Re: [PATCH 4/4] t5326: test propagating hashcache values

On Sun, Sep 12, 2021 at 05:46:18PM -0700, Junio C Hamano wrote:

What I am wondering is if we can come up with a "now, because we no
longer lose hashcache, we can do X so much better, here are the
numbers".

Sure, here they are. Bear in mind that these numbers are (a) on git.git
and (b) with `pack.threads` set to 1 so the overall runtime looks more
like CPU time.

  Test                            origin/tb/multi-pack-bitmaps   HEAD
  -------------------------------------------------------------------------------------
  5326.4: simulated clone         1.87(1.80+0.07)                1.46(1.42+0.03) -21.9%
  5326.5: simulated fetch         2.66(2.61+0.04)                1.47(1.43+0.04) -44.7%
  5326.6: pack to file (bitmap)   2.74(2.62+0.12)                1.89(1.82+0.07) -31.0%

Apologies for taking a little while to respond, I spent longer than I'm
willing to admit double checking these numbers with Peff because of
inconsistencies in my testing setup.

Alas, there they are. They are basically no different than having the
name-hash for single pack bitmaps, it's just now we don't throw them
away when generating a MIDX bitmap from a state where the repository
already has a single-pack bitmap.

Thanks,
Taylor