On 13/06/2016 12:32, Wanpeng Li wrote:
> 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)
>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
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