[PATCH 22/25] cpufreq: Use vtime aware kcpustat accessor

Frederic Weisbecker
2018-11-14T02:47:09Z

Now that we have a vtime safe kcpustat accessor, use it to fix frozen
kcpustat values on nohz_full CPUs.

Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Ingo Molnar <mingo@kernel.org>
---
drivers/cpufreq/cpufreq.c | 18 +++++++++++-------
drivers/cpufreq/cpufreq_governor.c | 27 ++++++++++++++++++++-------
2 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 7aa3dca..e9cff3f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -119,18 +119,22 @@ EXPORT_SYMBOL_GPL(get_governor_parent_kobj);

static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
{
- u64 idle_time;
+ struct kernel_cpustat *kcpustat = &kcpustat_cpu(cpu);
+ u64 user, nice, sys, guest, guest_nice;
u64 cur_wall_time;
+ u64 idle_time;
u64 busy_time;

cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());

- busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
- busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
- busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
- busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
- busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
- busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
+ kcpustat_cputime(kcpustat, cpu, &user, &nice, &sys,
+ &guest, &guest_nice);
+ busy_time = user;
+ busy_time += sys;
+ busy_time += kcpustat->cpustat[CPUTIME_IRQ];
+ busy_time += kcpustat->cpustat[CPUTIME_SOFTIRQ];
+ busy_time += kcpustat->cpustat[CPUTIME_STEAL];
+ busy_time += nice;

idle_time = cur_wall_time - busy_time;
if (wall)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 6d53f7d..5ebe726 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -107,8 +107,13 @@ void gov_update_cpu_data(struct dbs_data *dbs_data)

j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time,
dbs_data->io_is_busy);
- if (dbs_data->ignore_nice_load)
- j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+ if (dbs_data->ignore_nice_load) {
+ u64 user, nice, sys, guest, guest_nice;
+
+ kcpustat_cputime(&kcpustat_cpu(j), j, &user, &nice, &sys,
+ &guest, &guest_nice);
+ j_cdbs->prev_cpu_nice = nice;
+ }
}
}
}
@@ -152,10 +157,13 @@ unsigned int dbs_update(struct cpufreq_policy *policy)
j_cdbs->prev_cpu_idle = cur_idle_time;

if (ignore_nice) {
- u64 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+ u64 user, nice, sys, guest, guest_nice;

- idle_time += div_u64(cur_nice - j_cdbs->prev_cpu_nice, NSEC_PER_USEC);
- j_cdbs->prev_cpu_nice = cur_nice;
+ kcpustat_cputime(&kcpustat_cpu(j), j, &user, &nice, &sys,
+ &guest, &guest_nice);
+
+ idle_time += div_u64(nice - j_cdbs->prev_cpu_nice, NSEC_PER_USEC);
+ j_cdbs->prev_cpu_nice = nice;
}

if (unlikely(!time_elapsed)) {
@@ -530,8 +538,13 @@ int cpufreq_dbs_governor_start(struct cpufreq_policy *policy)
*/
j_cdbs->prev_load = 0;

- if (ignore_nice)
- j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+ if (ignore_nice) {
+ u64 user, nice, sys, guest, guest_nice;
+
+ kcpustat_cputime(&kcpustat_cpu(j), j, &user, &nice, &sys,
+ &guest, &guest_nice);
+ j_cdbs->prev_cpu_nice = nice;
+ }
}

gov->start(policy);
--
2.7.4