Re: Why no interrupt priorities?

["Randy.Dunlap" <rddunlap@osdl.org>]

On Thu, 26 Feb 2004 17:36:34 -0800 "Grover, Andrew" <andrew.grover@intel.com> wrote:

| > On Thursday 26 February 2004 13:30, Arjan van de Ven wrote:
| > > hardware IRQ priorities are useless for the linux model. In 
| > linux, the
| > > hardirq runs *very* briefly and then lets the softirq context do the
| > > longer taking work. hardware irq priorities then don't matter really
| > > because the hardirq's are hardly ever interrupted really, 
| > and when they
| > > are they cause a performance *loss* due to cache trashing. 
| > The latency
| > > added by waiting briefly is going to be really really short 
| > for any sane
| > > hardware.
| 
| Is the assumption that hardirq handlers are superfast also the reason
| why Linux calls all handlers on a shared interrupt, even if the first
| handler reports it was for its device?

Somehow I don't think that's the reasoning.

Is there a safe method to determine that there are no other pending
interrupts on one shared interrupt?  i.e., that other devices don't
also have interrupts pending?

--
~Randy