* Instead of choosing the next thread if we skip one, we now choose the first thread

with a lower priority than the current one.
* Further reduced the probability to skip a thread to roughly 4%, that makes around
  13 skips per second, and about 40 msecs spend in lower priority threads per second
  (with a 3 msec quantum). Might still be too much, but we'll see.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19719 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/scheduler.cpp

@@ -197,12 +197,17 @@ scheduler_reschedule(void)
 			if (nextThread->queue_next && nextThread->queue_next->priority == B_IDLE_PRIORITY)
 				break;
 
-			// skip normal threads sometimes (roughly 12.5%)
-			if (_rand() > 0x1000)
+			// skip normal threads sometimes (roughly 4%)
+			if (_rand() > 0x500)
 				break;
 
-			prevThread = nextThread;
-			nextThread = nextThread->queue_next;
+			// skip until next lower priority
+			int32 priority = nextThread->priority;
+			while (nextThread->queue_next && priority == nextThread->queue_next->priority
+				&& nextThread->queue_next->priority > B_IDLE_PRIORITY) {
+				prevThread = nextThread;
+				nextThread = nextThread->queue_next;
+			}
 		}
 	}