On Wed, Mar 08, 2000 at 06:44:51PM -0800, Linus Torvalds wrote:
>
>
> On Wed, 8 Mar 2000 yodaiken@fsmlabs.com wrote:
> > On a UP -- no change except code is more complex
> > On a SMP box performance loss without using affinity.
> > Take two spinlocks instead of one, more cache boucing etc.
>
> You've said that now several times, and you always ignore the answer that
> you are always given: normally you don't need any other spinlock if your
> interrupt controller can do the operations atomically. Which they actually
> usually can, at least the better ones.
>
> Ignoring that answer only makes you look silly. Don't do it.
The way you are getting an atomic operation on the level irqs is by
splitting it into two parts: unless I'm mistaken about it.
So the performance loss comes from the io-apic being frozen
until the interrupt handler returns and does a desc-end
You avoid the second spin lock by freezing the io-apic
Is that false?
-- --------------------------------------------------------- Victor Yodaiken FSMLabs: www.fsmlabs.com www.rtlinux.com FSMLabs is a servicemark and a service of VJY Associates L.L.C, New Mexico.- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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