From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH] rev-list: estimate number of bisection step left
Date: Mon, 16 Feb 2009 23:28:18 -0800
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References: <20090217060944.488184b0.chriscool@tuxfamily.org>
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Cc: git@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
To: Christian Couder <chriscool@tuxfamily.org>
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In-Reply-To: <20090217060944.488184b0.chriscool@tuxfamily.org> (Christian
 Couder's message of "Tue, 17 Feb 2009 06:09:44 +0100")
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Christian Couder <chriscool@tuxfamily.org> writes:

> +static int estimate_bisect_steps(int all)
> +{
> +	int log2 = 0;
> +	int left = (all >> 1) - 1;
> +
> +	if (left <= 0)
> +		return 0;
> +
> +	do {
> +		left = left >> 1;
> +		log2++;
> +	} while (left);
> +
> +	return log2;
> +}
> ...
> diff --git a/git-bisect.sh b/git-bisect.sh
> index 85db4ba..6b23439 100755
> --- a/git-bisect.sh
> +++ b/git-bisect.sh
> @@ -500,7 +500,7 @@ bisect_next() {
>  	# commit is also a "skip" commit (see above).
>  	exit_if_skipped_commits "$bisect_rev"
>  
> -	bisect_checkout "$bisect_rev" "$bisect_nr revisions left to test after this"
> +	bisect_checkout "$bisect_rev" "$bisect_nr revisions left to test after this (roughtly $bisect_steps steps)"

"roughly".

all	left
0	0
1	0
2	0
3	0
4	1
5	1
6	2
7	2
8	2
9	2

It seems that at the very low end the estimate is a bit too optimistic.
How about showing this number from the Porcelain only when $bisect_steps
is more than 2 (or all is more than 9)?