Re: [Xen-devel] Design and Question: Eliminate Xen (RTDS) scheduler overhead on dedicated CPU

[Meng Xu <xumengpanda@xxxxxxxxx>]

2015-03-25 7:58 GMT-04:00 George Dunlap <george.dunlap@xxxxxxxxxxxxx>:

On 03/25/2015 01:48 AM, Meng Xu wrote:
> âExactly! I will do some measurement on the overhead in #2 before I really
> try to do it. Since #1 is fairly easy, I will first implement #1 and see
> how much gap it remains to achieve the bare-metal performance.

Interface-wise: I'm wondering if at the Xen or libxl level we really
need to have a whole new set of hypercalls, at least to implement #1.
Would it make sense for certain schedulers to automatically switch to
"no accounting" mode when the hard_affinity of a vcpu is limited to one
vcpu, and no other vcpus are also limited to that one vcpu?

âI guess you mean:â

certain schedulers to automatically switch to

"no accounting" mode when the hard_affinity of a vcpu is limited to one

â"â

cpu

â" (not vcpu)â

, and

ââ

no other vcpus are also limited to that one

â"â

cpu

â"â

?

âAm I correct? :-)â

âIf so, I think yes, it should be better than having a new hypercall because in this case, user does want to isolate a dedicated cpu to a dedicated vcpu. â

Best regards,

âMengâ

-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania

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