From: SZEDER Gábor <szeder@ira.uka.de>
Date: Tue, 07 Dec 2010 09:58:18 GMT
Subject: Re: [PATCH] describe: Don’t look up commits with --exact-match
Message-ID: <20101207095818.GB1867@neumann>
In-Reply-To: <alpine.DEB.2.02.1012061159500.23348@dr-wily.mit.edu>

Hi,

On Mon, Dec 06, 2010 at 12:28:59PM -0500, Anders Kaseorg wrote:
> This makes ‘git describe --exact-match HEAD’ about 15 times faster on
> a cold cache (2.3s instead of 35s) in a linux-2.6 repository with many
> packed tags.  That’s a huge win for the interactivity of the __git_ps1
> shell prompt helper.

I wanted to give it a try to see the performance improvements in the
bash prompt for myself, but couldn't get to it so far.  However,
glancing through the logic finding out the current branch in
__git_ps1, it seems that git describe is only run when git
symbolic-ref HEAD failed, i.e. when on a detached head.  So the
performance improvement in the shell prompt is only there when on a
detached head (and with lots of tags), right?  If so, then I'd like to
have "when on a detached head" appended to the commit message.


Best,
Gábor