| Message ID | 4591302.DXuxEtjCGY@vostro.rjw.lan (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On 15-02-16, 02:15, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > 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 <rafael.j.wysocki@intel.com> > --- > drivers/cpufreq/cpufreq_governor.c | 18 +++--------------- > 1 file changed, 3 insertions(+), 15 deletions(-) Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Index: linux-pm/drivers/cpufreq/cpufreq_governor.c =================================================================== --- linux-pm.orig/drivers/cpufreq/cpufreq_governor.c +++ linux-pm/drivers/cpufreq/cpufreq_governor.c @@ -198,22 +198,10 @@ void dbs_check_cpu(struct cpufreq_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))