Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 5 Aug 2002 09:51:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 5 Aug 2002 09:51:14 -0400 Received: from barry.mail.mindspring.net ([207.69.200.25]:58406 "EHLO barry.mail.mindspring.net") by vger.kernel.org with ESMTP id ; Mon, 5 Aug 2002 09:51:13 -0400 Message-ID: <3D4E8387.3000704@mindspring.com> Date: Mon, 05 Aug 2002 06:54:15 -0700 From: Walt H User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.1b) Gecko/20020722 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Mark Hahn Cc: linux-kernel Subject: Re: Raid0 slowdown from 2.4.19-rc1 References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2333 Lines: 68 Sorry, should have said more about raid arrays. Drives are partitioned as follows: hda1, hdc1 = 4GB hda2, hdc2 = Extended part - remainder of drive hda5, hdc5 = 2GB = raid1, md0 /boot hda6, hdc6 = ~15GB = raid0, md1 /usr hda7, hdc7 = ~15GB = raid0, md2 /home hda8, hdc8 = 1.5GB = raid0, / hda9, hdc9 = remainder = swap I agree, it seems as though you could see preempt lower performance, but again, I haven't seen that either. In fact, the 2.4.18 kernel I was using before was compiled with preempt also and showed ~68MB/Sec on md1,md2. As for changes I may have made to .config? Nothing new. 2.4.19-rc1 compiled with xfs and preempt worked well also. I tried looking for differences in raid drivers, but there were none to the raid0 driver. ide-pdc202xx.c contained many changes, but I'm not a kernel hacker and couldn't spot anything that might have affected this. Odd that it shows up even under hdparm. Interestingly, when testing with bonnie++, the overall sequential output was similar to the higher performing older kernels. However, creates, deletes, and rewrites were all down significantly. -Walt Mark Hahn wrote: >>Final 2.4.19 was patched with XFS and preempt and compiled using > > > it's easy to imagine cases where preempt would produce lower performance, > though I haven't seen any hard evidence of that. > > >>cutting out preempt patches. First md1 array consists of two partitions >>from hda & hdc. hdparm for both drives looks fine by themselves: > > > are they the first two partitions in hda/c? > > >>/dev/hda: >> Timing buffered disk reads: 64 MB in 1.66 seconds = 38.55 MB/sec >>/dev/hdc: >> Timing buffered disk reads: 64 MB in 1.65 seconds = 38.79 MB/sec > > > such a disk will normally degrade to around half that performance > in the tail of the disk. > > >>/dev/md1: >> Timing buffered disk reads: 64 MB in 1.44 seconds = 44.44 MB/sec >> >>In 2.4.18 and up through 2.4.19-rc1 I saw 66-70MB/sec from this array. >>Starting in rc2 it dropped to the mid 40's. I've also ran bonnie++ and > > > nothing else changed? > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/