phoronix benchmarks ext4 vs. btrfs

[Chris Murphy]

I'm not sure how useful 'time' is as a benchmark for file copies. But that's what I used getting copy time for a folder containing 325 ~7.2MB files (DNGs) totaling 2.3G. First I copied the files to tmpfs, and made all copies from that to the destination. Destination device and partition is always the same, only file system differs. I used default mkfs and mount options. 1st copy is the first copy after mounting the newly created file system. Delay between copies varied somewhat, between 15-30 seconds.

The one anomaly is the 3rd ext4 copy. Maybe it wasn't quite done writing out the 2nd copy? Compared to btrfs and XFS, there was a lot of intermittent disk activity well after the copy had finished - over 1 minute. I'm not sure what it was doing, but was consistent for all of its copies. Copies were not overwrites, but into a separate directory.

btrfs average real    21.45s
xfs average real      22.81s
ext4 average real   29.31

Anyway, I only did this because having used btrfs moderately for a while now, it doesn't seem as slow as the various benchmarks keep making it out to be. This test may be meaningless as I'm not sure if the termination of the cp command is an appropriate metric at all. And the actual time between copies being variable might also pollute the result. However, except for the 3rd ext4 copy, there's pretty reasonable consistency.




detail:

1st copy to btrfs
real	0m22.881s
user	0m0.028s
sys	0m3.993s

---------
2nd copy to btrfs

real	0m20.793s
user	0m0.024s
sys	0m3.899s

------------
3rd copy to btrfs

real	0m21.641s
user	0m0.024s
sys	0m3.882s

----------
4th copy to btfs

real	0m20.502s
user	0m0.030s
sys	0m5.068s

=================

1st copy to xfs

real	0m23.969s
user	0m0.022s
sys	0m6.877s

-----------------------

2nd copy to xfs

real	0m23.452s
user	0m0.027s
sys	0m6.989s

-----------------------

3rd copy to xfs

real	0m21.243s
user	0m0.031s
sys	0m6.838s

-----------------------

4th copy to xfs

real	0m22.589s
user	0m0.030s
sys	0m6.617s

==========

1st copy to ext4

real	0m28.181s
user	0m0.026s
sys	0m11.510s

-----------------

2nd copy to ext4

real	0m27.321s
user	0m0.021s
sys	0m12.208s

---------------

3rd copy to ext4

real	0m35.036s
user	0m0.026s
sys	0m12.441s

------------------

4th copy to ext4

real	0m26.719s
user	0m0.035s
sys	0m11.511s
====================