Hi - I'm trying out btrfs again, and I see the same old bug in kernel 3.1.4 (Fedora 16, x86_64, dual-core), where after a few hours of writing, it switches from writing with several threads to writing with one: After: 21996 root 20 0 0 0 0 R 97.2 0.0 109:03.57 btrfs-delalloc- 23332 root 20 0 137m 14m 1000 S 3.3 1.0 5:40.32 tar 23333 root 20 0 125m 3620 960 D 2.7 0.2 4:33.04 tar 22026 root 20 0 0 0 0 S 2.0 0.0 3:14.73 btrfs-endio-wri 23626 root 20 0 0 0 0 S 2.0 0.0 0:17.64 kworker/0:0 55 root 20 0 0 0 0 S 1.3 0.0 6:46.35 kswapd0 22255 root 20 0 0 0 0 S 1.0 0.0 2:12.30 kworker/0:2 22025 root 20 0 0 0 0 S 0.3 0.0 3:16.34 btrfs-endio-wri Before: 23867 root 20 0 0 0 0 R 66.6 0.0 0:13.45 btrfs-delalloc- 24021 root 20 0 0 0 0 R 60.6 0.0 0:10.58 btrfs-delalloc- 24025 root 20 0 0 0 0 R 45.7 0.0 0:10.01 btrfs-delalloc- 24018 root 20 0 124m 2384 1116 R 8.6 0.2 0:03.31 tar 24019 root 20 0 124m 2276 1052 S 7.0 0.1 0:02.47 tar 55 root 20 0 0 0 0 S 2.6 0.0 6:47.92 kswapd0 24022 root 20 0 0 0 0 S 2.0 0.0 0:00.59 btrfs-endio-wri 22255 root 20 0 0 0 0 S 1.7 0.0 2:13.45 kworker/0:2 23626 root 20 0 0 0 0 S 1.7 0.0 0:18.84 kworker/0:0 24024 root 20 0 0 0 0 S 1.7 0.0 0:00.77 btrfs-endio-wri 23866 root 20 0 0 0 0 S 0.7 0.0 0:00.25 btrfs-submit-0 23912 root 20 0 0 0 0 D 0.3 0.0 0:00.26 flush-btrfs-4 It can be put back to its initial behaviour by unmounting and reloading the btrfs kernel module. I'm using compress-force=zlib for this, and it's writing with a tar-to-tar pipe (or rsync). I think switching to one thread it has a pretty negative impact on write speed (50%). I think the cause is writing lots of small files to the disk, but I can't be sure. Jeremy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
