2690v2 disabling cpu affinity makes 5-10% imrovement

[mocksoul]

Hi!

I tried to disable cpu affinity completely and that makes up to 10% improvement (usually around 5-7%).
linux 5.10.27 custom built kernel

2x2690v2 3.3GHz OC, 512G RAM, numa memory interleaving enabled (saw speedups in 2 phase =)). 20 cores total (40 threads). ~25-50% cpu other processes usage.

Probably would be good idea to add --no-cpu-affinity switch at least? What do you think?

update: ctx switches dropped 50% by this & numa interleave change in this system

update: made quick test on 80 core system (cascade lake, cloud). Turning off cpu affinity leads to huge system kernel use in phase1 :)). It is 3-4 times slower with cpu affinity off. So, not all systems will benefit on turning off affinity..

[harold-b]

Agreed on the disabling cpu affinity switch, and I was going to add it to that commit but decided against it as it already had too many things.

I’ll see about doing another update tonight.

really appreciate these reports!

Unrelated: Were you able resolve the pool errors with the latest update?

[mocksoul]

Unrelated: Were you able resolve the pool errors with the latest update?

yes. Big thumbs up for that!

[koiesmith]

Mocksoul - by chance can you share your commands you used to turn settings on and off in Linux and run the benchmarks. I have lots of servers with v2,v3, and v4 procs and I'm trying to optimize them but learning Linux at the same time!!

[harold-b]

FYI the current develop has support for turning off cpu affinity via the --no-cpu-affinity switch. It also include a substantial optimization for sorting on Phase 1 (typically getting 20+ seconds saved, depending on the system) so you might want to test with that branch.