From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Mon, 02 Mar 2015 19:36:43 GMT
Subject: Re: Git Scaling: What factors most affect Git performance for a large repo?
Message-ID: <CACBZZX7O77zfn75vJXsSyR58UjC_bfTu-DWwJC8n2fhemVBn2w@mail.gmail.com>
In-Reply-To: <xmqqa908z44h.fsf@gitster.dls.corp.google.com>

On Fri, Feb 20, 2015 at 10:04 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>> I actually ran this a few times while testing it, so this is a before
>> and after on a hot cache of linux.git with 406 tags v.s. ~140k. I ran
>> the gc + repack + bitmaps for both repos noted in an earlier reply of
>> mine, and took the fastest run out of 3:
>>
>>     $ time (git log master -100 >/dev/null)
>>     Before: real    0m0.021s
>>     After: real    0m2.929s
>
> Do you force --decorate with some config?  Or do you see similar
> performance difference with "git rev-parse master", too?

Yes, I had log.decorate=short set in my config. With --no-decorate:

    $ time (git log --no-decorate -100 >/dev/null)
    # Before: real    0m0.010s
    # After: real    0m0.065s

>>     $ time (git status >/dev/null)
>>     # Around 150ms, no noticeable difference
>
> This is understandable, as it will not look at any ref other than
> HEAD.