Re: [PATCH v2] send-pack.c: add config push.useBitmaps

From: Derrick Stolee <derrickstolee@github.com>
Date: Jun 16, 2022, 13:02 UTC
Message-ID: <e2ea1475-ce21-ef52-7301-3ed074c40f9b@github.com>
In-Reply-To: <pull.1263.v2.git.1655350617442.gitgitgadget@gmail.com>

On 6/15/2022 11:36 PM, Kyle Zhao via GitGitGadget wrote:

Show 33 quoted lines

> From: Kyle Zhao <kylezhao@tencent.com>
> 
> This allows you to disable bitmaps for "git push". Default is false.
> 
> Reachability bitmaps are designed to speed up the "counting objects"
> phase of generating a pack during a clone or fetch. They are not
> optimized for Git clients sending a small topic branch via "git push".
> In some cases (see [1]), using reachability bitmaps during "git push"
> can cause significant performance regressions.
> 
> Add a new "push.useBitmaps" config option to disable reachability
> bitmaps during "git push". This allows reachability bitmaps to still
> be used in other areas, such as "git rev-list --use-bitmap-index".
> 
> [1]: https://lore.kernel.org/git/87zhoz8b9o.fsf@evledraar.gmail.com/
> 
> Signed-off-by: Kyle Zhao <kylezhao@tencent.com>
> ---
>     send-pack.c: add config push.useBitmaps
>     
>     This patch add config push.useBitmaps to prevent git push using bitmap.
>     
>     The origin discussion is here:
>     https://lore.kernel.org/git/b940e705fbe9454685757f2e3055e2ce@tencent.com/
>     
>     Thanks, -Kyle
>     
>     Changes since v1:
>     
>      * changed the commit message
>      * modified and added missing \n to push.txt
>      * used test_subcommand for test
>      * modified "if" statement for "git_config_get_bool()" in send-pack.c

This version satisfies the recommended changes I had from the last version. As long as we think there is a benefit to having this additional knob over just pack.useBitmaps, then this is good to go.

For my part, I think having the additional knob is less complicated than requiring all users in this situation to shift from "push" to a "fetch" (from the other side of the connection).

Thanks, -Stolee