Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965530AbaKNNU4 (ORCPT ); Fri, 14 Nov 2014 08:20:56 -0500 Received: from mail-yk0-f181.google.com ([209.85.160.181]:60915 "EHLO mail-yk0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964865AbaKNNUy (ORCPT ); Fri, 14 Nov 2014 08:20:54 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Roger Heflin Date: Fri, 14 Nov 2014 07:20:33 -0600 Message-ID: Subject: Re: read performance is too low compared to write - /dev/sda1 To: Jagan Teki Cc: Tejun Heo , davem@davemloft.net, linux-ide , "linux-kernel@vger.kernel.org" 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 If you are robocoping small files you will hit other limits. Best I have seen with small files is around 30 files/second, and that involves multiple copies going on. Remember with a small files there are several reads and writes that need to be done to complete a create of a small file and each of these take time. 30 files/second ~ 30ms per file, not that bad considering that on a real spinning disk a single read/write op is 5-10ms, and creating the file entry, copying data and closing the file takes several operations (at least create file entry, write small amount of data, update file entry date/time/info). If the write in the middle is not a significant amount of data, the 2 extra ops are what hurts. On Fri, Nov 14, 2014 at 6:55 AM, Jagan Teki wrote: > Hi, > > I'm doing a performance testing on my bench ARM box. > > 1. dd test: I have validate the read and write by mounting /dev/sda1 > with ext4 filesystem, > able to get the good performance numbers where read is high > compared to write > > 2. robocopy test: > - mkfs.ext4 /dev/sda1 > - mount /dev/sda1 /media/disk > - << configured samba >> > - Mapped the /media/disk on windows > - login on the mapped driver in windows > - did a robocopy test, where write got 84MBps and read 14MBps > > read performance is too slow when compared to write in robocopy case. > Can anyone help me out, how to debug this further. > > thanks! > -- > Jagan. > -- > 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/ -- 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/