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Date: Fri, 27 Apr 2007 22:51:26 +0400 From: Alex Tomas <alex@...sterfs.com> To: Valerie Clement <valerie.clement@...l.net> CC: ext4 development <linux-ext4@...r.kernel.org> Subject: Re: Large File Deletion Comparison (ext3, ext4, XFS) Valerie Clement wrote: > As asked by Alex, I included in the test results the file fragmentation > level and the number of I/Os done during the file deletion. > > Here are the results obtained with a not very fragmented 100-GB file: > > | ext3 ext4 + extents xfs > ------------------------------------------------------------ > nb of fragments | 796 798 15 > elapsed time | 2m0.306s 0m11.127s 0m0.553s > | > blks read | 206600 6416 352 > blks written | 13592 13064 104 > ------------------------------------------------------------ hmm. if I did math right, then, in theory, 100GB file could be placed using ~850 extents: 100 * 1024 / 120, where 120 is amount of data one can allocate in regular group. 850 extents would require 3 leaf blocks (340 extents/block) + 1 index block. we'd need to read these 4 blocks + all 850 involved bitmaps + some blocks of group descriptors. so, probably we need to tune balloc. then we'd improve remove time by factor six (6400 blocks to read vs. ~900-1000 blocks to read) ? thanks, Alex - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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