Re: [PATCH v2 7/7] t5326: test propagating hashcache values
- From
Jeff King <peff@peff.net>
- Date
- Sep 16, 2021, 22:49 UTC
- Message-ID
- <YUPKDhi+rgwptZdY@coredump.intra.peff.net>
- In-Reply-To
- <fdf71432b32ef47b23b79ddfc3db8de8734ef7a5.1631657157.git.me@ttaylorr.com>
On Tue, Sep 14, 2021 at 06:06:16PM -0400, Taylor Blau wrote:
Show 19 quoted lines
> Now that we both can propagate values from the hashcache, and respect > the configuration to enable the hashcache at all, test that both of > these function correctly by hardening their behavior with a test. > > Like the hash-cache in classic single-pack bitmaps, this helps more > proportionally the more up-to-date your bitmap coverage is. When our > bitmap coverage is out-of-date with the ref tips, we spend more time > proportionally traversing, and all of that traversal gets the name-hash > filled in. > > But for the up-to-date bitmaps, this helps quite a bit. These numbers > are on git.git, with `pack.threads=1` to help see the difference > reflected in the overall runtime. > > 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%
The percentages here match timings I did. Doing it with linux.git gives bigger absolute numbers, but I think this is sufficient (and a lot less painful when people are trying to replicate).
Show 8 quoted lines
> +test_expect_success 'hash-cache values are propagated from pack bitmaps' ' > + rm -fr repo && > + git init repo && > + test_when_finished "rm -fr repo" && > + ( > + cd repo && > + > + git config pack.writeBitmapHashCache true &&
This is the default as of your earlier commits, so we could probably drop this. I don't mind keeping it as explicit documentation of what we expect, though.
-Peff