[PATCH] sched/cputime: add steal time support to full dynticks CPU time accounting

Wanpeng Li
2016-05-10T05:34:44Z

From: Wanpeng Li <wanpeng.li@hotmail.com>

This patch adds steal guest time support to full dynticks CPU time
accounting. After commit ff9a9b4c(sched, time: Switch VIRT_CPU_ACCOUNTING_GEN
to jiffy granularity), time is jiffy based sampling even if it's
still listened to ring boundaries, so steal_account_process_tick()
is reused to account how much 'ticks' are steal time after the
last accumulation.

Suggested-by: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
kernel/sched/cputime.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..b96bd8f 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -257,7 +257,7 @@ void account_idle_time(cputime_t cputime)
cpustat[CPUTIME_IDLE] += (__force u64) cputime;
}

-static __always_inline bool steal_account_process_tick(void)
+static __always_inline unsigned long steal_account_process_tick(void)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(&paravirt_steal_enabled)) {
@@ -279,7 +279,7 @@ static __always_inline bool steal_account_process_tick(void)
return steal_jiffies;
}
#endif
- return false;
+ return 0;
}

/*
@@ -691,8 +691,11 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)

static void __vtime_account_system(struct task_struct *tsk)
{
+ unsigned long steal_time = steal_account_process_tick();
cputime_t delta_cpu = get_vtime_delta(tsk);

+ delta_cpu = steal_time ? (delta_cpu -
+ jiffies_to_cputime(steal_time)) : delta_cpu;
account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
}

@@ -723,7 +726,11 @@ void vtime_account_user(struct task_struct *tsk)
write_seqcount_begin(&tsk->vtime_seqcount);
tsk->vtime_snap_whence = VTIME_SYS;
if (vtime_delta(tsk)) {
+ unsigned long steal_time = steal_account_process_tick();
delta_cpu = get_vtime_delta(tsk);
+
+ delta_cpu = steal_time ? (delta_cpu -
+ jiffies_to_cputime(steal_time)) : delta_cpu;
account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
}
write_seqcount_end(&tsk->vtime_seqcount);
--
1.9.1