2011-09-6, 11:21(-05), Andrew Carlson: > I was doing some testing with writing out data to a BTFS filesystem > with the compress-force option. With 1 program running, I saw > btfs-delalloc taking about 1 CPU worth of time, much as could be > expected. I then started up 2 programs at the same time, writing data > to the BTRFS volume. btrfs-delalloc still only used 1 CPU worth of > time. Is btrfs-delalloc threaded, to where it can use more than 1 CPU > worth of time? Is there a threshold where it would start using more > CPU? [...]
Hiya, I observe the same here. The bottleneck when writing data sequencially seems to be that btrfs-delalloc using 100% of the time of one CPU. If I do several writes in parallel, a few more btrfs-delalloc's appear (3 when filling up 5 files concurrently), but btrfs-delalloc is still the bottleneck. Interestingly, if I write to 10 files simultanously, I see only two btrfs-delalloc and the throughput is lower. That's on ubuntu 11.10 3.0.0-13 amd64, 12 core, 16GB DDR3 1333MHz RAM. raid10 on 6 drives. Note that zfsonlinux does perform a lot better in that regard (on a raidz (ZFS raid5) on those same 6 drives): 50% CPU utilisation and max out the disk bandwidth. -- Stephane -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
