Re: [PATCH v3 0/3] automatically skip away from broken commits

From: Christian Couder <christian.couder@gmail.com>
Date: Jun 9, 2009, 04:24 UTC
Message-ID: <c07716ae0906082124n4a5bfe88md80ba8076c928b76@mail.gmail.com>
In-Reply-To: <7vzlcixwue.fsf@alter.siamese.dyndns.org>

On Mon, Jun 8, 2009 at 11:02 PM, Junio C Hamano<gitster@pobox.com> wrote:

Show 13 quoted lines

> "H. Peter Anvin" <hpa@zytor.com> writes:
>
>> The advantage of that -- and I have to admit I don't know if it will
>> ever matter in practice -- is that using an actual PRNG:
>>
>> a) is less likely to get into pathological capture behaviors.
>> b) doesn't make people think later that there is something magic to the
>>    arbitrary chosen numbers.
>
> My gut feeling agrees with you that both are likely to be true; these are
> good points.
>
> Christian, what do you think?

Here are some reasons why I think my algorithm might be better:

- using HPA's formula I get on average 0.86 bits of information at
each step when alternating (against 0.72 when using a PRNG)
- I think that if the branches in the graph merge often between each
other, then on a big scale it's like when you are on the linear case
- I don't think we should try too hard to avoid pathological capture
behaviors, because I think we can't avoid them anyway in some cases,
like if the first bad commit is near many untestable commits

In the end I think that when you have too many long and completely untestable branches for example, the right solution would be to have something that lets you cut them off your graph and bisect on a much cleaner graph, that's why I started working on "git replace" in the first place.

I think we should not penalize people who have a quite clean graph because some other people have a much dirtier one.

So I would be ok to implement a config option or a switch to "git bisect start" to let people use a PRNG instead of my algorithm but I think something like my algorithm should be the default.

Best regards, Christian.