Messages in this thread | | | Date | Thu, 12 Jun 2008 17:55:33 -0700 | From | Andrew Morton <> | Subject | Re: [patch 6/6] x86: add c1e aware idle function |
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On Thu, 12 Jun 2008 10:29:00 -0000 Thomas Gleixner <tglx@linutronix.de> wrote:
> +static void c1e_idle(void) > +{ > + static cpumask_t c1e_mask = CPU_MASK_NONE; > + static int c1e_detected; > + > + if (need_resched()) > + return; > + > + if (!c1e_detected) { > + u32 lo, hi; > + > + rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); > + if (lo & K8_INTP_C1E_ACTIVE_MASK) { > + c1e_detected = 1; > + mark_tsc_unstable("TSC halt in C1E"); > + printk(KERN_INFO "System has C1E enabled\n"); > + } > + } > + > + if (c1e_detected) { > + int cpu = smp_processor_id(); > + > + if (!cpu_isset(cpu, c1e_mask)) { > + cpu_set(cpu, c1e_mask); > + /* Force broadcast so ACPI can not interfere */ > + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE, > + &cpu); > + printk(KERN_INFO "Switch to broadcast mode on CPU%d\n", > + cpu); > + } > + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); > + default_idle(); > + local_irq_disable(); > + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); > + local_irq_enable();
I worked it out! It took me a while.
This function is called with local irqs disabled.
default_idle() is entered with local irqs disabled but returns with them enabled.
clockevents_notify() is supposed to be called with local irqs disabled.
This functions returns with local irqs enabled.
Was I right? None of any of that is documented anywhere. But it should be.
> + } else > + default_idle(); > +}
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