---

yaml
---
r: 37613
b: refs/heads/master
c: 5c87579
h: refs/heads/master
i:
  37611: d09fa25
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 130c6b98984a058068ea595c465fba2beb48b9ef
+refs/heads/master: 5c87579e65ee4f419b2369407f82326d38b5d2d8

trunk/drivers/acpi/processor_idle.c

@@ -38,6 +38,7 @@
 #include <linux/dmi.h>
 #include <linux/moduleparam.h>
 #include <linux/sched.h>	/* need_resched() */
+#include <linux/latency.h>
 
 #include <asm/io.h>
 #include <asm/uaccess.h>
@@ -453,7 +454,8 @@ static void acpi_processor_idle(void)
 	 */
 	if (cx->promotion.state &&
 	    ((cx->promotion.state - pr->power.states) <= max_cstate)) {
-		if (sleep_ticks > cx->promotion.threshold.ticks) {
+		if (sleep_ticks > cx->promotion.threshold.ticks &&
+		  cx->promotion.state->latency <= system_latency_constraint()) {
 			cx->promotion.count++;
 			cx->demotion.count = 0;
 			if (cx->promotion.count >=
@@ -494,8 +496,10 @@ static void acpi_processor_idle(void)
       end:
 	/*
 	 * Demote if current state exceeds max_cstate
+	 * or if the latency of the current state is unacceptable
 	 */
-	if ((pr->power.state - pr->power.states) > max_cstate) {
+	if ((pr->power.state - pr->power.states) > max_cstate ||
+		pr->power.state->latency > system_latency_constraint()) {
 		if (cx->demotion.state)
 			next_state = cx->demotion.state;
 	}
@@ -1009,9 +1013,11 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
 
 	seq_printf(seq, "active state:            C%zd\n"
 		   "max_cstate:              C%d\n"
-		   "bus master activity:     %08x\n",
+		   "bus master activity:     %08x\n"
+		   "maximum allowed latency: %d usec\n",
 		   pr->power.state ? pr->power.state - pr->power.states : 0,
-		   max_cstate, (unsigned)pr->power.bm_activity);
+		   max_cstate, (unsigned)pr->power.bm_activity,
+		   system_latency_constraint());
 
 	seq_puts(seq, "states:\n");
 
@@ -1077,6 +1083,28 @@ static const struct file_operations acpi_processor_power_fops = {
 	.release = single_release,
 };
 
+static void smp_callback(void *v)
+{
+	/* we already woke the CPU up, nothing more to do */
+}
+
+/*
+ * This function gets called when a part of the kernel has a new latency
+ * requirement.  This means we need to get all processors out of their C-state,
+ * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
+ * wakes them all right up.
+ */
+static int acpi_processor_latency_notify(struct notifier_block *b,
+		unsigned long l, void *v)
+{
+	smp_call_function(smp_callback, NULL, 0, 1);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block acpi_processor_latency_notifier = {
+	.notifier_call = acpi_processor_latency_notify,
+};
+
 int acpi_processor_power_init(struct acpi_processor *pr,
 			      struct acpi_device *device)
 {
@@ -1093,6 +1121,7 @@ int acpi_processor_power_init(struct acpi_processor *pr,
 			       "ACPI: processor limited to max C-state %d\n",
 			       max_cstate);
 		first_run++;
+		register_latency_notifier(&acpi_processor_latency_notifier);
 	}
 
 	if (!pr)
@@ -1164,6 +1193,7 @@ int acpi_processor_power_exit(struct acpi_processor *pr,
 		 * copies of pm_idle before proceeding.
 		 */
 		cpu_idle_wait();
+		unregister_latency_notifier(&acpi_processor_latency_notifier);
 	}
 
 	return 0;

trunk/drivers/net/wireless/ipw2100.c

@@ -163,6 +163,7 @@ that only one external action is invoked at a time.
 #include <linux/firmware.h>
 #include <linux/acpi.h>
 #include <linux/ctype.h>
+#include <linux/latency.h>
 
 #include "ipw2100.h"
 
@@ -1697,6 +1698,11 @@ static int ipw2100_up(struct ipw2100_priv *priv, int deferred)
 		return 0;
 	}
 
+	/* the ipw2100 hardware really doesn't want power management delays
+	 * longer than 175usec
+	 */
+	modify_acceptable_latency("ipw2100", 175);
+
 	/* If the interrupt is enabled, turn it off... */
 	spin_lock_irqsave(&priv->low_lock, flags);
 	ipw2100_disable_interrupts(priv);
@@ -1849,6 +1855,8 @@ static void ipw2100_down(struct ipw2100_priv *priv)
 	ipw2100_disable_interrupts(priv);
 	spin_unlock_irqrestore(&priv->low_lock, flags);
 
+	modify_acceptable_latency("ipw2100", INFINITE_LATENCY);
+
 #ifdef ACPI_CSTATE_LIMIT_DEFINED
 	if (priv->config & CFG_C3_DISABLED) {
 		IPW_DEBUG_INFO(": Resetting C3 transitions.\n");
@@ -6534,6 +6542,7 @@ static int __init ipw2100_init(void)
 
 	ret = pci_register_driver(&ipw2100_pci_driver);
 
+	set_acceptable_latency("ipw2100", INFINITE_LATENCY);
 #ifdef CONFIG_IPW2100_DEBUG
 	ipw2100_debug_level = debug;
 	driver_create_file(&ipw2100_pci_driver.driver,
@@ -6554,6 +6563,7 @@ static void __exit ipw2100_exit(void)
 			   &driver_attr_debug_level);
 #endif
 	pci_unregister_driver(&ipw2100_pci_driver);
+	remove_acceptable_latency("ipw2100");
 }
 
 module_init(ipw2100_init);

trunk/include/linux/latency.h

@@ -0,0 +1,25 @@
+/*
+ * latency.h: Explicit system-wide latency-expectation infrastructure
+ *
+ * (C) Copyright 2006 Intel Corporation
+ * Author: Arjan van de Ven <arjan@linux.intel.com>
+ *
+ */
+
+#ifndef _INCLUDE_GUARD_LATENCY_H_
+#define _INCLUDE_GUARD_LATENCY_H_
+
+#include <linux/notifier.h>
+
+void set_acceptable_latency(char *identifier, int usecs);
+void modify_acceptable_latency(char *identifier, int usecs);
+void remove_acceptable_latency(char *identifier);
+void synchronize_acceptable_latency(void);
+int system_latency_constraint(void);
+
+int register_latency_notifier(struct notifier_block * nb);
+int unregister_latency_notifier(struct notifier_block * nb);
+
+#define INFINITE_LATENCY 1000000
+
+#endif

trunk/kernel/Makefile

@@ -8,7 +8,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 	    signal.o sys.o kmod.o workqueue.o pid.o \
 	    rcupdate.o extable.o params.o posix-timers.o \
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
-	    hrtimer.o rwsem.o
+	    hrtimer.o rwsem.o latency.o
 
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/