Re: [PATCH 0/2] Make gc a builtin.

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mar 13, 2007, 01:20 UTC
Message-ID: <Pine.LNX.4.64.0703121815411.9690@woody.linux-foundation.org>
In-Reply-To: <et4s76$9u3$1@sea.gmane.org>

On Tue, 13 Mar 2007, Jakub Narebski wrote:

Show 7 quoted lines

> Linus Torvalds wrote:
> 
> > Another thing I find annoying (even as a UNIX user) is that whenever I do 
> > any tracing for performance data, shell is absolutely horrid. It's *so* 
> > much nicer to do 'strace' on built-in programs that it's not even funny.
> 
> Isn't that what GIT_TRACE was made for?

That just shows the high-level git commands.

If you look for performance issues or correctness issues (like when I tried to figure out if O_LARGEFILE was set for "git clone"), GIT_TRACE does nothing. You want to do "strace -f -o trace-file".

And shell scripts look horrible there, and make it much harder to follow things. In fact, it doesn't even need to be shell per se, but fork/exec already makes things harder to see, shell just tends to (a) make it even more so (try stracing though a shell startup, ugh) and (b) cause tons of fork/exec cases.

For example, when we made patch generation a built-in, it suddenly became *hugely* easier to follow what was going on in the traces, because it got much more streamlined. In general I find that "high performance" == "easy to trace".

		Linus