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Date: Thu, 12 Nov 2009 15:44:02 -0500 From: Jeff Moyer <jmoyer@...hat.com> To: Jan Kara <jack@...e.cz> Cc: jens.axboe@...cle.com, LKML <linux-kernel@...r.kernel.org>, Chris Mason <chris.mason@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, Mike Galbraith <efault@....de>, mszeredi@...e.de Subject: Re: Performance regression in IO scheduler still there Jan Kara <jack@...e.cz> writes: > On Wed 11-11-09 12:43:30, Jeff Moyer wrote: >> Jan Kara <jack@...e.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? > I don't think I am. How do I find out? Good question. ;-) I grep for NCQ in dmesg output and make sure it's greater than 0/32. There may be a better way, though. >> 2.6.29 2.6.32-rc6,low_latency=0 >> ---------------------------------- >> Average: 34.6648 34.4475 >> Pop.Std.Dev.: 0.55523 0.21981 > Hmm, strange. Miklos Szeredi tried tiobench on his machine and he also > saw the regression. I'll try to think what could make the difference. OK, I'll try again. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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