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 listening to ring
boundaries, so steal_account_process_tick() is reused to account how many
'ticks' are stolen-time, after the last accumulation.
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>
---
kernel/sched/cputime.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..3d60e5d 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(unsigned long max_jiffies)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(¶virt_steal_enabled)) {
@@ -272,14 +272,14 @@ static __always_inline bool steal_account_process_tick(void)
* time in jiffies. Lets cast the result to jiffies
* granularity and account the rest on the next rounds.
*/
- steal_jiffies = nsecs_to_jiffies(steal);
+ steal_jiffies = min(nsecs_to_jiffies(steal), max_jiffies);
this_rq()->prev_steal_time += jiffies_to_nsecs(steal_jiffies);
account_steal_time(jiffies_to_cputime(steal_jiffies));
return steal_jiffies;
}
#endif
- return false;
+ return 0;
}
/*
@@ -346,7 +346,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
u64 cputime = (__force u64) cputime_one_jiffy;
u64 *cpustat = kcpustat_this_cpu->cpustat;
- if (steal_account_process_tick())
+ if (steal_account_process_tick(ULONG_MAX))
return;
cputime *= ticks;
@@ -477,7 +477,7 @@ void account_process_tick(struct task_struct *p, int user_tick)
return;
}
- if (steal_account_process_tick())
+ if (steal_account_process_tick(ULONG_MAX))
return;
if (user_tick)
@@ -681,12 +681,14 @@ 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;
+ unsigned long delta_jiffies, steal_jiffies;
+ delta_jiffies = now - tsk->vtime_snap;
+ steal_jiffies = steal_account_process_tick(delta_jiffies);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
tsk->vtime_snap = now;
- return jiffies_to_cputime(delta);
+ return jiffies_to_cputime(delta_jiffies - steal_jiffies);
}
static void __vtime_account_system(struct task_struct *tsk)
--
1.9.1
--
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