Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751092AbaKPUoz (ORCPT ); Sun, 16 Nov 2014 15:44:55 -0500 Received: from mail-yh0-f50.google.com ([209.85.213.50]:59643 "EHLO mail-yh0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbaKPUox (ORCPT ); Sun, 16 Nov 2014 15:44:53 -0500 MIME-Version: 1.0 In-Reply-To: References: Date: Mon, 17 Nov 2014 02:14:52 +0530 Message-ID: Subject: Re: read performance is too low compared to write - /dev/sda1 From: Jagan Teki To: Roger Heflin Cc: Tejun Heo , davem , linux-ide , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14 November 2014 19:22, Roger Heflin wrote: > What kind of underlying disk is it? GEN3 Sata link, SSD from Samsung. > > 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. -- 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/