Re: Rebase performance

> Hi Matthieu,
>
> On Thu, 25 Feb 2016, Matthieu Moy wrote:
>
>> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>>
>> > At the risk of derailing this thread, a thing that would make rebase
>> > even faster I think would be to change it so that instead of applying
>> > a patch at a time to the working tree the whole operation takes place
>> > on temporary trees & commits and then we'll eventually move the branch
>> > pointer to that once it's finished.
>> >
>> > I.e. there's no reason for why a sequence of 1000 patches where a
>> > FOO.txt is changed from "hi1", "hi2", "hi3", ... would be noticeably
>> > slower than applying the same changes with git-fast-import.
>>
>> Also, not touching the worktree during rebase would have the advantage
>> that if the final result doesn't change a file, we wouldn't need to
>> touch this file at all, hence the next "make" (or whatever
>> timestamp-using build system the user runs) would consider this file
>> unchanged.
>
> We still have to write all blobs. So I would still expect this to be I/O
> bound.