On Thu, Sep 02, 2021 at 07:16:43PM +0200, Christian Weisgerber wrote:
> Stefan Sperling:
> 
> > > I'd be fine with this if people prefer performance over sanity checks.
> > 
> > Update: We should then also drop the head_ref variable.
> 
> My test case is the Git conversion of OpenBSD src,
> got branch -c cb8c029a90 local, and cherrypicking the commits in
> usr.bin/rsync:
> got cy 57987d16c1
> got cy 722539fd92
> got cy fecc32f18d
> got cy ede24f484b,
> got cy 0345af144f
> 
> And I ran that on an APU2.  Slow by x86 standards, pretty fast by
> non-x86 standards.
> 
> With HEAD:
>     5m50.33s real     4m02.36s user     2m04.41s system
> 
> With your patch:
>     1m04.92s real     0m28.24s user     0m36.54s system
> 
> That's a lot faster.

Yes. This shows that skipping the ancestry check is worth it.

> It's still fairly slow, though.

Needs profiling to dig deeper.

Can you time 'got tree -R'? In the general case we won't be able
to make cherrypick/backout any faster than that.

> Backout of the same commits from the tip of master:
>     1m07.46s real     0m29.40s user     0m38.02s system