From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 8C7FC7F4E for ; Sun, 26 Oct 2014 17:18:50 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id 4B293304048 for ; Sun, 26 Oct 2014 15:18:50 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id 5SnwDmnnBpapLSWt (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Sun, 26 Oct 2014 15:18:45 -0700 (PDT) Date: Sun, 26 Oct 2014 18:18:11 -0400 From: Brian Foster Subject: Re: file streams allocator behavior Message-ID: <20141026221811.GA13113@bfoster.bfoster> References: <544BF26F.6000708@clear.net.nz> <544C159E.8010408@hardwarefreak.com> <20141026142559.GA61711@bfoster.bfoster> <544D2EE1.3080304@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <544D2EE1.3080304@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Stan Hoeppner Cc: Richard Scobie , xfs@oss.sgi.com On Sun, Oct 26, 2014 at 12:26:57PM -0500, Stan Hoeppner wrote: > > > On 10/26/2014 09:26 AM, Brian Foster wrote: > > On Sat, Oct 25, 2014 at 04:26:54PM -0500, Stan Hoeppner wrote: > >> On 10/25/2014 01:56 PM, Richard Scobie wrote: > >>> Stan Hoeppner said: > >>> > >>>> How can I disable or change the filestreams behavior so all files go > >>>> into the one AG for the single directory test? > >>> > >>> Hi Stan, > >>> > >>> Instead of mounting with -o filestreams, would using the chattr flag > >>> instead help? > >>> > >>> See > >>> http://xfs.org/docs/xfsdocs-xml-dev/XFS_User_Guide/tmp/en-US/html/ch06s16.html > >> > >> That won't help. That turns it on (if it's not enabled by default these > >> days). I need to turn off the behavior I'm seeing, whether it's due to > >> the filestreams allocator or default inode64. Then again it may not be > >> possible to turn it off... > >> > >> Anyone have other ideas on how to accomplish my goal? Parallel writes > >> to a single AG on the outer platter edge vs the same to all AGs across > >> the entire platter? I'm simply trying to demonstrate the differences in > >> aggregate bandwidth due to the extra seek latency of all AGs case. > >> > > > > What about just preallocating the files? Obviously this removes block > > allocation contention from your experiment, but it's not clear if that's > > relevant to your test. If I create a smaller, but analogous fs to yours, > > I seem to get this behavior from just doing an fallocate of each file in > > advance. > > > > E.g., Create directory 0, fallocate 44 files all of which end up in AG > > 0. Create directory 1, fallocate 44 files which end up in AG 1, etc. > > From there you can do direct I/O overwrites to 44 files across each AG > > or 44 files in any single AG. > > I figured preallocating would get me what I want but I've never used > fallocate, nor dd into fallocated files. Is there anything special > required here with dd, or can I simply specify the filename to dd, and > make sure bs + count doesn't go beyond EOF? > Ah, yeah. dd will truncate the file by default iirc, which would free the preallocated blocks and start from scratch. Specify 'conv=notrunc' as part of the command line to get around that. Brian > Thanks, > Stan > _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs