From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viji V Nair Subject: Re: optimising filesystem for many small files Date: Sat, 17 Oct 2009 23:26:04 +0530 Message-ID: <84c89ac10910171056i773dfb93wc2e917a086dd8ef0@mail.gmail.com> References: <84c89ac10910162352x5cdeca37icfbf0af2f2325d7c@mail.gmail.com> <4AD9D599.3000306@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: ext3-users@redhat.com, linux-ext4@vger.kernel.org To: Eric Sandeen Return-path: Received: from mail-px0-f171.google.com ([209.85.216.171]:56645 "EHLO mail-px0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469AbZJQR4A convert rfc822-to-8bit (ORCPT ); Sat, 17 Oct 2009 13:56:00 -0400 Received: by pxi1 with SMTP id 1so246181pxi.33 for ; Sat, 17 Oct 2009 10:56:04 -0700 (PDT) In-Reply-To: <4AD9D599.3000306@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: these files are not in a single directory, this is a pyramid structure. There are total 15 pyramids and coming down from top to bottom the sub directories and files are multiplied by a factor of 4. The IO is scattered all over!!!! and this is a single disk file system. Since the python application is creating files, it is creating multiple files to multiple sub directories at a time. On Sat, Oct 17, 2009 at 8:02 PM, Eric Sandeen wrot= e: > Viji V Nair wrote: >> >> Hi, >> >> System : Fedora 11 x86_64 >> Current Filesystem: 150G ext4 (formatted with "-T small" option) >> Number of files: 50 Million, 1 to 30K png images >> >> We are generating these files using a python programme and getting v= ery >> slow IO performance. While generation there in only write, no read. = After >> generation there is heavy read and no write. >> >> I am looking for best practices/recommendation to get a better >> performance. >> >> Any suggestions of the above are greatly appreciated. >> >> Viji >> > > I would start with using blktrace and/or seekwatcher to see what your= IO > patterns look like when you're populating the disk; I would guess tha= t > you're seeing IO scattered all over. > > How you are placing the files in subdirectories will affect this quit= e a > lot; sitting in 1 directory for a while, filling with images, before = moving > on to the next directory, will probably help. =A0Putting each new fil= e in a > new subdirectory will probably give very bad results. > > -Eric > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html