From 6a61671bb2f3a1bd12cd17b8fca811a624782632 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sun, 16 Dec 2012 20:00:34 +0100 Subject: cputime: Safely read cputime of full dynticks CPUs While remotely reading the cputime of a task running in a full dynticks CPU, the values stored in utime/stime fields of struct task_struct may be stale. Its values may be those of the last kernel <-> user transition time snapshot and we need to add the tickless time spent since this snapshot. To fix this, flush the cputime of the dynticks CPUs on kernel <-> user transition and record the time / context where we did this. Then on top of this snapshot and the current time, perform the fixup on the reader side from task_times() accessors. Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Ingo Molnar Cc: Li Zhong Cc: Namhyung Kim Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner [fixed kvm module related build errors] Signed-off-by: Sedat Dilek --- include/linux/hardirq.h | 4 ++-- include/linux/init_task.h | 11 +++++++++++ include/linux/kvm_host.h | 20 ++++++++++++++++++-- include/linux/sched.h | 27 ++++++++++++++++++++++----- include/linux/vtime.h | 47 +++++++++++++++++++++++------------------------ 5 files changed, 76 insertions(+), 33 deletions(-) (limited to 'include') diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 624ef3f45c8e..7105d5cbb762 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -153,7 +153,7 @@ extern void rcu_nmi_exit(void); */ #define __irq_enter() \ do { \ - vtime_account_irq_enter(current); \ + account_irq_enter_time(current); \ add_preempt_count(HARDIRQ_OFFSET); \ trace_hardirq_enter(); \ } while (0) @@ -169,7 +169,7 @@ extern void irq_enter(void); #define __irq_exit() \ do { \ trace_hardirq_exit(); \ - vtime_account_irq_exit(current); \ + account_irq_exit_time(current); \ sub_preempt_count(HARDIRQ_OFFSET); \ } while (0) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 6d087c5f57f7..cc898b871cef 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -10,6 +10,7 @@ #include #include #include +#include #include #ifdef CONFIG_SMP @@ -141,6 +142,15 @@ extern struct task_group root_task_group; # define INIT_PERF_EVENTS(tsk) #endif +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN +# define INIT_VTIME(tsk) \ + .vtime_seqlock = __SEQLOCK_UNLOCKED(tsk.vtime_seqlock), \ + .vtime_snap = 0, \ + .vtime_snap_whence = VTIME_SYS, +#else +# define INIT_VTIME(tsk) +#endif + #define INIT_TASK_COMM "swapper" /* @@ -210,6 +220,7 @@ extern struct task_group root_task_group; INIT_TRACE_RECURSION \ INIT_TASK_RCU_PREEMPT(tsk) \ INIT_CPUSET_SEQ \ + INIT_VTIME(tsk) \ } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4fe2396401da..b7996a768eb2 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -741,7 +741,7 @@ static inline int kvm_deassign_device(struct kvm *kvm, } #endif /* CONFIG_IOMMU_API */ -static inline void guest_enter(void) +static inline void __guest_enter(void) { /* * This is running in ioctl context so we can avoid @@ -751,7 +751,7 @@ static inline void guest_enter(void) current->flags |= PF_VCPU; } -static inline void guest_exit(void) +static inline void __guest_exit(void) { /* * This is running in ioctl context so we can avoid @@ -761,6 +761,22 @@ static inline void guest_exit(void) current->flags &= ~PF_VCPU; } +#ifdef CONFIG_CONTEXT_TRACKING +extern void guest_enter(void); +extern void guest_exit(void); + +#else /* !CONFIG_CONTEXT_TRACKING */ +static inline void guest_enter(void) +{ + __guest_enter(); +} + +static inline void guest_exit(void) +{ + __guest_exit(); +} +#endif /* !CONFIG_CONTEXT_TRACKING */ + static inline void kvm_guest_enter(void) { unsigned long flags; diff --git a/include/linux/sched.h b/include/linux/sched.h index a9c608b6154e..a9fa5145e1a7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1367,6 +1367,15 @@ struct task_struct { cputime_t gtime; #ifndef CONFIG_VIRT_CPU_ACCOUNTING struct cputime prev_cputime; +#endif +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN + seqlock_t vtime_seqlock; + unsigned long long vtime_snap; + enum { + VTIME_SLEEPING = 0, + VTIME_USER, + VTIME_SYS, + } vtime_snap_whence; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ @@ -1792,11 +1801,13 @@ static inline void put_task_struct(struct task_struct *t) __put_task_struct(t); } -static inline cputime_t task_gtime(struct task_struct *t) -{ - return