[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Scalable Event Channel ABI design (draft A)
On 05/02/2013 15:54, "David Vrabel" <david.vrabel@xxxxxxxxxx> wrote: > On 05/02/13 15:49, Keir Fraser wrote: >> On 05/02/2013 14:48, "David Vrabel" <david.vrabel@xxxxxxxxxx> wrote: >> >>>> 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. >>> >>> This design originally (before I posted it) did have per-VCPU event >>> arrays but I changed it to per-domain to reduce the memory footprint. >> >> Okay, I wonder how much it actually matters anyhow... >> >> Oh by the way you say the control block is 128 bytes and will easily fit in >> the existing struct vcpu_info. That existing structure is 64 bytes in total. >> So how does that work then? > > I meant struct vcpu_info can be extended without it growing to more than > a page. i.e., it fits into the guest page provided in the > VCPUOP_register_vcpu_info call so no additional pages need to be > globally mapped for the control block. Oh, I see so any guest that uses the new event-channel interface will understand that vcpu_info is extended to contain it. Well, that makes sense. It's not what your document says though. -- Keir > David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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