From: Christian Couder <christian.couder@gmail.com>
Date: Fri, 02 Jul 2021 13:45:13 GMT
Subject: Re: [PATCH 12/15] [GSOC] cat-file: reuse ref-filter logic
Message-ID: <CAP8UFD0P5eiwxKvot_5+izEjscyGw+F4QFN72BmgHNhi9V5S1w@mail.gmail.com>
In-Reply-To: <877di8al8n.fsf@evledraar.gmail.com>

On Fri, Jul 2, 2021 at 3:39 PM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>
> On Thu, Jul 01 2021, ZheNing Hu via GitGitGadget wrote:

> > The performance for `git cat-file --batch-all-objects
> > --batch-check` on the Git repository itself with performance
> > testing tool `hyperfine` changes from 669.4 ms ±  31.1 ms to
> > 1.134 s ±  0.063 s.
> >
> > The performance for `git cat-file --batch-all-objects --batch
> >>/dev/null` on the Git repository itself with performance testing
> > tool `time` change from "27.37s user 0.29s system 98% cpu 28.089
> > total" to "33.69s user 1.54s system 87% cpu 40.258 total".
>
> This new feature is really nice, but that's a really bad performance
> regression. A lot of software in the wild relies on "cat-file --batch"
> to be *the* performant interface to git for mass-extrction of object
> data.
>
> That's in increase of ~70% and ~20%, respectively. Have you dug into
> (e.g. with a profiler) where we're now spending all this time?

Yeah, I think it's better to discuss this performance issue as part of
the discussion of this series, instead of as part of the discussion of
the blog posts.