提交 d267f87f 编写于 作者: V Venkatesh Pallipadi 提交者: Ingo Molnar

sched: Call tick_check_idle before __irq_enter

When CPU is idle and on first interrupt, irq_enter calls tick_check_idle()
to notify interruption from idle. But, there is a problem if this call
is done after __irq_enter, as all routines in __irq_enter may find
stale time due to yet to be done tick_check_idle.

Specifically, trace calls in __irq_enter when they use global clock and also
account_system_vtime change in this patch as it wants to use sched_clock_cpu()
to do proper irq timing.

But, tick_check_idle was moved after __irq_enter intentionally to
prevent problem of unneeded ksoftirqd wakeups by the commit ee5f80a9:

    irq: call __irq_enter() before calling the tick_idle_check
    Impact: avoid spurious ksoftirqd wakeups

Moving tick_check_idle() before __irq_enter and wrapping it with
local_bh_enable/disable would solve both the problems.
Fixed-by: NYong Zhang <yong.zhang0@gmail.com>
Signed-off-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-9-git-send-email-venki@google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
上级 aa483808
......@@ -1974,8 +1974,8 @@ void account_system_vtime(struct task_struct *curr)
local_irq_save(flags);
now = sched_clock();
cpu = smp_processor_id();
now = sched_clock_cpu(cpu);
delta = now - per_cpu(irq_start_time, cpu);
per_cpu(irq_start_time, cpu) = now;
/*
......
......@@ -296,10 +296,16 @@ void irq_enter(void)
rcu_irq_enter();
if (idle_cpu(cpu) && !in_interrupt()) {
__irq_enter();
/*
* Prevent raise_softirq from needlessly waking up ksoftirqd
* here, as softirq will be serviced on return from interrupt.
*/
local_bh_disable();
tick_check_idle(cpu);
} else
__irq_enter();
_local_bh_enable();
}
__irq_enter();
}
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册