sched_steal_proc(): steal from highest loaded CPU

[Amit Kulkarni]

Hi,

When a cpu is idle, and wants to steal, it should steal from worst loaded cpu, 
i.e. with the highest cost, not the least cost.
Also, remove a dead store while here.

Thanks

Index: kern/kern_sched.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sched.c,v
retrieving revision 1.64
diff -u -p -u -p -r1.64 kern_sched.c
--- kern/kern_sched.c   30 Jan 2020 08:51:27 -0000      1.64
+++ kern/kern_sched.c   4 Feb 2020 14:25:59 -0000
@@ -487,7 +487,7 @@ sched_steal_proc(struct cpu_info *self)
        struct proc *best = NULL;
 #ifdef MULTIPROCESSOR
        struct schedstate_percpu *spc;
-       int bestcost = INT_MAX;
+       int bestcost = 0;
        struct cpu_info *ci;
        struct cpuset set;
 
@@ -515,7 +515,7 @@ sched_steal_proc(struct cpu_info *self)
 
                        cost = sched_proc_to_cpu_cost(self, p);
 
-                       if (best == NULL || cost < bestcost) {
+                       if (cost > bestcost) {
                                best = p;
                                bestcost = cost;
                        }
@@ -524,7 +524,6 @@ sched_steal_proc(struct cpu_info *self)
        if (best == NULL)
                return (NULL);
 
-       spc = &best->p_cpu->ci_schedstate;
        remrunqueue(best);
        best->p_cpu = self;