Re: [PATCH 0/7] Better threaded delta resolution in index-pack (another try)

[Jeff King <peff@peff.net>]

On Tue, Aug 25, 2020 at 05:18:36PM -0400, Jeff King wrote:

> Still maxes out at the number of physical cores (not unexpected, but
> that was the thing I was most curious about ;) ). I may run it on the
> 40-core machine, too. It's possible that with the new threading we're
> able to do better going past 20-threads. I doubt it, because I think
> it's mostly a function of Git's locking granularity, but worth checking.

For the curious (I know you were all on the edge of your seat):

  5302.3: index-pack 0 threads                    519.23(479.10+40.10) 
  5302.4: index-pack 1 threads                    525.94(476.27+49.64) 
  5302.5: index-pack 2 threads                    271.82(458.93+55.52) 
  5302.6: index-pack 5 threads                    115.88(463.84+50.69) 
  5302.7: index-pack 10 threads                   67.26(478.37+57.38)  
  5302.8: index-pack 20 threads                   43.02(524.01+77.33)  
  5302.9: index-pack 40 threads                   33.42(709.86+100.24) 
  5302.10: index-pack 80 threads                  32.02(1030.75+228.28)
  5302.11: index-pack default number of threads   43.58(551.13+68.92)  

So it actually does do a slight improvement to go from 20 to 40 threads
on this repository/machine combo. Not enough to make me revise the code
I sent the other day, though. And we still get nothing from going past
the number of physical cores.

-Peff