On Sat, 2020-06-27 at 17:00 +0300, Konstantin Kharlamov wrote:
Another reason worth mentioning: BTRFS per se is slow. If you look
on Phoronix comparing BTRFS with others, BTRFS is rarely even on par with
Btw, I should also add here: it may be clear that in ideal situtation BTRFS will
always be slower than non-COW file systems. The problem however, it is not even
on par with the other open-source COW file system, which is ZFS.
Some months ago at my dayjob I was performing benchmarks, and out of curiosity I
also compared latest released (as of then, it was 5.6 kernel) BTRFS with latest
master of ZFS (which was of a commit b29e31d80 and a kernel 5.4).
The setup was a RAID5 on 10 SSDs, and a benchmark was three 20-minutes long runs
of vdbench with random 70% reads and random 30% writes. For BTRFS I also used
`space_cache=v2` mount option. Results were:
FS | run 1, IOPS | run 2, IOPS | run 3, IOPS
BTRFS | 65723.9 | 56474.5 | 55090.2
ZFS | 96846.1 | 79797.9 | 76249.4
So, summing up this and my previous mail overall, I do not think that for
ordinary desktop BTRFS is currently any good, compared to EXT4 or XFS.