Re: Performance (self-compiled vs. distributed)

From: D. Ben Knoble <ben.knoble@gmail.com>
Date: Sep 4, 2025, 14:05 UTC
Message-ID: <CALnO6CCEF75uriogAEd5LfORJ-m9OmDcF7ubu-U_xLWwxfZWTQ@mail.gmail.com>
In-Reply-To: <CALnO6CA3FkiOeF4w1TUf9S_UDTG_1iRxjEZcAkfrL_eqY+P26w@mail.gmail.com>

On Wed, Sep 3, 2025 at 4:31 PM D. Ben Knoble <ben.knoble@gmail.com> wrote:

Show 24 quoted lines

>
> I have an installation of Git at /usr/local/bin/git managed by
> Homebrew. I'm also tinkering with building my own Git (+ patches) to
> experiment with new features. Today I used "make install …" to get
> that in ~/bin/git, but I'm noticing some performance problems. My
> shell prompt started coming back slower, especially in a large
> monorepo.
>
> For example, inside said monorepo (apologies in advance; output is on
> a computer I can't easily copy from):
>
>     hyperfine -Ni -w10 {/usr/local,$HOME}/bin/git
>     …
>     /usr/local/bin/git ran 4.99 +/- 1.69 times faster than ~/bin/git
>
> The difference is 22ms +/- 6.5ms (15.3ms–56.3ms) compared to 109.7ms
> +/- 17.8ms (91.1ms–159.9ms).
>
> My build recipe was
>
>     export DEVELOPER=1
>     export XML_CATALOG_FILES=/usr/local/etc/xml/catalog
>     make -j "$(nproc)" all doc
>     make install install-doc install-html

Interesting. It was suggested off-list that I should try building with CFLAGS=-Oz, which I'm having some trouble propagating (with V=1, I see some initial files built with -Oz and then later some with -O2??).

But on my other (non-corporate-managed) machine, I see almost no timing difference between a built Git and a Homebrew-installed Git. So I wonder if the corporate binary sniffer is causing problems…

-- 
D. Ben Knoble