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. > This took some time be here it goes ... * B size files - total: 1064462 (53.81%) | Size range | File cnt | Fragmented | Fragmented % | | [0,100) | 288702 | 0 | 0 | | [100,200) | 165997 | 0 | 0 | | [200,300) | 45993 | 0 | 0 | | [300,400) | 64883 | 0 | 0 | | [400,500) | 39282 | 0 | 0 | | [500,600) | 61612 | 0 | 0 | | [600,700) | 208822 | 0 | 0 | | [700,800) | 64016 | 0 | 0 | | [800,900) | 58181 | 0 | 0 | | [900,1024) | 66974 | 0 | 0 | * K size files - total: 907375 (45.86%) | Size range | File cnt | Fragmented | Fragmented % | | [1,2) | 285481 | 0 | 0 | | [2,3) | 148461 | 0 | 0 | | [3,4) | 102569 | 0 | 0 | | [4,5) | 45089 | 0 | 0 | | [5,6) | 44223 | 0 | 0 | | [6,10) | 94202 | 0 | 0 | | [10,20) | 83760 | 0 | 0 | | [20,30) | 42548 | 0 | 0 | | [30,40) | 15274 | 0 | 0 | | [40,50) | 4060 | 0 | 0 | | [50,60) | 3517 | 0 | 0 | | [60,100) | 7834 | 0 | 0 | | [100,1024) | 30357 | 0 | 0 | *M size files - total: 6312 (0.33%) | Size range | File cnt | Fragmented | Fragmented % | | [1.10) | 5806 | 100 | 1.72 | | [10,100) | 482 | 200 | 41.49 | | [100,1024) | 24 | 13 | 54.16 | All files scanned: 1978149 Files fragmented: 313 (0.015%) where 11 have 3+ extents Total size of fragmented files: 7GB (~13% of dir size) 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 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 I will perform same tests on btrfs tomorrow. -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
