Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits)
  stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback()
  sched, wait: Use wrapper functions
  sched: Remove a stale comment
  ondemand: Make the iowait-is-busy time a sysfs tunable
  ondemand: Solve a big performance issue by counting IOWAIT time as busy
  sched: Intoduce get_cpu_iowait_time_us()
  sched: Eliminate the ts->idle_lastupdate field
  sched: Fold updating of the last_update_time_info into update_ts_time_stats()
  sched: Update the idle statistics in get_cpu_idle_time_us()
  sched: Introduce a function to update the idle statistics
  sched: Add a comment to get_cpu_idle_time_us()
  cpu_stop: add dummy implementation for UP
  sched: Remove rq argument to the tracepoints
  rcu: need barrier() in UP synchronize_sched_expedited()
  sched: correctly place paranioa memory barriers in synchronize_sched_expedited()
  sched: kill paranoia check in synchronize_sched_expedited()
  sched: replace migration_thread with cpu_stop
  stop_machine: reimplement using cpu_stop
  cpu_stop: implement stop_cpu[s]()
  sched: Fix select_idle_sibling() logic in select_task_rq_fair()
  ...

2 files changed, 75 insertions, 14 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index bd444dc93cf2..8e9dbdc6c700 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -73,6 +73,7 @@ enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
 
 struct cpu_dbs_info_s {
         cputime64_t prev_cpu_idle;
+        cputime64_t prev_cpu_iowait;
         cputime64_t prev_cpu_wall;
         cputime64_t prev_cpu_nice;
         struct cpufreq_policy *cur_policy;
@@ -108,6 +109,7 @@ static struct dbs_tuners {
         unsigned int down_differential;
         unsigned int ignore_nice;
         unsigned int powersave_bias;
+        unsigned int io_is_busy;
 } dbs_tuners_ins = {
         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
@@ -148,6 +150,16 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
         return idle_time;
 }
 
+static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
+{
+        u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
+
+        if (iowait_time == -1ULL)
+                return 0;
+
+        return iowait_time;
+}
+
 /*
  * Find right freq to be set now with powersave_bias on.
  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
@@ -249,6 +261,7 @@ static ssize_t show_##file_name						\
         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 }
 show_one(sampling_rate, sampling_rate);
+show_one(io_is_busy, io_is_busy);
 show_one(up_threshold, up_threshold);
 show_one(ignore_nice_load, ignore_nice);
 show_one(powersave_bias, powersave_bias);
@@ -299,6 +312,23 @@ static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
         return count;
 }
 
+static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
+                                   const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+
+        ret = sscanf(buf, "%u", &input);
+        if (ret != 1)
+                return -EINVAL;
+
+        mutex_lock(&dbs_mutex);
+        dbs_tuners_ins.io_is_busy = !!input;
+        mutex_unlock(&dbs_mutex);
+
+        return count;
+}
+
 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
                                   const char *buf, size_t count)
 {
@@ -381,6 +411,7 @@ static struct global_attr _name = \
 __ATTR(_name, 0644, show_##_name, store_##_name)
 
 define_one_rw(sampling_rate);
+define_one_rw(io_is_busy);
 define_one_rw(up_threshold);
 define_one_rw(ignore_nice_load);
 define_one_rw(powersave_bias);
@@ -392,6 +423,7 @@ static struct attribute *dbs_attributes[] = {
         &up_threshold.attr,
         &ignore_nice_load.attr,
         &powersave_bias.attr,
+        &io_is_busy.attr,
         NULL
 };
 
@@ -470,14 +502,15 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 
         for_each_cpu(j, policy->cpus) {
                 struct cpu_dbs_info_s *j_dbs_info;
-                cputime64_t cur_wall_time, cur_idle_time;
-                unsigned int idle_time, wall_time;
+                cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
+                unsigned int idle_time, wall_time, iowait_time;
                 unsigned int load, load_freq;
                 int freq_avg;
 
                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 
                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
+                cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
 
                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
                                 j_dbs_info->prev_cpu_wall);
@@ -487,6 +520,10 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                                 j_dbs_info->prev_cpu_idle);
                 j_dbs_info->prev_cpu_idle = cur_idle_time;
 
+                iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
+                                j_dbs_info->prev_cpu_iowait);
+                j_dbs_info->prev_cpu_iowait = cur_iowait_time;
+
                 if (dbs_tuners_ins.ignore_nice) {
                         cputime64_t cur_nice;
                         unsigned long cur_nice_jiffies;
@@ -504,6 +541,16 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
                 }
 
+                /*
+                 * For the purpose of ondemand, waiting for disk IO is an
+                 * indication that you're performance critical, and not that
+                 * the system is actually idle. So subtract the iowait time
+                 * from the cpu idle time.
+                 */
+
+                if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
+                        idle_time -= iowait_time;
+
                 if (unlikely(!wall_time || wall_time < idle_time))
                         continue;
 
@@ -617,6 +664,29 @@ static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
         cancel_delayed_work_sync(&dbs_info->work);
 }
 
+/*
+ * Not all CPUs want IO time to be accounted as busy; this dependson how
+ * efficient idling at a higher frequency/voltage is.
+ * Pavel Machek says this is not so for various generations of AMD and old
+ * Intel systems.
+ * Mike Chan (androidlcom) calis this is also not true for ARM.
+ * Because of this, whitelist specific known (series) of CPUs by default, and
+ * leave all others up to the user.
+ */
+static int should_io_be_busy(void)
+{
+#if defined(CONFIG_X86)
+        /*
+         * For Intel, Core 2 (model 15) andl later have an efficient idle.
+         */
+        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+            boot_cpu_data.x86 == 6 &&
+            boot_cpu_data.x86_model >= 15)
+                return 1;
+#endif
+        return 0;
+}
+
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                                    unsigned int event)
 {
@@ -679,6 +749,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         dbs_tuners_ins.sampling_rate =
                                 max(min_sampling_rate,
                                     latency * LATENCY_MULTIPLIER);
+                        dbs_tuners_ins.io_is_busy = should_io_be_busy();
                 }
                 mutex_unlock(&dbs_mutex);
 
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 2ac4440e7b08..8943b8ccee1a 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -80,12 +80,6 @@ static void do_suspend(void)
 
         shutting_down = SHUTDOWN_SUSPEND;
 
-        err = stop_machine_create();
-        if (err) {
-                printk(KERN_ERR "xen suspend: failed to setup stop_machine %d\n", err);
-                goto out;
-        }
-
 #ifdef CONFIG_PREEMPT
         /* If the kernel is preemptible, we need to freeze all the processes
            to prevent them from being in the middle of a pagetable update
@@ -93,7 +87,7 @@ static void do_suspend(void)
         err = freeze_processes();
         if (err) {
                 printk(KERN_ERR "xen suspend: freeze failed %d\n", err);
-                goto out_destroy_sm;
+                goto out;
         }
 #endif
 
@@ -136,12 +130,8 @@ out_resume:
 out_thaw:
 #ifdef CONFIG_PREEMPT
         thaw_processes();
-
-out_destroy_sm:
-#endif
-        stop_machine_destroy();
-
 out:
+#endif
         shutting_down = SHUTDOWN_INVALID;
 }
 #endif  /* CONFIG_PM_SLEEP */