Re: [PATCH v2 6/7] p5326: generate pack bitmaps before writing the MIDX bitmap

From: Taylor Blau <me@ttaylorr.com>
Date: Sep 17, 2021, 04:20 UTC
Message-ID: <YUQXhsJYhxGdjSfL@nand.local>
In-Reply-To: <YUPJDf7u8Nn5als3@coredump.intra.peff.net>

On Thu, Sep 16, 2021 at 06:45:33PM -0400, Jeff King wrote:

Show 8 quoted lines

> It might be interesting to also do:
>
>   rm -f .git/objects/pack/pack-*.bitmap
>
> after generating the midx bitmap. That would confirm the further timing
> tests are using the midx bitmap, and not ever "cheating" by looking at
> the pack one (having poked in this direction before, I know that this
> all works, so it would be a future-proofing thing).

This and the suggestion to avoid timing the single pack bitmap generation are both good ones.

I think to be totally accurate we would want to drop the pack bitmap before every MIDX bitmap generation, but I also think that in practice it does not matter much.

The reuse code currently does not try too hard to recognize the situation of "oh, I selected the same exact commits and don't have to do any work". It kind of does eventually, but only after doing a lot of preparation.

So I'm dubious as to whether we're really timing anything *that* useful, but it's probably worth keeping around anyway.

Thanks, Taylor