Re: [Xen-devel] Scalable Event Channel ABI design (draft A)

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.02.13 at 20:59, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 04/02/2013 17:52, "David Vrabel" <david.vrabel@xxxxxxxxxx> wrote:
>> Here is a design for a scalable event channel ABI for Xen.  It has a
>> number of benefits over the design currently being proposed by Wei Lui.
>> 
>> * More event channels (>100,000).
>> * 16 event priorities.
>> * Reduced memory requirements (only 1 additional page per domU).
>> * The use of FIFOs for events ensures fairness, whereas it is difficult
>> to reason about the fairness with the current bitmap system.
> 
> I have some sympathy for this design. It's primary downside compared with
> the 3-level alternative is its greater space cost (32*#vcpus). However, as
> you say the fairness and prioritisation features are rather nice. Also
> having the data structures be per vcpu may well help avoid cacheline
> contention on busy multi-vcpu guests.
> 
> Interested in what others think, but I may actually prefer a ground-up
> redesign like this.

So do I, fwiw.

Jan


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