The following commit has been merged into the irq/core branch of tip: Commit-ID: d3759e7184f8f6187e62f8c4e7dcb1f6c47c075a Gitweb: https://git.kernel.org/tip/d3759e7184f8f6187e62f8c4e7dcb1f6c47c075a Author: Frederic Weisbecker <frederic@xxxxxxxxxx> AuthorDate: Wed, 02 Dec 2020 12:57:31 +01:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Wed, 02 Dec 2020 20:20:05 +01:00 irqtime: Move irqtime entry accounting after irq offset incrementation IRQ time entry is currently accounted before HARDIRQ_OFFSET or SOFTIRQ_OFFSET are incremented. This is convenient to decide to which index the cputime to account is dispatched. Unfortunately it prevents tick_irq_enter() from being called under HARDIRQ_OFFSET because tick_irq_enter() has to be called before the IRQ entry accounting due to the necessary clock catch up. As a result we don't benefit from appropriate lockdep coverage on tick_irq_enter(). To prepare for fixing this, move the IRQ entry cputime accounting after the preempt offset is incremented. This requires the cputime dispatch code to handle the extra offset. Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20201202115732.27827-5-frederic@xxxxxxxxxx --- include/linux/hardirq.h | 4 ++-- include/linux/vtime.h | 34 ++++++++++++++++++++++++---------- kernel/sched/cputime.c | 18 +++++++++++------- kernel/softirq.c | 6 +++--- 4 files changed, 40 insertions(+), 22 deletions(-) diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 754f67a..7c9d6a2 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -32,9 +32,9 @@ static __always_inline void rcu_irq_enter_check_tick(void) */ #define __irq_enter() \ do { \ - account_irq_enter_time(current); \ preempt_count_add(HARDIRQ_OFFSET); \ lockdep_hardirq_enter(); \ + account_hardirq_enter(current); \ } while (0) /* @@ -62,8 +62,8 @@ void irq_enter_rcu(void); */ #define __irq_exit() \ do { \ + account_hardirq_exit(current); \ lockdep_hardirq_exit(); \ - account_irq_exit_time(current); \ preempt_count_sub(HARDIRQ_OFFSET); \ } while (0) diff --git a/include/linux/vtime.h b/include/linux/vtime.h index 6c98674..041d652 100644 --- a/include/linux/vtime.h +++ b/include/linux/vtime.h @@ -83,32 +83,46 @@ static inline void vtime_init_idle(struct task_struct *tsk, int cpu) { } #endif #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE -extern void vtime_account_irq(struct task_struct *tsk); +extern void vtime_account_irq(struct task_struct *tsk, unsigned int offset); extern void vtime_account_softirq(struct task_struct *tsk); extern void vtime_account_hardirq(struct task_struct *tsk); extern void vtime_flush(struct task_struct *tsk); #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ -static inline void vtime_account_irq(struct task_struct *tsk) { } +static inline void vtime_account_irq(struct task_struct *tsk, unsigned int offset) { } +static inline void vtime_account_softirq(struct task_struct *tsk) { } +static inline void vtime_account_hardirq(struct task_struct *tsk) { } static inline void vtime_flush(struct task_struct *tsk) { } #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING -extern void irqtime_account_irq(struct task_struct *tsk); +extern void irqtime_account_irq(struct task_struct *tsk, unsigned int offset); #else -static inline void irqtime_account_irq(struct task_struct *tsk) { } +static inline void irqtime_account_irq(struct task_struct *tsk, unsigned int offset) { } #endif -static inline void account_irq_enter_time(struct task_struct *tsk) +static inline void account_softirq_enter(struct task_struct *tsk) { - vtime_account_irq(tsk); - irqtime_account_irq(tsk); + vtime_account_irq(tsk, SOFTIRQ_OFFSET); + irqtime_account_irq(tsk, SOFTIRQ_OFFSET); } -static inline void account_irq_exit_time(struct task_struct *tsk) +static inline void account_softirq_exit(struct task_struct *tsk) { - vtime_account_irq(tsk); - irqtime_account_irq(tsk); + vtime_account_softirq(tsk); + irqtime_account_irq(tsk, 0); +} + +static inline void account_hardirq_enter(struct task_struct *tsk) +{ + vtime_account_irq(tsk, HARDIRQ_OFFSET); + irqtime_account_irq(tsk, HARDIRQ_OFFSET); +} + +static inline void account_hardirq_exit(struct task_struct *tsk) +{ + vtime_account_hardirq(tsk); + irqtime_account_irq(tsk, 0); } #endif /* _LINUX_KERNEL_VTIME_H */ diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 02163d4..5f61165 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -44,12 +44,13 @@ static void irqtime_account_delta(struct irqtime *irqtime, u64 delta, } /* - * Called before incrementing preempt_count on {soft,}irq_enter + * Called after incrementing preempt_count on {soft,}irq_enter * and before decrementing preempt_count on {soft,}irq_exit. */ -void irqtime_account_irq(struct task_struct *curr) +void irqtime_account_irq(struct task_struct *curr, unsigned int offset) { struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime); + unsigned int pc; s64 delta; int cpu; @@ -59,6 +60,7 @@ void irqtime_account_irq(struct task_struct *curr) cpu = smp_processor_id(); delta = sched_clock_cpu(cpu) - irqtime->irq_start_time; irqtime->irq_start_time += delta; + pc = preempt_count() - offset; /* * We do not account for softirq time from ksoftirqd here. @@ -66,9 +68,9 @@ void irqtime_account_irq(struct task_struct *curr) * in that case, so as not to confuse scheduler with a special task * that do not consume any time, but still wants to run. */ - if (hardirq_count()) + if (pc & HARDIRQ_MASK) irqtime_account_delta(irqtime, delta, CPUTIME_IRQ); - else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) + else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd()) irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ); } @@ -417,11 +419,13 @@ void vtime_task_switch(struct task_struct *prev) } # endif -void vtime_account_irq(struct task_struct *tsk) +void vtime_account_irq(struct task_struct *tsk, unsigned int offset) { - if (hardirq_count()) { + unsigned int pc = preempt_count() - offset; + + if (pc & HARDIRQ_OFFSET) { vtime_account_hardirq(tsk); - } else if (in_serving_softirq()) { + } else if (pc & SOFTIRQ_OFFSET) { vtime_account_softirq(tsk); } else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) && is_idle_task(tsk)) { diff --git a/kernel/softirq.c b/kernel/softirq.c index 617009c..b8f42b3 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -315,10 +315,10 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) current->flags &= ~PF_MEMALLOC; pending = local_softirq_pending(); - account_irq_enter_time(current); __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET); in_hardirq = lockdep_softirq_start(); + account_softirq_enter(current); restart: /* Reset the pending bitmask before enabling irqs */ @@ -365,8 +365,8 @@ restart: wakeup_softirqd(); } + account_softirq_exit(current); lockdep_softirq_end(in_hardirq); - account_irq_exit_time(current); __local_bh_enable(SOFTIRQ_OFFSET); WARN_ON_ONCE(in_interrupt()); current_restore_flags(old_flags, PF_MEMALLOC); @@ -418,7 +418,7 @@ static inline void __irq_exit_rcu(void) #else lockdep_assert_irqs_disabled(); #endif - account_irq_exit_time(current); + account_hardirq_exit(current); preempt_count_sub(HARDIRQ_OFFSET); if (!in_interrupt() && local_softirq_pending()) invoke_softirq();
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