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Message-ID: <20091112210000.GO8742@kernel.dk> Date: Thu, 12 Nov 2009 22:00:01 +0100 From: Jens Axboe <jens.axboe@...cle.com> To: Jeff Moyer <jmoyer@...hat.com> Cc: Jan Kara <jack@...e.cz>, 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 On Thu, Nov 12 2009, Jeff Moyer wrote: > 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. cat /sys/block/<dev>/device/queue_depth :-) -- Jens Axboe -- 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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