Re: [PATCH v3] xdiff: disable cleanup_records heuristic with --minimal

[Junio C Hamano <gitster@pobox.com>]

Phillip Wood <phillip.wood123@gmail.com> writes:

> Hi Niels
>
> On 29/04/2025 15:09, Niels Glodny wrote:
>> The cleanup_records function marks some lines as changed before running
>> the actual diff algorithm. For most lines, this is a good performance
>> optimization, but it also marks lines that are surrounded by many
>> changed lines as changed as well. This can cause redundant changes and
>> longer-than-necessary diffs.
>> Whether this results in better-looking diffs is subjective. However,
>> the
>> --minimal flag explicitly requests the shortest possible diff.
>> The change results in shorter diffs in about 1.3% of all diffs in
>> Git's
>> history. Performance wise, I have measured the impact on
>> "git log -p -3000 --minimal > /dev/null". With this change, I get
>>    Time (mean ± σ): 2.363 s ±  0.023 s (25 runs)
>> and without this patch I measured
>>    Time (mean ± σ): 2.362 s ±  0.035 s (25 runs).
>> As the difference is well within the margin of error, this does not seem
>> to have an impact on performance.
>
> Thanks for adding the performance information, this version looks good
> to me.
>
> Best Wishes
>
> Phillip

Yup, thanks, both of you.