Re: Direct io on block device has performance regression on 2.6.xkernel
From: Andrew Morton
Date: Wed Mar 09 2005 - 15:14:56 EST
"Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx> wrote:
> Andrew Morton wrote on Tuesday, March 08, 2005 10:28 PM
> > But before doing anything else, please bench this on real hardware,
> > see if it is worth pursuing.
> Let me answer the questions in reverse order. We started with running
> industry standard transaction processing database benchmark on 2.6 kernel,
> on real hardware (4P smp, 64 GB memory, 450 disks) running industry
> standard db application. What we measured is that with best tuning done
> to the system, 2.6 kernel has a huge performance regression relative to
> its predecessor 2.4 kernel (a kernel from RHEL3, 2.4.21 based).
That's news to me. I thought we were doing OK with big database stuff.
Surely lots of people have been testing such things.
> And yes, it is all worth pursuing, the two patches on raw device recuperate
> 1/3 of the total benchmark performance regression.
On a real disk driver? hm, I'm wrong then.
Did you generate a kernel profile?
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/