From b58c35840521bb02b150e1d0d34ca9197f8b7145 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Wed, 13 Jul 2016 16:50:02 +0200 Subject: [PATCH] sched/cputime: Replace VTIME_GEN irq time code with IRQ_TIME_ACCOUNTING code The CONFIG_VIRT_CPU_ACCOUNTING_GEN irq time tracking code does not appear to currently work right. On CPUs without nohz_full=, only tick based irq time sampling is done, which breaks down when dealing with a nohz_idle CPU. On firewalls and similar systems, no ticks may happen on a CPU for a while, and the irq time spent may never get accounted properly. This can cause issues with capacity planning and power saving, which use the CPU statistics as inputs in decision making. Remove the VTIME_GEN vtime irq time code, and replace it with the IRQ_TIME_ACCOUNTING code, when selected as a config option by the user. Signed-off-by: Rik van Riel Signed-off-by: Frederic Weisbecker Cc: Linus Torvalds Cc: Mike Galbraith Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Radim Krcmar Cc: Thomas Gleixner Cc: Wanpeng Li Link: http://lkml.kernel.org/r/1468421405-20056-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- include/linux/vtime.h | 32 ++++++++++++++------------------ init/Kconfig | 6 +++--- kernel/sched/cputime.c | 16 +++------------- 3 files changed, 20 insertions(+), 34 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/init/Kconfig b/init/Kconfig index c02d89777713..787dd76acf29 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -375,9 +375,11 @@ config VIRT_CPU_ACCOUNTING_GEN If unsure, say N. +endchoice + config IRQ_TIME_ACCOUNTING bool "Fine granularity task level IRQ time accounting" - depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL + depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE help Select this option to enable fine granularity task irq time accounting. This is done by reading a timestamp on each @@ -386,8 +388,6 @@ config IRQ_TIME_ACCOUNTING If in doubt, say N here. -endchoice - config BSD_PROCESS_ACCT bool "BSD Process Accounting" depends on MULTIUSER diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index db82ae12cf01..ca7e33cb0967 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -711,14 +711,14 @@ 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); - cputime_t delta, steal; + cputime_t delta, other; delta = jiffies_to_cputime(now - tsk->vtime_snap); - steal = steal_account_process_time(delta); + other = account_other_time(delta); WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); tsk->vtime_snap = now; - return delta - steal; + return delta - other; } static void __vtime_account_system(struct task_struct *tsk) @@ -738,16 +738,6 @@ 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; -- 2.20.1