Benchmarks of COW directory copies and removal in [:cowbuilder: cowbuilder].

Details

The numbers in the copy column were generated using:

time sudo cp -al /var/cache/pbuilder/base.cow /tmp/new

and in the remove column:

time sudo rm -rf /tmp/new

Everything is in seconds. XFS filesystems:

computer

copy

remove

computer details

pc232

16.1

18.2

Intel Core 2 Duo, ST3250820AS /dev/sda1 (10GB, xfs, 80% full), sid, i386

pc232

9.0

10.0

Intel Core 2 Duo, ST3250820AS /dev/sda2 (10GB, xfs, 2.4% full), sid, i386

august

9.3

10.9

Intel Core 2 Quad, ST3320620AS /dev/sda1 (20GB, xfs, 20% full), sid, i386

august

5.8

9.5

Intel Core 2 Quad, ST3320620AS /dev/sda3 (233GB, xfs, 0.2% full), sid, i386

dakol

0.48

0.5

AMD Athlon 64 3800+, ST3160827AS /dev/sda7 (135GB, xfs, 32% full), sid, amd64

fuji

13.9

16.4

Intel Core Duo, WDC WD1600BEVS-2 /dev/sda1 (14GB, xfs, 33% full), sid, i386

Ext3 filesystems:

computer

copy

remove

computer details

pc232

0.2

0.14

Intel Core 2 Duo, ST3250820AS /dev/sda2 (10GB, ext3, 2.4% full), sid, i386

august

0.22

0.13

Intel Core 2 Quad, ST3320620AS /dev/sda5 (42GB, ext3, 0.9% full), sid, i386

dakol

0.22

0.15

AMD Athlon 64 3800+, ST3160827AS /dev/sda5 (2GB, ext3, 14.5% full), sid, amd64

Note 1: XFS filesystem was created using mkfs.xfs, ext3 filesystem was created with mkfs.ext3. No options added.

Note 2: On dakol with XFS filesystem, cp takes 0.5s, sudo sync takes 3s (!), rm takes 0.5s, and another sudo sync takes 2.8s. However, with ext3 filesystem, the sudo sync is negligible.

Conclusion

The ext3 filesystem is truly superior to XFS for the cowbuilder purpose. Just use it and you'll be fine.