Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755325Ab2HOBMs (ORCPT ); Tue, 14 Aug 2012 21:12:48 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:33765 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998Ab2HOBMq (ORCPT ); Tue, 14 Aug 2012 21:12:46 -0400 MIME-Version: 1.0 In-Reply-To: <201208150906343285670@gmail.com> References: <201208150906343285670@gmail.com> From: Andy Lutomirski Date: Tue, 14 Aug 2012 18:12:24 -0700 Message-ID: Subject: Re: O_DIRECT to md raid 6 is slow To: kedacomkernel Cc: linux-kernel , linux-raid Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2486 Lines: 62 Ubuntu's 3.2.0-27-generic. I can test on a newer kernel tomorrow. --Andy On Tue, Aug 14, 2012 at 6:07 PM, kedacomkernel wrote: > On 2012-08-15 08:49 Andy Lutomirski Wrote: >>If I do: >># dd if=/dev/zero of=/dev/md0p1 bs=8M >>then iostat -m 5 says: >> >>avg-cpu: %user %nice %system %iowait %steal %idle >> 0.00 0.00 26.88 35.27 0.00 37.85 >> >>Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn >>sdb 265.20 1.16 54.79 5 273 >>sdc 266.20 1.47 54.73 7 273 >>sdd 264.20 1.38 54.54 6 272 >>sdf 286.00 1.84 54.74 9 273 >>sde 266.60 1.04 54.75 5 273 >>sdg 265.00 1.02 54.74 5 273 >>md0 55808.00 0.00 218.00 0 1090 >> >>If I do: >># dd if=/dev/zero of=/dev/md0p1 bs=8M oflag=direct >>then iostat -m 5 says: >>avg-cpu: %user %nice %system %iowait %steal %idle >> 0.00 0.00 11.70 12.94 0.00 75.36 >> >>Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn >>sdb 831.00 8.58 30.42 42 152 >>sdc 832.80 8.05 29.99 40 149 >>sdd 832.00 9.10 29.78 45 148 >>sdf 838.40 9.11 29.72 45 148 >>sde 828.80 7.91 29.79 39 148 >>sdg 850.80 8.00 30.18 40 150 >>md0 1012.60 0.00 101.27 0 506 >> >>It looks like md isn't recognizing that I'm writing whole stripes when >>I'm in O_DIRECT mode. >> > kernel version? > >>--Andy >> >>-- >>Andy Lutomirski >>AMA Capital Management, LLC >>-- >>To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>the body of a message to majordomo@vger.kernel.org >>More majordomo info at http://vger.kernel.org/majordomo-info.html -- Andy Lutomirski AMA Capital Management, LLC -- 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/