[mythtv-users] OT? /proc/pci

[Jason Kraftcheck]

Joel Anderson wrote:
> Marc-David Meijer wrote:
> 
> As I understand it, PCI devices don't depend on IRQs anyway.  They use
> interrupt "channels", and IRQs are just kept around to keep legacy stuff
> happy.  You will often see many devices appear to "share" the same IRQ,
> but it is not really true since IRQ's can't really _be_ shared.
> 
> Someone please comment if I haven't explained this correctly.  It's a
> simplification, but it basically means that IRQ issues shouldn't come
> into play unless you have some legacy hardware in the system also.

I'm no expert either, but I think they are actually "shared".  The
interrupt handler must poll each device by invoking the interrupt
handler in the driver for each device sharing the interrupt.  Thus
there's a slight performance loss when sharing interrupts, and also the
possibility for buggy drivers to interfere with each other.