bzr, git, and hg performance on the Linux tree

OK, so I just did a historical comparison of git and bzr performance using the Linux source tree. One of the comments I got was “what about Mercurial?” Fair enough. I’ve really never done much with Mercurial because Ubuntu primarily uses bzr and git is what most of the other people I know using a DVCS use. However, there are a lot of projects using Mercurial, Mozilla being probably the most notable one. So, here’s a comparison of bzr and hg. You may want to read my previous post for details on the steps I’m doing.

Repo Initialization:
git                bzr                hg
0m0.086s     0m0.334s     0m0.137s
1        :         3.88      :      1.59

Add 2.6.0 Linux tree:
git                bzr                hg
0m14.269s   0m4.852s      0m2.526s
5.65      :      1.92      :       1

Commit 2.6.0 Linux tree:
git                bzr                 hg
0m10.263s   0m43.968s    0m30.890s
1         :        4.28       :       3.01

Diff after copying in 2.6.25.2 Linux tree:
git                bzr                hg
0m24.425s   0m51.158s    0m37.846s
1        :         2.09      :      1.55

Committing large changes:
git                bzr                hg
0m28.468s   1m8.627s     0m47.948s
1        :         2.41      :        1.68

Diff after no changes:
git                bzr                hg
0m0.343s     0m47.448s    0m1.340s
1         :        138       :       3.91

Getting repo status after no changes:
git                bzr                hg
0m1.230s     0m4.027s     0m1.077s
1.14       :      3.74      :     1

Committing a trivial change:
git                bzr                hg
0m0.397s    0m9.010s      0m1.913s
1        :        22.7       :       4.82

Repository size (just VCS control directory):
git (gc)        bzr (pack)      hg
92 MB         112 MB          179 MB

So, Mercurial performs quite well. It generally sits somewhere between git and bzr. Hg runs somewhere around 2.75 times slower than git in the tested operations. Bzr runs around 5 times slower with the notable exception that bzr diff when there are no changes is 138 times slower than git and 35 times slower than Hg.