Eric Sandeen wrote: > Eric Sandeen wrote: >> running fs_mark like this: >> >> fs_mark -d /mnt/test -D 256 -n 100000 -t 4 -s 20480 -F -S 0 >> >> (256 subdirs, 100000 files/iteration, 4 threads, 20k files, no sync) >> >> on a 1T fs, with and without delalloc (mount option), is pretty interesting: >> >> http://people.redhat.com/esandeen/ext4/fs_mark.png >> >> somehow delalloc is crushing performance here. I'm planning to wait >> 'til the fs is full and see what the effect is on fsck, and look at the >> directory layout for differences compared to w/o delalloc. >> >> But something seems to have gone awry here ... >> >> This is on 2.6.26 with the patch queue applied up to stable. >> >> -Eric > > I oprofiled both with and without delalloc for the first 15% of the fs fill: > > ==> delalloc.op <== > CPU: AMD64 processors, speed 2000 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a > unit mask of 0x00 (No unit mask) count 100000 > samples % image name app name > symbol name > 56094537 73.6320 ext4dev.ko ext4dev > ext4_mb_use_preallocated > 642479 0.8433 vmlinux vmlinux > __copy_user_nocache > 523803 0.6876 vmlinux vmlinux memcmp > 482874 0.6338 jbd2.ko jbd2 > do_get_write_access > 480687 0.6310 vmlinux vmlinux > kmem_cache_free > 403604 0.5298 ext4dev.ko ext4dev > str2hashbuf > 400471 0.5257 vmlinux vmlinux > __find_get_block > > ==> nodelalloc.op <== > CPU: AMD64 processors, speed 2000 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a > unit mask of 0x00 (No unit mask) count 100000 > samples % image name app name > symbol name > 56167198 56.8949 ext4dev.ko ext4dev > ext4_mb_use_preallocated This was wrong, I forgot to clear stats before re-running. With delalloc, the lg_prealloc list seems to just grow & grow in ext4_mb_use_preallocated, searching up to 90,000 entries before finding something, I think this is what's hurting - I need to look into how this should work. -Eric -- 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
