Re: Performance regression in IO scheduler still there

Jeff Moyer
2009-11-11T17:44:05Z

Jan Kara <jack@suse.cz> writes:

> Sadly, I don't see the improvement you can see :(. The numbers are the
> same regardless low_latency set to 0:
> 2.6.32-rc5 low_latency = 0:
> 37.39 36.43 36.51 -> 36.776667 0.434920
> But my testing environment is a plain SATA drive so that probably
> explains the difference...

I just retested (10 runs for each kernel) on a SATA disk with no NCQ
support and I could not see a difference. I'll try to dig up a disk
that support NCQ. Is that what you're using for testing?

Cheers,
Jeff

2.6.29 2.6.32-rc6,low_latency=0
----------------------------------
Average: 34.6648 34.4475
Pop.Std.Dev.: 0.55523 0.21981