Re: git-bisect problem

[Junio C Hamano <junkio@cox.net>]

Andrew Morton <akpm@osdl.org> writes:

> git-format-patch -o ~/a 386093ef9a6c88576d8b418bf1c8616d5e410a20 git-netdev-all
>
> and that chewed 10 minutes CPU time and produced no output, so I killed it.

A single commit is either:

	git format-patch -o ~/a 386093^ 386093
	git show 386093

But if you _did_ want to get everything that builds on top of
386093 (and Linus counted 1000+ commits if I recall),
format-patch could be optimized.  It currently does a lot more
than just format 1000+ commits, to handle case where "his" and
"mine" are not linear history and may have the same change
acquired by applying the same patch:

          1---2---3 mine
         /
     ---4---5---6 his

In this picture, it does not just format 1 2 3.  It first checks
1 2 3 5 6, and if each of 1 2 3 introduces the same change as
either 5 or 6 introduces to omit it from the output.  If 2 and 5
are the same change from 1 and 4 respectively, the final result
has 1 and 3.  This is OK and useful for smaller branch, but
clearly expensive for long branches.

This is omitted when the ancestry graph would look like this:
	
          1---2---3 mine
         /
     ---4 his

but that would not have helped in this case anyway.

Maybe we could have --no-omit-common flag or something to
disable this check.