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Subject[PATCH 2/2] sched/core: Uncookied force idle accounting per cpu
Date
Forced idle can be divided into two types, forced idle with cookie'd task
running on it SMT sibling, and forced idle with uncookie'd task running
on it SMT sibling, which should be accounting to measure the cost of
enabling core scheduling too.

This patch accounts the forced idle time with uncookie'd task, and the
sum of both.

A few details:
- Uncookied forceidle time and total forceidle time is displayed via
the last two columns of /proc/stat.
- Uncookied forceidle time is ony accounted when this cpu is forced
idle and a sibling hyperthread is running with an uncookie'd task.

Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
---
fs/proc/stat.c | 13 ++++++++++++-
include/linux/kernel_stat.h | 1 +
kernel/sched/core.c | 3 +--
kernel/sched/core_sched.c | 7 ++++---
4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 3a2fbc9..21607cf 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -110,7 +110,7 @@ static int show_stat(struct seq_file *p, void *v)
int i, j;
u64 user, nice, system, idle, iowait, irq, softirq, steal;
#ifdef CONFIG_SCHED_CORE
- u64 cookied_forceidle = 0;
+ u64 cookied_forceidle, uncookied_forceidle, forceidle;
#endif
u64 guest, guest_nice;
u64 sum = 0;
@@ -121,6 +121,9 @@ static int show_stat(struct seq_file *p, void *v)
user = nice = system = idle = iowait =
irq = softirq = steal = 0;
guest = guest_nice = 0;
+#ifdef CONFIG_SCHED_CORE
+ cookied_forceidle = uncookied_forceidle = forceidle = 0;
+#endif
getboottime64(&boottime);
/* shift boot timestamp according to the timens offset */
timens_sub_boottime(&boottime);
@@ -145,6 +148,8 @@ static int show_stat(struct seq_file *p, void *v)
sum += arch_irq_stat_cpu(i);
#ifdef CONFIG_SCHED_CORE
cookied_forceidle += cpustat[CPUTIME_COOKIED_FORCEIDLE];
+ uncookied_forceidle += cpustat[CPUTIME_UNCOOKIED_FORCEIDLE];
+ forceidle = cookied_forceidle + uncookied_forceidle;
#endif

for (j = 0; j < NR_SOFTIRQS; j++) {
@@ -168,6 +173,8 @@ static int show_stat(struct seq_file *p, void *v)
seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
#ifdef CONFIG_SCHED_CORE
seq_put_decimal_ull(p, " ", nsec_to_clock_t(cookied_forceidle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(uncookied_forceidle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(forceidle));
#endif
seq_putc(p, '\n');

@@ -190,6 +197,8 @@ static int show_stat(struct seq_file *p, void *v)
guest_nice = cpustat[CPUTIME_GUEST_NICE];
#ifdef CONFIG_SCHED_CORE
cookied_forceidle = cpustat[CPUTIME_COOKIED_FORCEIDLE];
+ uncookied_forceidle = cpustat[CPUTIME_UNCOOKIED_FORCEIDLE];
+ forceidle = cookied_forceidle + uncookied_forceidle;
#endif
seq_printf(p, "cpu%d", i);
seq_put_decimal_ull(p, " ", nsec_to_clock_t(user));
@@ -204,6 +213,8 @@ static int show_stat(struct seq_file *p, void *v)
seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
#ifdef CONFIG_SCHED_CORE
seq_put_decimal_ull(p, " ", nsec_to_clock_t(cookied_forceidle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(uncookied_forceidle));
+ seq_put_decimal_ull(p, " ", nsec_to_clock_t(forceidle));
#endif
seq_putc(p, '\n');
}
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index a21b065..23945c1 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -30,6 +30,7 @@ enum cpu_usage_stat {
CPUTIME_GUEST_NICE,
#ifdef CONFIG_SCHED_CORE
CPUTIME_COOKIED_FORCEIDLE,
+ CPUTIME_UNCOOKIED_FORCEIDLE,
#endif
NR_STATS,
};
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f4f4b24..16d937e4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5822,8 +5822,7 @@ static inline struct task_struct *pick_task(struct rq *rq)
}

if (rq->core->core_forceidle_count) {
- if (cookie)
- rq->core->core_forceidle_start = rq_clock(rq->core);
+ rq->core->core_forceidle_start = rq_clock(rq->core);
rq->core->core_forceidle_occupation = occ;
}

diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
index bc5f45f..89bd49d 100644
--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -265,11 +265,12 @@ void sched_core_account_forceidle(struct rq *rq)
rq_i = cpu_rq(i);
p = rq_i->core_pick ?: rq_i->curr;

- if (!rq->core->core_cookie)
- continue;
if (p == rq_i->idle && rq_i->nr_running) {
cpustat = kcpustat_cpu(i).cpustat;
- cpustat[CPUTIME_COOKIED_FORCEIDLE] += delta;
+ if (rq->core->core_cookie)
+ cpustat[CPUTIME_COOKIED_FORCEIDLE] += delta;
+ else
+ cpustat[CPUTIME_UNCOOKIED_FORCEIDLE] += delta;
}
}

--
1.8.3.1
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