Re: [PATCH 0/1] commit-graph: avoid unnecessary tag deference when merging

> On Fri, Mar 20, 2020 at 09:56:16PM -0700, Junio C Hamano wrote:
>
> > Taylor Blau <me@ttaylorr.com> writes:
> >
> > > This patch avoids an unnecessary tag dereference in
> > > 'merge_commit_graph()', which can improve the running time of a
> > > commit-graph write by around ~7.4% on average.
> >
> > That I suspect depends heavily on what portion of your total
> > committishes consist of tags, no (in an absurdly extreme case, if
> > there is no tag in the repository, there won't be any improvement)?
> >
> > What tag-vs-commit ratio is the above "average" number based on?
>
> I think the point is that in this code path we've already identified the
> candidates as commits (because they were in an existing commit-graph
> file), so treating the items as a committishes in the first place is
> unnecessary. If an object isn't itself a commit, we should be dropping
> it from the proposed output (possibly we ought to give a warning in such
> a case, too, as it indicates the previous writer did something wrong).