[darcs-users] [issue1900] darcs seems particularly slow on MacOS X

[Florian Gilcher]

Okay, to stop guessing too much, I tried to come up with better numbers using OS X built-in dtrace-facility.

Syscall numbers:

http://hpaste.org/fastcgi/hpaste.fcgi/view?id=28351#a28351

Time spend in functions (in nanoseconds):

http://hpaste.org/fastcgi/hpaste.fcgi/view?id=28350#a28350

stat (and others) do not really seem to be the problem. Darcs spends the most time waiting, spending roughly
96% of the time in __semwait_signal, most probably because of read_nocancel and select. If you have a look 
at the call numbers, __semwait_signal is called very rarely, compared to the calls to read, mmap, etc.

Well, I have not investigated further and I do not have a lot of experience with both lower level darcs and
OS X internals, but this looks strange.

Darcs version was the recent beta release + mmap. The repository was the "optimized pristine" version of the 
GHC repos.

Regards,
Florian