Re: [PATCH v2 1/4] commit.c: add clear_commit_marks_many()

> On Tue, Mar 05, 2013 at 02:47:16PM -0800, Junio C Hamano wrote:
>
>> clear_commit_marks(struct commit *, unsigned) only can clear flag
>> bits starting from a single commit; introduce an API to allow
>> feeding an array of commits, so that flag bits can be cleared from
>> commits reachable from any of them with a single traversal.
>
> Out of curiosity, is that actually measurably more efficient?
>
> Since we stop traversing a commit's parents when we see it does not have
> any of the flags we are clearing, we should visit most commits once. The
> exception is ones that we hit by multiple paths. But that should
> be the same whether it is done as part of a single traversal or
> multiple; in each case, we hit the commit and say "Oh, already cleared;
> do not add it to the parents list".
>
> So I would expect it to have little to no impact on performance.  I
> still think it is a sane interface change; I was just curious from the
> commit message whether there could be a performance impact.