On 13/06/2016 12:32, Wanpeng Li wrote: > From: Wanpeng Li <[email protected]> > > 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 <[email protected]> > Cc: Peter Zijlstra (Intel) <[email protected]> > Cc: Rik van Riel <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Frederic Weisbecker <[email protected]> > Cc: Paolo Bonzini <[email protected]> > Cc: Radim Krčmář <[email protected]> > Signed-off-by: Wanpeng Li <[email protected]> > --- > 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 <[email protected]>
