On Fri, Jul 30, 2010 at 11:01:36PM +0200, Kay Diederichs wrote: > whereas for 2.6.32.16 the result is typically > Filesystem type is: ef53 > File size of > /mnt/md5/scratch/nfs-test/tmp/xds/frames/h2g28_1_00000.cbf is > 6229688 (1521 blocks, blocksize 4096) > ext logical physical expected length flags > 0 0 826376200 1521 eof > /mnt/md5/scratch/nfs-test/tmp/xds/frames/h2g28_1_00000.cbf: 1 extent found OK, so 2.6.32 is actually doing a better job laying out the files.... The blktrace will be interesting, but at this point I'm wondering if this is a generic kernel-wide writeback regression. At $WORK we've noticed some performance regressions between 2.6.26-based kernels and 2.6.33- and 2.6.34-based kernels with both ext2 and ext4 (in no journal mode) that we've been trying to track down. We have a pretty large number of patches applied to both 2.6.26 and 2.6.33/34 which is why I haven't mentioned it up until now, but at this point it seems pretty clear there are some writeback issues in the mainline kernel. There are half a dozen or so patch series on LKML that are addressing writeback in one way or another, and writeback is a major topic at the upcoming Linux Storage and Filesystem workshop. So if this is the cause, hopefully there will be some improvements in this area in the near future. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
