Hi,
I see that btrfs is using kernel workqueues since linux 3.15. After
some tests I noticed performance regressions with fs_mark.
mount options: rw,relatime,compress=lzo,space_cache
fs_mark on Kernel 3.14.9:
# fs_mark -d /mnt/btrfs/fsmark -D 512 -t 16 -n 4096 -s 51200 -L5 -S0
FSUse% Count Size Files/sec App Overhead
1 65536 51200 17731.4 723894
1 131072 51200 16832.6 685444
1 196608 51200 19604.5 652294
1 262144 51200 18663.6 630067
1 327680 51200 20112.2 692769
The results are really nice! compress=lzo performs very good.
fs_mark after upgrading to Kernel 3.15.4:
# fs_mark -d /mnt/btrfs/fsmark -D 512 -t 16 -n 4096 -s 51200 -L5 -S0
FSUse% Count Size Files/sec App Overhead
0 65536 51200 10718.1 749540
0 131072 51200 8601.2 853050
0 196608 51200 11623.2 558546
0 262144 51200 11534.2 536342
0 327680 51200 11167.4 578562
That's really a big performance regression :(
What do you think? It's easy to reproduce with fs_mark.
Thank you.
Best regards,
Morten
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