lkml.org 
[lkml]   [2003]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: userspace irq balancer
William Lee Irwin III <wli@holomorphy.com> wrote:
>> In
>> the userspace implementation the reprogramming is done infrequently
>> enough to make even significant cost negligible; in-kernel the cost
>> is entirely uncontrolled and the rate of reprogramming unlimited.

On Mon, May 26, 2003 at 06:59:20PM -0700, Andrew Morton wrote:
> eh?
> #define MAX_BALANCED_IRQ_INTERVAL (5*HZ)
> #define MIN_BALANCED_IRQ_INTERVAL (HZ/2)

The number of interrupt sources on a system ends up scaling this up to
numerous IO-APIC RTE reprograms and ioapic_lock acquisitions per-second
(granted, with a 5s timeout between reprogramming storms) where it
competes against IO-APIC interrupt acknowledgements.

Making the lock per- IO-APIC would at least put a bound on the number
of competitors mutually interfering with each other, but a tighter
bound on the amount of work than NR_IRQS would be more useful than that.


-- wli
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:35    [from the cache]
©2003-2011 Jasper Spaans