[darcs-users] strace of darcs whatsnew on a biggish repo

[Alexander Staubo]

On Fri, Apr 25, 2008 at 12:35 AM, zooko <zooko at zooko.com> wrote:
>  A new user started to convert his company to darcs, but then had to
>  back out and go back to using SVN when it turned out that "darcs
>  whatsnew" took 17 seconds and his co-workers couldn't stand that.
>  (The equivalent call, "svn diff" takes around 1.7 seconds -- about
>  10x as fast.)

My experience is that Darcs performs rather poorly in the presence of
large, untracked files in the working directory. It probably reads
each file into memory, perhaps in order to determine whether it's
binary or not?

On OS X and probably other operating systems this forces the OS to
swap out pretty much everything to disk, which makes the system
virtually unusable while it's running and for a while afterwards, when
the OS needs to swap everything back in again.

I am intimately familiar with this issue because I tend to put 500MB
database dumps in my working directory before accidentally running
"darcs whatsnew".

> It looks like there is probably quite a bit of room for optimization
> in darcs-2's use of the filesystem.

Probably. Git and Mercurial do not suffer from this problem, either.

Alexander.