[PATCH 3/4] sched/cpuacct: fix user/system in shown cpuacct.usage*
From: Andrey Ryabinin
Date: Wed Feb 17 2021 - 07:08:11 EST
cpuacct has 2 different ways of accounting and showing user
and system times.
The first one uses cpuacct_account_field() to account times
and cpuacct.stat file to expose them. And this one seems to work ok.
The second one is uses cpuacct_charge() function for accounting and
set of cpuacct.usage* files to show times. Despite some attempts to
fix it in the past it still doesn't work. E.g. while running KVM
guest the cpuacct_charge() accounts most of the guest time as
system time. This doesn't match with user&system times shown in
cpuacct.stat or proc/<pid>/stat.
Use cpustats accounted in cpuacct_account_field() as the source
of user/sys times for cpuacct.usage* files. Make cpuacct_charge()
to account only summary execution time.
Fixes: d740037fac70 ("sched/cpuacct: Split usage accounting into user_usage and sys_usage")
Signed-off-by: Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
kernel/sched/cpuacct.c | 77 +++++++++++++++++++-----------------------
1 file changed, 34 insertions(+), 43 deletions(-)
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 941c28cf9738..7eff79faab0d 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -29,7 +29,7 @@ struct cpuacct_usage {
struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every CPU */
- struct cpuacct_usage __percpu *cpuusage;
+ u64 __percpu *cpuusage;
struct kernel_cpustat __percpu *cpustat;
};
@@ -49,7 +49,7 @@ static inline struct cpuacct *parent_ca(struct cpuacct *ca)
return css_ca(ca->css.parent);
}
-static DEFINE_PER_CPU(struct cpuacct_usage, root_cpuacct_cpuusage);
+static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
static struct cpuacct root_cpuacct = {
.cpustat = &kernel_cpustat,
.cpuusage = &root_cpuacct_cpuusage,
@@ -68,7 +68,7 @@ cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
if (!ca)
goto out;
- ca->cpuusage = alloc_percpu(struct cpuacct_usage);
+ ca->cpuusage = alloc_percpu(u64);
if (!ca->cpuusage)
goto out_free_ca;
@@ -99,7 +99,8 @@ static void cpuacct_css_free(struct cgroup_subsys_state *css)
static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
enum cpuacct_stat_index index)
{
- struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
+ u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
+ u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
u64 data;
/*
@@ -115,14 +116,17 @@ static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
raw_spin_lock_irq(&cpu_rq(cpu)->lock);
#endif
- if (index == CPUACCT_STAT_NSTATS) {
- int i = 0;
-
- data = 0;
- for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
- data += cpuusage->usages[i];
- } else {
- data = cpuusage->usages[index];
+ switch (index) {
+ case CPUACCT_STAT_USER:
+ data = cpustat[CPUTIME_USER] + cpustat[CPUTIME_NICE];
+ break;
+ case CPUACCT_STAT_SYSTEM:
+ data = cpustat[CPUTIME_SYSTEM] + cpustat[CPUTIME_IRQ] +
+ cpustat[CPUTIME_SOFTIRQ];
+ break;
+ case CPUACCT_STAT_NSTATS:
+ data = *cpuusage;
+ break;
}
#ifndef CONFIG_64BIT
@@ -132,10 +136,14 @@ static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu,
return data;
}
-static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
+static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu)
{
- struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
- int i;
+ u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
+ u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
+
+ /* Don't allow to reset global kernel_cpustat */
+ if (ca == &root_cpuacct)
+ return;
#ifndef CONFIG_64BIT
/*
@@ -143,9 +151,10 @@ static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
*/
raw_spin_lock_irq(&cpu_rq(cpu)->lock);
#endif
-
- for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
- cpuusage->usages[i] = val;
+ *cpuusage = 0;
+ cpustat[CPUTIME_USER] = cpustat[CPUTIME_NICE] = 0;
+ cpustat[CPUTIME_SYSTEM] = cpustat[CPUTIME_IRQ] = 0;
+ cpustat[CPUTIME_SOFTIRQ] = 0;
#ifndef CONFIG_64BIT
raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
@@ -196,7 +205,7 @@ static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
return -EINVAL;
for_each_possible_cpu(cpu)
- cpuacct_cpuusage_write(ca, cpu, 0);
+ cpuacct_cpuusage_write(ca, cpu);
return 0;
}
@@ -243,25 +252,12 @@ static int cpuacct_all_seq_show(struct seq_file *m, void *V)
seq_puts(m, "\n");
for_each_possible_cpu(cpu) {
- struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
-
seq_printf(m, "%d", cpu);
- for (index = 0; index < CPUACCT_STAT_NSTATS; index++) {
-#ifndef CONFIG_64BIT
- /*
- * Take rq->lock to make 64-bit read safe on 32-bit
- * platforms.
- */
- raw_spin_lock_irq(&cpu_rq(cpu)->lock);
-#endif
-
- seq_printf(m, " %llu", cpuusage->usages[index]);
+ for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
+ seq_printf(m, " %llu",
+ cpuacct_cpuusage_read(ca, cpu, index));
-#ifndef CONFIG_64BIT
- raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
-#endif
- }
seq_puts(m, "\n");
}
return 0;
@@ -278,8 +274,8 @@ static int cpuacct_stats_show(struct seq_file *sf, void *v)
for_each_possible_cpu(cpu) {
u64 *cpustat = per_cpu_ptr(ca->cpustat, cpu)->cpustat;
- val[CPUACCT_STAT_USER] += cpustat[CPUTIME_USER];
- val[CPUACCT_STAT_USER] += cpustat[CPUTIME_NICE];
+ val[CPUACCT_STAT_USER] += cpustat[CPUTIME_USER];
+ val[CPUACCT_STAT_USER] += cpustat[CPUTIME_NICE];
val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SYSTEM];
val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_IRQ];
val[CPUACCT_STAT_SYSTEM] += cpustat[CPUTIME_SOFTIRQ];
@@ -339,16 +335,11 @@ static struct cftype files[] = {
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
- int index = CPUACCT_STAT_SYSTEM;
- struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);
-
- if (regs && user_mode(regs))
- index = CPUACCT_STAT_USER;
rcu_read_lock();
for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
- __this_cpu_add(ca->cpuusage->usages[index], cputime);
+ __this_cpu_add(*ca->cpuusage, cputime);
rcu_read_unlock();
}
--
2.26.2