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@

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/kern/sched_bsd.c b/sys/kern/sched_bsd.c
index 7806cc42c6b..888197d5fc1 100644
--- a/sys/kern/sched_bsd.c
+++ b/sys/kern/sched_bsd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sched_bsd.c,v 1.62 2020/01/30 08:51:27 mpi Exp $	*/
+/*	$OpenBSD: sched_bsd.c,v 1.63 2020/05/30 14:42:59 solene Exp $	*/
 /*	$NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $	*/
 
 /*-
@@ -576,6 +576,8 @@ setperf_auto(void *v)
 	j = 0;
 	speedup = 0;
 	CPU_INFO_FOREACH(cii, ci) {
+		if (!cpu_is_online(ci))
+			continue;
 		total = 0;
 		for (i = 0; i < CPUSTATES; i++) {
 			total += ci->ci_schedstate.spc_cp_time[i];