On Sat, 30 May 2020 08:42:59 -0600 (MDT) Solene Rapenne <sol...@openbsd.org>:
> CVSROOT: /cvs > Module name: src > Changes by: sol...@cvs.openbsd.org 2020/05/30 08:42:59 > > Modified files: > sys/kern : sched_bsd.c > > Log message: > In automatic performance mode on systems with offline CPUs because of > SMT mitigation the algorithm was still accounting the offline CPUs, > leading to a code path that would never be reached. > > This should allow better frequency scaling on systems with many CPUs. > The frequency should scale up if one of two condition is true. > - if at least one CPU has less than 25% of idle cpu time > - if the average of all idle time is under 33% > > The second condition was never met because offline CPU are always > accounted as 100% idle. > > A bit more explanations about the auto scaling in case someone want > to improve this later: When one condition is met, CPU frequency is > set to maximum and a counter set to 5, then the function will be run > again 100ms later and decrement the counter if both conditions are > not met anymore. Once the counter reach 0 the frequency is set to > minimum. This mean that it can take up to 100ms to scale up and up to > 500ms to scale down. > > ok brynet@ > looks good tedu@ > I forgot to credit claudio@ who shared the code to skip offline cpu
