Re: Interrupt forwarding

[Jon Smirl <jonsmirl@gmail.com>]

On Sat, 12 Mar 2005 19:59:15 -0000, Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> wrote:
> 
> 
> > > We don't go that far. A sensible approach would be to require the
> > > driver to be restarted, and to reset the hardware device, before
> > > unmasking. Or to rate limit each interrupt line to an
> > > administrator-configurable 'reasonable' number of IRQs per second --
> > > this might also catch bugs where drivers are not properly acking
> > > devices for other reasons.
> >
> > In x86 boxes almost everything is shared. Leaving the interrupt masked
> > off will probably disable 20% of the hardware in the box.
> 
> That's not my experience, certainly on modern server hardware. On
> systems with an IOAPIC its rare to see a shared interrupt, and even if
> you do you can typically avoid it just by swapping a couple of PCI cards
> around.
> 
> Ian
> 

If I load video drivers two more drivers will share interrupts. 169
with have 4 devices on it instead of three.

[jonsmirl@jonsmirl proc]$ cat interrupts
           CPU0       CPU1
  0:     484259     448188    IO-APIC-edge  timer
  8:          0          0    IO-APIC-edge  rtc
  9:          0          0   IO-APIC-level  acpi
 14:        776        762    IO-APIC-edge  ide0
 15:       8040       7726    IO-APIC-edge  ide1
169:      37509          0   IO-APIC-level  libata, uhci_hcd:usb4, eth0
185:          5          0   IO-APIC-level  ehci_hcd:usb1
193:        548        272   IO-APIC-level  uhci_hcd:usb2, uhci_hcd:usb5
201:          0          0   IO-APIC-level  uhci_hcd:usb3
209:          3          0   IO-APIC-level  ohci1394
NMI:          0          0
LOC:     932357     932306
ERR:          0
MIS:          0
[jonsmirl@jonsmirl proc]$

-- 
Jon Smirl
jonsmirl@gmail.com


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