[CPUFREQ][4/6] cpufreq_ondemand: Parameterize down differential

Use a parameter for down differential, instead of hardcoded 10%. Follow-on
patch changes the down-differential dynamically, based on whether
we are using idle micro-accounting or not.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index b935092aab21..3f898606e68c 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -24,6 +24,7 @@
  * It helps to keep variable names smaller, simpler
  */
 
+#define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
@@ -86,10 +87,12 @@ static struct workqueue_struct	*kondemand_wq;
 static struct dbs_tuners {
         unsigned int sampling_rate;
         unsigned int up_threshold;
+        unsigned int down_differential;
         unsigned int ignore_nice;
         unsigned int powersave_bias;
 } dbs_tuners_ins = {
         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
+        .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
         .ignore_nice = 0,
         .powersave_bias = 0,
 };
@@ -424,9 +427,13 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
          * can support the current CPU usage without triggering the up
          * policy. To be safe, we focus 10 points under the threshold.
          */
-        if (max_load_freq < (dbs_tuners_ins.up_threshold - 10) * policy->cur) {
+        if (max_load_freq <
+            (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
+             policy->cur) {
                 unsigned int freq_next;
-                freq_next = max_load_freq / (dbs_tuners_ins.up_threshold - 10);
+                freq_next = max_load_freq /
+                                (dbs_tuners_ins.up_threshold -
+                                 dbs_tuners_ins.down_differential);
 
                 if (!dbs_tuners_ins.powersave_bias) {
                         __cpufreq_driver_target(policy, freq_next,