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

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Date:   Wed, 14 Nov 2018 03:46:06 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yauheni Kaliuta <yauheni.kaliuta@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, Rik van Riel <riel@...hat.com>
Subject: [PATCH 22/25] cpufreq: Use vtime aware kcpustat accessor

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@...hat.com>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Rik van Riel <riel@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Wanpeng Li <wanpengli@...cent.com>
Cc: Ingo Molnar <mingo@...nel.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