Re: Q: x86 interrupt arrival after cli

[Ion Badulescu <ionut@cs.columbia.edu>]

On Wed, 15 May 2002 20:27:20 -0400, Bart Trojanowski <bart@jukie.net> wrote:
> [-- text/plain, encoding quoted-printable, 14 lines --]
> 
> Quick question for the x86 gurus:
> 
> If a hardware interrupt arrives within a spin_lock_irqsave &
> spin_unlock_irqrestore will the interrupt handler associated with said
> interrupt be called immediately after the spinlock is released?  
> 
> I am interested in any delays, even those less then a jiffie.

The interrupt will occur when the instruction after the "sti" finishes.
That's a one assembler instruction delay, i.e. a few clock cycles.

*Which* interrupt will be serviced first, however, depends on how 
many interrupt sources you have active and on the IRQ prioritization.

Ion

-- 
  It is better to keep your mouth shut and be thought a fool,
            than to open it and remove all doubt.