Hi Ted: On Mon, Apr 27, 2009 at 3:40 PM, Theodore Tso <tytso@xxxxxxx> wrote: > On Sun, Apr 26, 2009 at 11:29:39PM -0600, Curt Wohlgemuth wrote: >> The random read throughput on the 10GB file went from ~16 MB/s to ~22 >> MB/s after Andreas' patch; the total fragmentation of the file was >> much lower than before his patch. >> >> However, the number of extents went up by quite a bit (I don't have >> the debugfs output in front of me at the moment, sorry). > > I'm curious what you meant by the combination of these two statements, > "the total fragmentation of the file was much lower than before his > patch", and "the number of extents went up by quite a bit". Can you > send me the debugfs output when you have a chance? Sorry it's been so long for me to reply. Okay, my phrasing was not as precise as it could have been. What I meant by "total fragmentation" was simply that the range of physical blocks for the 10GB file was much lower with Andreas' patch: Before patch: 8282112 - 103266303 After patch: 271360 - 5074943 The number of extents is much larger. See the attached debugfs output. Here's the output of "e2fsck -E fragcheck" on the block devices; remember, though, that each one has only 3 files: -rw-rw-r-- 1 root root 10737418240 Apr 23 15:33 10g -rw-rw-r-- 1 root root 4294967296 Apr 23 15:30 4g -rw-rw-r-- 1 root root 4294967296 Apr 23 15:30 4g-2 drwx------ 2 root root 16384 Apr 23 15:27 lost+found/ Before patch: e2fsck 1.41.3 (12-Oct-2008) /dev/hdm3: clean, 14/45760512 files, 7608255/183010471 blocks After patch: e2fsck 1.41.3 (12-Oct-2008) /dev/hdo3: clean, 14/45760512 files, 7608258/183010471 blocks Thanks, Curt
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debugfs.before-patch
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debugfs.after-patch
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