Re: iozone write 50% regression in kernel 2.6.24-rc1

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Mon, 2007-11-12 at 10:14 +0800, Zhang, Yanmin wrote:

> > Subject: mm: speed up writeback ramp-up on clean systems
>
> I tested kernel 2.6.23, 2,6,24-rc2, 2.6.24-rc2_peter(2.6.24-rc2+this patch).
> 
> 1) Compare among first/second/following running
> 2.6.23: second run of iozone will get about 28% improvement than first run.
> 	Following run is very stable like 2nd run.
> 2.6.24-rc2: second run of iozone will get about 170% improvement than first run. 3rd run
> 	will get about 80% improvement than 2nd. Following run is very stable like 3rd run.
> 2.6.24-rc2_peter: second run of iozone will get about 14% improvement than first run. Following
> 	run is mostly stable like 2nd run.
> So the new patch really improves the first run result. Comparing wiht 2.6.24-rc2, 2.6.24-rc2_peter
> has 330% improvement on the first run.
> 
> 2) Compare among different kernels(based on the stable highest result):
> 2.6.24-rc2 has about 50% regression than 2.6.23.
> 2.6.24-rc2_peter has the same result like 2.6.24-rc2.
>
> From this point of view, above patch has no improvement. :)

Drad, still good test results though.

Could you describe you system in detail, that is, you have 8GB of memory
and 8 cpus (2*quad?). How many disks does it have and are those
aggregated using md or dm? What filesystem do you use?

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