- Add an integer argument to idle to indicate how likely we are to wake

   from idle over the next tick.
 - Add a new MD routine, cpu_wake_idle() to wakeup idle threads who are
   suspended in cpu specific states.  This function can fail and cause the
   scheduler to fall back to another mechanism (ipi).
 - Implement support for mwait in cpu_idle() on i386/amd64 machines that
   support it.  mwait is a higher performance way to synchronize cpus
   as compared to hlt & ipis.
 - Allow selecting the idle routine by name via sysctl machdep.idle.  This
   replaces machdep.cpu_idle_hlt.  Only idle routines supported by the
   current machine are permitted.

Sponsored by:	Nokia

1 files changed, 9 insertions, 5 deletions

diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 7f5b597..7fe80af 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -954,6 +954,12 @@ tdq_notify(struct tdq *tdq, struct thread *td)
 		 */
 		if (tdq->tdq_idlestate == TDQ_RUNNING)
 			return;
+		/*
+		 * If the MD code has an idle wakeup routine try that before
+		 * falling back to IPI.
+		 */
+		if (cpu_idle_wakeup(cpu))
+			return;
 	}
 	tdq->tdq_ipipending = 1;
 	ipi_selected(1 << cpu, IPI_PREEMPT);
@@ -2095,10 +2101,7 @@ sched_clock(struct thread *td)
 	 * If there is some activity seed it to reflect that.
 	 */
 	tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
-	if (tdq->tdq_load)
-		tdq->tdq_switchcnt = 2;
-	else
-		tdq->tdq_switchcnt = 0;
+	tdq->tdq_switchcnt = tdq->tdq_load;
 	/*
 	 * Advance the insert index once for each tick to ensure that all
 	 * threads get a chance to run.
@@ -2507,9 +2510,10 @@ sched_idletd(void *dummy)
 		 * tdq_notify().
 		 */
 		if (tdq->tdq_load == 0) {
+			switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
 			tdq->tdq_idlestate = TDQ_IDLE;
 			if (tdq->tdq_load == 0)
-				cpu_idle();
+				cpu_idle(switchcnt > 1);
 		}
 		if (tdq->tdq_load) {
 			thread_lock(td);