Re: [Qemu-devel] plan for device assignment upstream

[Jan Kiszka]

On 2012-07-02 11:18, Michael S. Tsirkin wrote:
> I've been thinking hard about Jan's patches for device
> assignment. Basically while I thought it makes sense
> to make all devices: assignment and not - behave the
> same and use same APIs for injecting irqs, Anthony thinks there is huge
> value in making irq propagation hierarchical and device assignment
> should be special cased.

On the long term, we will need direct injection, ie. caching, to allow
making it lock-less. Stepping through all intermediate layers will cause
troubles, at least performance-wise, when having to take and drop a lock
at each stop.

> 
> We seem to be at impasse for now and I think merging
> assignment ASAP has higher value than this specific
> issue. So I fold - let's do it as Anthony and Jan's
> original patches proposed.
> 
> Jan, can you please rebase and repost your original patchset (against
> master, not against pci) that added query for host irqs callbacks for
> device assignment? I'll re-review ignoring the idea of using the cache,
> with intent apply after I'll drop cache code from the pci branch in a
> couple of days (busy otherwise now).

OK, will do ASAP.

> 
> I still intend to rework this later on, but that can wait.
> 
> Thanks,
> 

Thanks as well,
Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux