2012/3/3 Jacek Luczak <difrost.kernel@xxxxxxxxx>: > 2012/3/2 Chris Mason <chris.mason@xxxxxxxxxx>: >> On Fri, Mar 02, 2012 at 03:16:12PM +0100, Jacek Luczak wrote: >>> 2012/3/2 Chris Mason <chris.mason@xxxxxxxxxx>: >>> > On Fri, Mar 02, 2012 at 11:05:56AM +0100, Jacek Luczak wrote: >>> >> >>> >> I've took both on tests. The subject is acp and spd_readdir used with >>> >> tar, all on ext4: >>> >> 1) acp: http://91.234.146.107/~difrost/seekwatcher/acp_ext4.png >>> >> 2) spd_readdir: http://91.234.146.107/~difrost/seekwatcher/tar_ext4_readir.png >>> >> 3) both: http://91.234.146.107/~difrost/seekwatcher/acp_vs_spd_ext4.png >>> >> >>> >> The acp looks much better than spd_readdir but directory copy with >>> >> spd_readdir decreased to 52m 39sec (30 min less). >>> > >>> > Do you have stats on how big these files are, and how fragmented they >>> > are? For acp and spd to give us this, I think something has gone wrong >>> > at writeback time (creating individual fragmented files). >>> >>> How big? Which files? >> >> All the files you're reading ;) >> >> filefrag will tell you how many extents each file has, any file with >> more than one extent is interesting. (The ext4 crowd may have better >> suggestions on measuring fragmentation). >> >> Since you mention this is a compile farm, I'm guessing there are a bunch >> of .o files created by parallel builds. There are a lot of chances for >> delalloc and the kernel writeback code to do the wrong thing here. >> > [Most of files are B and K size] > > All files scanned: 1978149 > Files fragmented: 313 (0.015%) where 11 have 3+ extents > Total size of fragmented files: 7GB (~13% of dir size) BTRFS: Non of files according to filefrag are fragmented - all fit into one extent. > tar cf on fragmented files: > 1) time: 7sec > 2) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_fragmented.png > 3) sw graph with spd_readdir: > http://91.234.146.107/~difrost/seekwatcher/tar_fragmented_spd.png > 4) both on one: > http://91.234.146.107/~difrost/seekwatcher/tar_fragmented_pure_spd.png BTRFS: tar on ext4 fragmented files 1) time: 6sec 2) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_fragmented_btrfs.png > tar cf of fragmented files disturbed with [40,50) K files (in total > 4373 files). K files before fragmented M files: > 1) size: 7.2GB > 2) time: 1m 14sec > 3) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_disturbed.png > 4) sw graph with spd_readdir: > http://91.234.146.107/~difrost/seekwatcher/tar_disturbed_spd.png > 5) both on one: > http://91.234.146.107/~difrost/seekwatcher/tar_disturbed_pure_spd.png BTRFS: tar on [40,50) K and ext4 fragmented 1) time: 56sec 2) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_disturbed_btrfs.png New test I've included - randomly selected files: - size 240MB 1) ext4 (time: 34sec) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_random_ext4.png 2) btrfs (time: 55sec) sw graph: http://91.234.146.107/~difrost/seekwatcher/tar_random_btrfs.png -Jacek -- 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
