cpufreq: interactive: reduce chance of zero time delta on load eval

Reschedule load sampling timer after timestamp of sample start taken,
hold spinlock across entire sequence to avoid preemption.  Avoid the
WARN for zero time delta in the load sampling timer function.

Change-Id: Idc10a756f09141decb6df92669521a1ebf0dbc10
Signed-off-by: Todd Poynor <toddpoynor@google.com>

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 1b5d9301e2d7812b41e4b85ab535a9faa2e3ad14..b4d12b266c648d44fb6e4b7faaa6f13b29f20339 100644 (file)
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -169,21 +169,23 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu,
 static void cpufreq_interactive_timer_resched(
        struct cpufreq_interactive_cpuinfo *pcpu)
 {
-       unsigned long expires = jiffies + usecs_to_jiffies(timer_rate);
+       unsigned long expires;
        unsigned long flags;
 
-       mod_timer_pinned(&pcpu->cpu_timer, expires);
-       if (timer_slack_val >= 0 && pcpu->target_freq > pcpu->policy->min) {
-               expires += usecs_to_jiffies(timer_slack_val);
-               mod_timer_pinned(&pcpu->cpu_slack_timer, expires);
-       }
-
        spin_lock_irqsave(&pcpu->load_lock, flags);
        pcpu->time_in_idle =
                get_cpu_idle_time(smp_processor_id(),
                                     &pcpu->time_in_idle_timestamp);
        pcpu->cputime_speedadj = 0;
        pcpu->cputime_speedadj_timestamp = pcpu->time_in_idle_timestamp;
+       expires = jiffies + usecs_to_jiffies(timer_rate);
+       mod_timer_pinned(&pcpu->cpu_timer, expires);
+
+       if (timer_slack_val >= 0 && pcpu->target_freq > pcpu->policy->min) {
+               expires += usecs_to_jiffies(timer_slack_val);
+               mod_timer_pinned(&pcpu->cpu_slack_timer, expires);
+       }
+
        spin_unlock_irqrestore(&pcpu->load_lock, flags);
 }