From: Rik van Riel <[email protected]> The CONFIG_VIRT_CPU_ACCOUNTING_GEN irq time tracking code does not appear to currently work right.
On CPUs that are nohz_full, people typically do not assign IRQs. On the housekeeping CPU (when a system is booted up with nohz_full), sampling should work ok to determine irq and softirq time use, but that only covers the housekeeping CPU itself, not the other non-nohz_full CPUs. On CPUs that are nohz_idle (the typical way a distro kernel is booted), irq time is not accounted at all while the CPU is idle, due to the lack of timer ticks. Remove the VTIME_GEN vtime irq time code. The next patch will allow NO_HZ_FULL kernels to use the IRQ_TIME_ACCOUNTING code. Signed-off-by: Rik van Riel <[email protected]> --- include/linux/vtime.h | 32 ++++++++++++++------------------ kernel/sched/cputime.c | 16 +++------------- 2 files changed, 17 insertions(+), 31 deletions(-) diff --git a/include/linux/vtime.h b/include/linux/vtime.h index fa2196990f84..d1977d84ebdf 100644 --- a/include/linux/vtime.h +++ b/include/linux/vtime.h @@ -14,6 +14,18 @@ struct task_struct; */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE static inline bool vtime_accounting_cpu_enabled(void) { return true; } + +#ifdef __ARCH_HAS_VTIME_ACCOUNT +extern void vtime_account_irq_enter(struct task_struct *tsk); +#else +extern void vtime_common_account_irq_enter(struct task_struct *tsk); +static inline void vtime_account_irq_enter(struct task_struct *tsk) +{ + if (vtime_accounting_cpu_enabled()) + vtime_common_account_irq_enter(tsk); +} +#endif /* __ARCH_HAS_VTIME_ACCOUNT */ + #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN @@ -64,17 +76,6 @@ 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); -#ifdef __ARCH_HAS_VTIME_ACCOUNT -extern void vtime_account_irq_enter(struct task_struct *tsk); -#else -extern void vtime_common_account_irq_enter(struct task_struct *tsk); -static inline void vtime_account_irq_enter(struct task_struct *tsk) -{ - if (vtime_accounting_cpu_enabled()) - vtime_common_account_irq_enter(tsk); -} -#endif /* __ARCH_HAS_VTIME_ACCOUNT */ - #else /* !CONFIG_VIRT_CPU_ACCOUNTING */ static inline void vtime_task_switch(struct task_struct *prev) { } @@ -85,13 +86,8 @@ static inline void vtime_account_irq_enter(struct task_struct *tsk) { } #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN extern void arch_vtime_task_switch(struct task_struct *tsk); -extern void vtime_gen_account_irq_exit(struct task_struct *tsk); - -static inline void vtime_account_irq_exit(struct task_struct *tsk) -{ - if (vtime_accounting_cpu_enabled()) - vtime_gen_account_irq_exit(tsk); -} +static inline void vtime_account_irq_enter(struct task_struct *tsk) { } +static inline void vtime_account_irq_exit(struct task_struct *tsk) { } extern void vtime_user_enter(struct task_struct *tsk); diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 15b813c014be..0280528800f2 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -720,14 +720,14 @@ 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_jiffies, steal_jiffies; + unsigned long delta_jiffies, other_jiffies; delta_jiffies = now - tsk->vtime_snap; - steal_jiffies = steal_account_process_tick(delta_jiffies); + other_jiffies = account_other_ticks(delta_jiffies); WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); tsk->vtime_snap = now; - return jiffies_to_cputime(delta_jiffies - steal_jiffies); + return jiffies_to_cputime(delta_jiffies - other_jiffies); } static void __vtime_account_system(struct task_struct *tsk) @@ -747,16 +747,6 @@ void vtime_account_system(struct task_struct *tsk) write_seqcount_end(&tsk->vtime_seqcount); } -void vtime_gen_account_irq_exit(struct task_struct *tsk) -{ - write_seqcount_begin(&tsk->vtime_seqcount); - if (vtime_delta(tsk)) - __vtime_account_system(tsk); - if (context_tracking_in_user()) - tsk->vtime_snap_whence = VTIME_USER; - write_seqcount_end(&tsk->vtime_seqcount); -} - void vtime_account_user(struct task_struct *tsk) { cputime_t delta_cpu; -- 2.5.5
