Re: blame now knows -S

From: Marco Costalba <mcostalba@gmail.com>
Date: Apr 8, 2006, 13:53 UTC
Message-ID: <e5bfff550604080653l2c73f844n8e03e55f9c467039@mail.gmail.com>
In-Reply-To: <20060408114240.GA10137@c165.ib.student.liu.se>

On 4/8/06, Fredrik Kuivinen <freku045@student.liu.se> wrote:

Show 20 quoted lines

> On Fri, Apr 07, 2006 at 02:28:40AM -0700, Junio C Hamano wrote:
> > I've made a few changes to "git blame" myself:
> >
> >  - fix breakage caused by recent revision walker reorganization;
> >  - use built-in xdiff instead of spawning GNU diff;
> >  - implement -S <ancestry-file> like annotate does.
> >
> > Depending on the density of changes, it now appears that blame
> > is 10%-30% faster than annotate.  I thought CVS emulator might
> > be interested to give it a whirl..
> >
>
> Nice work!
>
> There is another possible optimisation with respect to xdiff. Instead
> of producing the diff on the xdiff side and parsing the diff in
> blame.c, we could add another call back which just gets the relevant
> information from the hunk header. I don't know how much we would gain
> from this, but it might be worth a try.
>

If I can comment on this thread, I would like to note IMHO that given the differences in languages (C vs Perl) and the use of almost the same algorithm, just a 10%-30% in speed difference between blame and annotate it means that any further optimization can gain little because the bottleneck is elsewhere.

And I think is in getting the revision's history. Call it git-rev-list, although both blame and annotate use directly the library revision.h

After the new xdiff merge, git-rev-list accounts for almost whole the time. Normally more then 80% in qgit.

Although the qgit annotation algorithm is different from both blame and annotate I think that a faster git-rev-list <path> or revison history walker as you may want to call it it's a key in really speed-up annotation stuff.

    Marco