Merge branch 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/roland/infiniband

[pandora-kernel.git] / drivers / cpufreq / cpufreq_ondemand.c

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index c1fc9c6..1774111 100644 (file)
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -48,7 +48,10 @@
  * All times here are in uS.
  */
 static unsigned int                            def_sampling_rate;
-#define MIN_SAMPLING_RATE                      (def_sampling_rate / 2)
+#define MIN_SAMPLING_RATE_RATIO                        (2)
+/* for correct statistics, we need at least 10 ticks between each measure */
+#define MIN_STAT_SAMPLING_RATE                 (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
+#define MIN_SAMPLING_RATE                      (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
 #define MAX_SAMPLING_RATE                      (500 * def_sampling_rate)
 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER   (1000)
 #define DEF_SAMPLING_DOWN_FACTOR               (1)
@@ -416,13 +419,16 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                if (dbs_enable == 1) {
                        unsigned int latency;
                        /* policy latency is in nS. Convert it to uS first */
+                       latency = policy->cpuinfo.transition_latency / 1000;
+                       if (latency == 0)
+                               latency = 1;
 
-                       latency = policy->cpuinfo.transition_latency;
-                       if (latency < 1000)
-                               latency = 1000;
-
-                       def_sampling_rate = (latency / 1000) *
+                       def_sampling_rate = latency *
                                        DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
+
+                       if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
+                               def_sampling_rate = MIN_STAT_SAMPLING_RATE;
+
                        dbs_tuners_ins.sampling_rate = def_sampling_rate;
                        dbs_tuners_ins.ignore_nice = 0;