Index: acpi_cpu.c
===================================================================
RCS file: /home/FreeBSD/ncvs/src/sys/dev/acpica/acpi_cpu.c,v
retrieving revision 1.63
diff -u -r1.63 acpi_cpu.c
--- acpi_cpu.c	23 Jan 2007 07:20:44 -0000	1.63
+++ acpi_cpu.c	13 Feb 2007 03:28:32 -0000
@@ -80,6 +80,7 @@
     /* Runtime state. */
     int			 cpu_non_c3;	/* Index of lowest non-C3 state. */
     int			 cpu_short_slp;	/* Count of < 1us sleeps. */
+    int			 cpu_long_slp;	/* Count of > hz sleeps. */
     u_int		 cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */
     /* Values for sysctl. */
     struct sysctl_ctx_list cpu_sysctl_ctx;
@@ -123,6 +124,9 @@
 static int		 cpu_disable_idle; /* Disable entry to idle function */
 static int		 cpu_cx_count;	/* Number of valid Cx states */
 
+/* Longest allowable sleep */
+static int		 cpu_max_sleep = 0;
+
 /* Values for sysctl. */
 static struct sysctl_ctx_list cpu_sysctl_ctx;
 static struct sysctl_oid *cpu_sysctl_tree;
@@ -278,6 +282,9 @@
     cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
     cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
 
+    sc->cpu_short_slp = 0;
+    sc->cpu_long_slp = 0;
+
     buf.Pointer = NULL;
     buf.Length = ACPI_ALLOCATE_BUFFER;
     status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
@@ -311,6 +318,10 @@
 
 	/* Queue post cpu-probing task handler */
 	AcpiOsQueueForExecution(OSD_PRIORITY_LO, acpi_cpu_startup, NULL);
+
+	/* Setup the longest allowable sleep */
+	cpu_max_sleep = 1000000 / hz;
+	cpu_max_sleep *= 10;
     }
 
     /*
@@ -832,10 +843,17 @@
 	 * that both cores will get out of C3 state as soon as one of them
 	 * requires it. This breaks the sleep detection logic as the sleep
 	 * counter is local to each cpu. Disable the sleep logic for now as a
-	 * workaround if there's more than one CPU. The right fix would probably
-	 * be to add quirks for system that don't really support C3 state.
+	 * workaround if we have more than one cpus and some of them are.
+	 * logical (more than one core per package). The right fix would
+	 * probably be to add quirks for system that don't really support
+	 * C3 state.
 	 */
-	if (mp_ncpus < 2 && sc->cpu_prev_sleep <= 1) {
+#ifdef SMP
+	if (((mp_ncpus >= 2 && logical_cpus_mask == 0) || mp_ncpus < 2)
+	    && sc->cpu_prev_sleep <= 1) {  
+#else
+	if (sc->cpu_prev_sleep <= 1) {
+#endif
 	    sc->cpu_short_slp++;
 	    if (sc->cpu_short_slp == 1000 && sc->cpu_cx_lowest != 0) {
 		if (sc->cpu_non_c3 == sc->cpu_cx_lowest && sc->cpu_non_c3 != 0)
@@ -849,6 +867,26 @@
 	} else
 	    sc->cpu_short_slp = 0;
 
+	/*
+	 * If we keep sleeping for more than 1 hz it may indicate a broken
+	 * system where the clock will not fire anymore in low Cx states.
+	 * Keep backing off in this case until we start getting back clock
+	 * interrupts.
+	 */
+	if (sc->cpu_prev_sleep > cpu_max_sleep) {
+	    sc->cpu_long_slp++;
+	    if (sc->cpu_long_slp == 10 && sc->cpu_cx_lowest != 0) {
+		if (sc->cpu_non_c3 == sc->cpu_cx_lowest && sc->cpu_non_c3 != 0)
+		    sc->cpu_non_c3--;
+		sc->cpu_cx_lowest--;
+		sc->cpu_long_slp = 0;
+		device_printf(sc->cpu_dev,
+		    "too many long sleeps, backing off to C%d\n",
+		    sc->cpu_cx_lowest + 1);
+	    }
+	} else
+	    sc->cpu_long_slp = 0;
+
 	for (i = sc->cpu_cx_lowest; i >= 0; i--)
 	    if (sc->cpu_cx_states[i].trans_lat <= sc->cpu_prev_sleep) {
 		cx_next_idx = i;