From 679b8fe43a6b723787cae1d9599ed776d7ce238b Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 15 Feb 2016 02:15:50 +0100 Subject: [PATCH] cpufreq: governor: Fix nice contribution computation in dbs_check_cpu() The contribution of the CPU nice time to the idle time in dbs_check_cpu() is computed in a bogus way, as the code may subtract current and previous nice values for different CPUs. That doesn't matter for cases when cpufreq policies are not shared, but may lead to problems otherwise. Fix the computation and simplify it to avoid taking unnecessary steps. Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar --- drivers/cpufreq/cpufreq_governor.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index e5a08a13ca84..c5469701a3ef 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -198,22 +198,10 @@ void dbs_check_cpu(struct cpufreq_policy *policy) j_cdbs->prev_cpu_idle = cur_idle_time; if (ignore_nice) { - struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(cpu); - u64 cur_nice; - unsigned long cur_nice_jiffies; + u64 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; - cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] - - cdbs->prev_cpu_nice; - /* - * Assumption: nice time between sampling periods will - * be less than 2^32 jiffies for 32 bit sys - */ - cur_nice_jiffies = (unsigned long) - cputime64_to_jiffies64(cur_nice); - - cdbs->prev_cpu_nice = - kcpustat_cpu(j).cpustat[CPUTIME_NICE]; - idle_time += jiffies_to_usecs(cur_nice_jiffies); + idle_time += cputime_to_usecs(cur_nice - j_cdbs->prev_cpu_nice); + j_cdbs->prev_cpu_nice = cur_nice; } if (unlikely(!wall_time || wall_time < idle_time))