optinal load_avg to fix

kernel/proc.c

@@ -6,6 +6,8 @@
 #include "proc.h"
 #include "defs.h"
 
+uint64 load_avg = 0;
+
 struct cpu cpus[NCPU];
 
 struct proc proc[NPROC];
@@ -701,3 +703,23 @@ proc_size()
   }
   return n;
 }
+
+int
+get_current_load() {
+  struct proc *p;
+  int current_load = 0;
+
+  for (p = proc; p < &proc[NPROC]; p++) {
+    if (p->state == RUNNING || p->state == RUNNABLE) {
+      current_load++;
+    }
+  }
+
+  return current_load;
+}
+
+void
+update_load_avg() {
+  int current_load = get_current_load();
+  load_avg = (load_avg * ALPHA) + (current_load * (1 - ALPHA));
+}