From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Tue, 05 Jun 2007 16:15:18 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l55NFDWt009150 for ; Tue, 5 Jun 2007 16:15:14 -0700 Message-ID: <4665EF04.5020803@sgi.com> Date: Wed, 06 Jun 2007 09:17:24 +1000 From: Vlad Apostolov MIME-Version: 1.0 Subject: Re: Reducing memory requirements for high extent xfs files References: <200705301649.l4UGnckA027406@oss.sgi.com> <20070530225516.GB85884050@sgi.com> <4665E276.9020406@agami.com> <4665ED89.4090202@sgi.com> In-Reply-To: <4665ED89.4090202@sgi.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Vlad Apostolov Cc: Michael Nishimoto , David Chinner , Michael Nishimoto , xfs@oss.sgi.com Vlad Apostolov wrote: > Michael Nishimoto wrote: >> >> >> David Chinner wrote: >>> On Wed, May 30, 2007 at 09:49:38AM -0700, Michael Nishimoto wrote: >>> > Hello, >>> > >>> > Has anyone done any work or had thoughts on changes required >>> > to reduce the total memory footprint of high extent xfs files? >>> >>> We changed the way we do memory allocation to avoid needing >>> large contiguous chunks of memory a bit over a year ago; >>> that solved the main OOM problem we were getting reported >>> with highly fragmented files. >>> >>> > Obviously, it is important to reduce fragmentation as files >>> > are generated and to regularly defrag files, but both of these >>> > alternatives are not complete solutions. >>> > >>> > To reduce memory consumption, xfs could bring in extents >>> > from disk as needed (or just before needed) and could free >>> > up mappings when certain extent ranges have not been recently >>> > accessed. A solution should become more aggressive about >>> > reclaiming extent mapping memory as free memory becomes limited. >>> >>> Yes, it could, but that's a pretty major overhaul of the extent >>> interface which currently assumes everywhere that the entire >>> extent tree is in core. >>> >>> Can you describe the problem you are seeing that leads you to >>> ask this question? What's the problem you need to solve? >>> >>> Cheers, >>> >>> Dave. >>> -- >>> Dave Chinner >>> Principal Engineer >>> SGI Australian Software Group >> >> I realize that this work won't be trivial which is why I asked if anyone >> has thought about all relevant issues. >> >> When using NFS over XFS, slowly growing files (can be ascii log files) >> tend to fragment quite a bit. One system had several hundred files >> which required more than one page to store the extents. Quite a few >> files had extent counts greater than 10k, and one file had 120k extents. >> Besides the memory consumption, latency to return the first byte of the >> file can get noticeable. >> >> Michael >> > Hi Michael, > > You could use XFS_XFLAG_EXTSIZE and XFS_XFLAG_RTINHERIT flags to > set extent hint size, which would reduce the file fragmentation in > this scenario. > Please check xfcntl man page for more details. > > Regards, > Vlad I meant XFS_XFLAG_EXTSZINHERIT not XFS_XFLAG_RTINHERIT. This one should be set on a parent directory. Regards, Vlad