From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: Slow perfs with IDE SSD Date: Thu, 13 Jul 2006 01:21:22 +0900 Message-ID: <44B52182.3020008@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from nz-out-0102.google.com ([64.233.162.196]:5269 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S1750775AbWGLQUT (ORCPT ); Wed, 12 Jul 2006 12:20:19 -0400 Received: by nz-out-0102.google.com with SMTP id l1so164068nzf for ; Wed, 12 Jul 2006 09:20:18 -0700 (PDT) In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: =?UTF-8?B?RnJhbsOnb2lzLUp1bGllbiBNYXJiYXVk?= Cc: linux-ide@vger.kernel.org =46ran=C3=A7ois-Julien Marbaud wrote: > Hi ! >=20 > I'm doing an internship in a research lab, and we are trying to use a= P.ATA SSD > in order to speed-up a genome computation software. >=20 > We got a performance problem, expecially with access time : access ti= me is about > 800us, and according to the manufacturer it should be about 40us. The= bandwith > is OK. >=20 > The SSD is a 2.5' flash hard drive, the slave of the first IDE channe= l. >=20 > We wonder if that could be the because P.ATA driver is not really don= e for small > access times, so we got such a poor time. In that case, I guess we wo= uld have to > have a closer look at the driver ...=20 =46irst of all, try noop elevator. echo noop > /sys/block/hdx/queue/scheduler Depending on your workload, adjusting plugging delay/threshold=20 parameters might help. These are initialized in the kernel source file= =20 block/ll_rw_blk.c::blk_queue_make_request(). q->unplug_thresh and=20 q->unplug_delay. --=20 tejun