Re: Perf bug: rev-list w/ 2+ paths relatively slow with commit-graph

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 23, 2025, 21:00 UTC
Message-ID: <xmqq34bq5g29.fsf@gitster.g>
In-Reply-To: <CADYQcGrR0mKLEWSYZCrL6b7NYLGfdsZsuKCCFQ_ptpMJ8mofmQ@mail.gmail.com>

Kai Koponen <kaikoponen@google.com> writes:

Show 5 quoted lines

> I see, more of a perf FR than a bug then.
> I don't have much expertise here, but on the surface of it, it doesn't
> seem to me like there would be any reason the algorithm couldn't check
> each path's bloom filter in turn while searching, other than that this
> would be a large and annoying change.

It looks like that the necessary changes are probably fairly well isolated to two functions, i.e., prepare_to_use_bloom_filter() and forbid_bloom_filters(). Right now, for a pathspec that has one element "dir/file", the code uses two bloom keys for "dir" and "dir/file", but if we have "dir1/file1" as well, then it does look like a matter of using two more (and the bloom_keys[] array is designed to be variable length).

But those who have more intimate knowledge in the area than I do may point out what is missing in my "it looks like" gut feeling.