lkml.org 
[lkml]   [2010]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [tip:irq/core] x86: Sanitize apb timer interrupt handling

Hi tglx,

You are right, i am already doing the enable/disable dance.

Thanks for pointing it out, patiently.

Jacob

Thomas Gleixner Wed, 13 Oct 2010 00:26:08 +0200 (CEST)
>On Tue, 12 Oct 2010, Jacob Pan wrote:
>
>> Thomas Gleixner Tue, 12 Oct 2010 23:28:19 +0200 (CEST)
>> >On Tue, 12 Oct 2010, Jacob Pan wrote:
>> >
>> >>
>> >> >x86: Sanitize apb timer interrupt handling
>> >> >
>> >> >Disable the interrupt in CPU_DEAD where it belongs.
>> >> My main concern is the performance cost. The power management code for
>> >> Moorestown system make use of the cpu hotplug code (disable_nonboot_cpus)
>> >> but much more frequently. The system low power states are call S0 idle
>> >> state (s0ix).
>> >>
>> >> Leaving the irq enabled at the chip and desc level between S0ix states
>> >> might give some performance benefit. That was my original thought.
>> >> Will it cause problems?
>> >
>> >Errm. I merily moved it to the place where it should be. You do the
>> >disable/enable dance already today.
>> >
>> I think I only do disable/enable at the timer HW level today during cpu hp
>> notification, not calling disable_irq(). Am i missing something?
>
>apbt_setup_irq()
>{
> ...
>
>---> disable_irq(adev->irq);
> desc->status |= IRQ_MOVE_PCNTXT;
> irq_set_affinity(adev->irq, cpumask_of(adev->cpu));
> /* APB timer irqs are set up as mp_irqs, timer is edge triggerred */
> set_irq_chip_and_handler_name(adev->irq, chip, handle_edge_irq, "edge");
>---> enable_irq(adev->irq);
> if (system_state == SYSTEM_BOOTING)
> ...
>}
>
>So that's a disable/enable pair on every cpu hotplug, right ?
>
>Now I moved the disable to CPU_DEAD where it belongs and the enable
>stayed at the same place.
>
>Thanks,
>
> tglx
yo


\
 
 \ /
  Last update: 2010-10-13 20:13    [W:0.033 / U:0.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site