Re: [Xen-devel] xen 4 only seeing one keyboard and mouse

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 24/08/2010 18:10, "Konrad Rzeszutek Wilk" <konrad.wilk@xxxxxxxxxx> wrote:

>> though the mouse and keyboard still don't work.
> 
> I spoke with Keir a bit and he mentioned that there was a major
> rework of the IRQs in 4.0, wherein we would store the IRQs per CPU
> structure. That is instead of having a "globally" accessible irq structure
> wherein CPUs might contend for it.

Specifically the feature is "per-CPU IDTs". This increases the system-wide
IRQ limit from ~200 to ~200*nr_cpus. However, there is an increase in
complexity in that the interrupt vector assigned to an IRQ is CPU-local, and
must be re-allocated when an IRQ's target is moved between CPUs.

The main patch is c/s 20073 by Xiantao Zhang. It is the single biggest IRQ
restructuring patch in Xen 4.0 campared with 3.4.

 -- Keir

> The folks at Intel did this so they might
> have a better idea - and I can dig up from the hg annotate logs who they
> are and we can ask them. But before we go that route, the other idea was
> try to disable the irq balance code. Try passing in 'noirqbalance' and see
> what happens



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