Hey Christian, On Fri, May 17, 2013 at 05:02:21AM -0700, Christian Kujau wrote: > a while ago I was setting & reading extended attributes to ~25000 files > in a directory structure on an XFS filesystem. The files were usually a > few MB in size, but some where up to 2GB in size. > > Anyway, I *felt* that setting or reading these xattrs was going very > slowly. While the storage may be not the fastest, stat()'ing these > files was fine, but getfattr/setfattr took very long. > > I got curious and while it turned out that the slowness was related to the > wrapper script I used to read/set those values, I created a little test > suite to 1) create a few thousand files and 2) do xattr operations on > them and see if xattr performance was filesystem specific: > > http://nerdbynature.de/bits/xattr/ > > Not very sophisticated, true. But it was interesting to see that > ext3/ext4/xfs behaved kinda well for all these tests; btrfs/jfs/reiserfs > sometimes took way longer than the others.
Very interesting results! One wrinkle that you might want to consider with XFS is the overall size of the attributes versus the size of the inode. You can choose inode sizes between 256 bytes and 2k in powers of two, and we always allocate them in chunks of 64. The 'literal' area is the space after the inode core and before the next one... it's best described here: http://xfs.org/docs/xfsdocs-xml-dev/XFS_Filesystem_Structure//tmp/en-US/html/On-disk_Inode.html The short version: inode core (96 bytes) + literal area == inode size The data and attribute forks share the literal area. If the attributes get too big to fit inside the literal area with the data fork they will go out of line and be stored elsewhere in the filesystem. The performance characteristics of inline vs out-of-line attributes are significantly different. That might be what you experienced when you felt that setting/reading xattrs was taking a long time. Anyway... If you're a heavy user of EAs you might benefit from using larger inodes. Just something to consider. Cool tests! ;) Regards, Ben ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Jfs-discussion mailing list Jfs-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jfs-discussion