Re: Git performance on OS X

On Sat, 19 Apr 2008, Roman Shaposhnik wrote:

quoted

Is there any system-level profiler for OS X to get a clue where that cost
is, in case it's not the lstat() at all?

If it happens on Leopard, DTrace would be a perfect way to query the system:

Well, I'd really like to see a traditional _time_ profile, not system 
call counts.

The system call profile is trivial - it's generally going to be pretty 
similar under OS X and Linux (modulo library differences, but git doesn't 
really use any really complex libraries that would do system calls).

The problem we've had in the past is that Linux is simply an order of 
magnitude faster (sometimes more) at some operations than OS X is, so 
issues that show up on OS X don't even show up on Linux.

This was the case for doing lots of small "mmap()/munmap()" calls, for 
example, where we literally had a load where OS X was two orders of 
magnitude slower. We switched over to reading the files with "pread()" 
instead of mmap(), and that fixed that particular issue.

So a real system profile would be nice.

			Linus