Messages in this thread | | | Date | Sun, 31 Oct 2010 16:25:41 -0600 | Subject | Re: Horrible btrfs performance due to fragmentation | From | cwillu <> |
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On Sun, Oct 31, 2010 at 1:58 PM, Felipe Contreras <felipe.contreras@gmail.com> wrote: > On Mon, Oct 11, 2010 at 6:46 PM, Calvin Walton <calvin.walton@gmail.com> wrote: >> On Mon, 2010-10-11 at 03:30 +0300, Felipe Contreras wrote: >>> I use btrfs on most of my volumes on my laptop, and I've always felt >>> booting was very slow, but definitely sure is slow, is starting up >>> Google Chrome: >>> >>> encrypted ext4: ~20s >>> btrfs: ~2:11s >>> >>> I have tried different things to find out exactly what is the issue, >>> but haven't quite found it yet. >> >> If you've been using this volume for a while, it could just have become >> badly fragmented. You could try btrfs's fancy online defragmentation >> abilities to see if that'll give you an improvement: >> >> # btrfs filesystem defragment /mountpoint/of/volume >> >> Let us know if that helps, of course :) > > I finally managed to track down this issue. Indeed the fragmentation > is horrible, and 'btrfs filesystem defragment' doesn't help: > > % cat History-old > History > % btrfs filesystem defragment /home > % echo 3 > /proc/sys/vm/drop_caches > > % time dd if=History of=/dev/null && time dd if=History-old of=/dev/null > 109664+0 records in > 109664+0 records out > 56147968 bytes (56 MB) copied, 1.90015 s, 29.5 MB/s > dd if=History of=/dev/null 0.08s user 0.29s system 15% cpu 2.458 total > 109664+0 records in > 109664+0 records out > 56147968 bytes (56 MB) copied, 97.772 s, 574 kB/s > dd if=History-old of=/dev/null 0.07s user 0.80s system 0% cpu 1:37.79 total > > I think this is a serious issue that *must* be fixed for 1.0. I filed > a bug for this: > https://bugzilla.kernel.org/show_bug.cgi?id=21562
btrfs fi defrag isn't recursive. "btrfs filesystem defrag /home" will defragment the space used to store the folder, without touching the space used to store files in that folder. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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