From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
This patch adds guest steal-time support to full dynticks CPU
time accounting. After the following commit:
ff9a9b4c4334 ("sched, time: Switch VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")
... time sampling became jiffy based, even if it's still listened
to ring boundaries, so steal_account_process_tick() is reused
to account how many 'ticks' are stolen-time, after the last accumulation.
Suggested-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
---
v4 -> v5:
* apply same logic to account_idle_time, so change get_vtime_delta instead
v3 -> v4:
* fix grammar errors, thanks Ingo
* cleanup fragile codes, thanks Ingo
v2 -> v3:
* convert steal time jiffies to cputime
v1 -> v2:
* fix divide zero bug, thanks Rik
kernel/sched/cputime.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..b62f9f8 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(¶virt_steal_enabled)) {
@@ -279,7 +279,7 @@ static __always_inline bool steal_account_process_tick(void)
return steal_jiffies;
}
#endif
- return false;
+ return 0;
}
/*
@@ -681,12 +681,17 @@ static cputime_t vtime_delta(struct task_struct *tsk)
static cputime_t get_vtime_delta(struct task_struct *tsk)
{
unsigned long now = READ_ONCE(jiffies);
- unsigned long delta = now - tsk->vtime_snap;
+ cputime_t delta_time, steal_time;
+ steal_time = jiffies_to_cputime(steal_account_process_tick());
+ delta_time = jiffies_to_cputime(now - tsk->vtime_snap);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
tsk->vtime_snap = now;
- return jiffies_to_cputime(delta);
+ if (steal_time < delta_time)
+ delta_time -= steal_time;
+
+ return delta_time;
}
static void __vtime_account_system(struct task_struct *tsk)
--
1.9.1
--
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