[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH RESEND 05/12] xen: numa-sched: make space for per-vcpu node-affinity

On 06/11/13 14:26, Dario Faggioli wrote:
On mer, 2013-11-06 at 11:44 +0000, George Dunlap wrote:
On 06/11/13 10:00, Dario Faggioli wrote:
I see, and that sounds sensible to me... It's mostly a matter a matter
of deciding whether o not we want something like that, and, if yes,
whether we want it based on hard of soft.

Personally, I think I agree with you on having it based on hard
affinities by default.

Let's see if George get to say something before I get to that part of
the (re)implementation. :-)
I would probably have it based on soft affinities, since that's where we
expect to have the domain's vcpus actually running most if the time;

True. However, doing that would rule out cpupool and vcpu-pinning.

I guess I was assuming that a vcpu's soft affinity would always be considered a subset of its hard affinity and the cpus in its cpupool.

I think for now I might advise putting off doing a NUMA interface at the
libxl level, and do a full vNUMA interface in another series (perhaps
for 4.5, depending on the timing).

Well, I agree that all this is of very little use without vNUMA, but at
the same time, it's not necessarily only useful for it. Also, whatever
it is vcpu-node-affinity or soft-affinity, if it is not wired up
properly up to the higher layers, there's very few point of having the
HV part only... So my idea was to redo and resend everything, including
libxl and xl bits.

Of course, that doesn't mean we must necessarily have this for 4.4
(although I think it would still be feasible), just that we either
check-in or wait for both the implementation and the interface. Again,
how's the updated release schedule?

Well we definitely should plumb through access to the soft affinity directly through libxl. The question is whether it would be useful to have a libxl per-vcpu *numa* affinity that is not yet a full vNUMA implementation. If long-term we want to have vcpu -> vnode, and then vnode->pnode, the having a direct vcpu->pnode interface in the interim is probably not particularly useful, I don't think.

Re the release schedule: we agreed to move the code freeze to November 18, so we've got just under two weeks. I think keeping the libxl side simple will allow us to at least get the "soft affinity" stuff in for 4.4, whether the vNUMA stuff makes it or not.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.