Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965570AbaKNNxW (ORCPT ); Fri, 14 Nov 2014 08:53:22 -0500 Received: from mail-yk0-f173.google.com ([209.85.160.173]:39410 "EHLO mail-yk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965331AbaKNNxU (ORCPT ); Fri, 14 Nov 2014 08:53:20 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Roger Heflin Date: Fri, 14 Nov 2014 07:52:59 -0600 Message-ID: Subject: Re: read performance is too low compared to write - /dev/sda1 To: Jagan Teki Cc: Tejun Heo , davem , 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 What kind of underlying disk is it? On Fri, Nov 14, 2014 at 7:36 AM, Jagan Teki wrote: > On 14 November 2014 18:50, Roger Heflin wrote: >> 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. >> > > But, I tried 4gb and 1gb files both got a similar numbers. > >> 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/