Re: why no IO-APIC?

[Warren Togami <warren@xxxxxxxxxx>]

Florin Andrei wrote:
> What is the reason why IO-APIC is disabled in the RH kernels?
>
> I have a desktop system, optimized for heavy multimedia work, which has
> quite a few PCI controllers in it (IEEE1394, analog video capture, etc.)
> besides the usual stuff (network, video). The normal IRQ space is quite
> tight. Here's a sample of /proc/interrupts:
>
> Due to IRQ overlaps, the performance of the system is quite suboptimal,
> especially when devices using the same IRQ are working at the same time.
>
> Enabling IO-APIC makes room above IRQ 15, potentially eliminating those
> nasty interrupt overlaps. I've noticed that when using a vanilla 2.4.20
> kernel with IO-APIC enabled.
>
> The system has an AthlonXP proc, and an nForce1 motherboard.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=62295

I'm not sure if this is related, but "local apic" seems to cause 
problems for just about every mobile Athlon as well as several other 
Athlon machines.

When I enable APIC on 2.4.x and 2.5.x kernels on these machines it 
causes this kind of behavior, or sometimes worse (kernel panics).

Warren Togami
warren@togaim.com



--
Phoebe-list mailing list
Phoebe-list@redhat.com
https://listman.redhat.com/mailman/listinfo/phoebe-list