t->gtime; -} - +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN +extern void task_cputime(struct task_struct *t, + cputime_t *utime, cputime_t *stime); +extern void task_cputime_scaled(struct task_struct *t, + cputime_t *utimescaled, cputime_t *stimescaled); +extern cputime_t task_gtime(struct task_struct *t); +#else static inline void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) { @@ -1815,6 +1826,12 @@ static inline void task_cputime_scaled(struct task_struct *t, if (stimescaled) *stimescaled = t->stimescaled; } + +static inline cputime_t task_gtime(struct task_struct *t) +{ + return t->gtime; +} +#endif extern void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st); extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st); diff --git a/include/linux/vtime.h b/include/linux/vtime.h index bb50c3ca0d79..71a5782d8c59 100644 --- a/include/linux/vtime.h +++ b/include/linux/vtime.h @@ -8,35 +8,44 @@ extern void vtime_task_switch(struct task_struct *prev); extern void vtime_account_system(struct task_struct *tsk); extern void vtime_account_idle(struct task_struct *tsk); extern void vtime_account_user(struct task_struct *tsk); -extern void vtime_account(struct task_struct *tsk); +extern void vtime_account_irq_enter(struct task_struct *tsk); -#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN -extern bool vtime_accounting_enabled(void); -#else +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE static inline bool vtime_accounting_enabled(void) { return true; } #endif #else /* !CONFIG_VIRT_CPU_ACCOUNTING */ + static inline void vtime_task_switch(struct task_struct *prev) { } static inline void vtime_account_system(struct task_struct *tsk) { } static inline void vtime_account_user(struct task_struct *tsk) { } -static inline void vtime_account(struct task_struct *tsk) { } +static inline void vtime_account_irq_enter(struct task_struct *tsk) { } static inline bool vtime_accounting_enabled(void) { return false; } #endif #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN -static inline void arch_vtime_task_switch(struct task_struct *tsk) { } -static inline void vtime_user_enter(struct task_struct *tsk) -{ - vtime_account_system(tsk); -} +extern void arch_vtime_task_switch(struct task_struct *tsk); +extern void vtime_account_irq_exit(struct task_struct *tsk); +extern bool vtime_accounting_enabled(void); +extern void vtime_user_enter(struct task_struct *tsk); static inline void vtime_user_exit(struct task_struct *tsk) { vtime_account_user(tsk); } +extern void vtime_guest_enter(struct task_struct *tsk); +extern void vtime_guest_exit(struct task_struct *tsk); +extern void vtime_init_idle(struct task_struct *tsk); #else +static inline void vtime_account_irq_exit(struct task_struct *tsk) +{ + /* On hard|softirq exit we always account to hard|softirq cputime */ + vtime_account_system(tsk); +} static inline void vtime_user_enter(struct task_struct *tsk) { } static inline void vtime_user_exit(struct task_struct *tsk) { } +static inline void vtime_guest_enter(struct task_struct *tsk) { } +static inline void vtime_guest_exit(struct task_struct *tsk) { } +static inline void vtime_init_idle(struct task_struct *tsk) { } #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING @@ -45,25 +54,15 @@ extern void irqtime_account_irq(struct task_struct *tsk); static inline void irqtime_account_irq(struct task_struct *tsk) { } #endif -static inline void vtime_account_irq_enter(struct task_struct *tsk) +static inline void account_irq_enter_time(struct task_struct *tsk) { - /* - * Hardirq can interrupt idle task anytime. So we need vtime_account() - * that performs the idle check in CONFIG_VIRT_CPU_ACCOUNTING. - * Softirq can also interrupt idle task directly if it calls - * local_bh_enable(). Such case probably don't exist but we never know. - * Ksoftirqd is not concerned because idle time is flushed on context - * switch. Softirqs in the end of hardirqs are also not a problem because - * the idle time is flushed on hardirq time already. - */ - vtime_account(tsk); + vtime_account_irq_enter(tsk); irqtime_account_irq(tsk); } -static inline void vtime_account_irq_exit(struct task_struct *tsk) +static inline void account_irq_exit_time(struct task_struct *tsk) { - /* On hard|softirq exit we always account to hard|softirq cputime */ - vtime_account_system(tsk); + vtime_account_irq_exit(tsk); irqtime_account_irq(tsk); } -- cgit v1.2.3