensitive
to the IO scheduler policy.