Re: Why is --graph --max-count=n so much slower than --graph HEAD~n..?

From: Junio C Hamano <gitster@pobox.com>
Date: May 21, 2014, 00:24 UTC
Message-ID: <CAPc5daWBKa2kTe6jEcNk2=Xqh+R-mMFqL2tTpHERtPjPkAAvGg@mail.gmail.com>
In-Reply-To: <vnkw4n0kat01.fsf@mitchelh-linux.qualcomm.com>

Surely. I am on a bus with terrible WiFi that does not let me use the usual terminal, but you would find a code in revision.c that sets revs->topo_order = 1 when it parses "--graph" option. If you disable it, that would stop "--graph" from wanting to compute the whole history before starting to emit stuff (and then stop at nth one with --max-count).

I do not know what other side effects such a change would have, though.

On Tue, May 20, 2014 at 5:13 PM, Mitchel Humpherys <mitch.special@gmail.com> wrote:

Show 20 quoted lines

> On Tue, May 20 2014 at 03:50:43 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Mitchel Humpherys <mitch.special@gmail.com> writes:
>>
>>> I've noticed that --max-count doesn't seem to speed up `git log --graph'
>>> computation time.
>>
>> AFAIK, --graph wants to compute the whole history and the max-count
>> only affects the output phase after --graph does its computation.
>>
>> Besides, "log --max-count=n" and "log HEAD~n.." compute completely
>> different things, so the comparison is apples and oranges.
>
> Yes, apples and oranges in a black box :). I provided the
> HEAD~n.. measurements just to show that we can get (almost) the exact
> same output another way and it's much faster. It just "seems like"
> --max-count=n should speed things up as n decreases...
>
>
> --
> Mitch