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Re: [Xen-devel] PV-vNUMA issue: topology is misinterpreted by the guest

On 07/27/2015 04:34 PM, Boris Ostrovsky wrote:
On 07/27/2015 10:09 AM, Dario Faggioli wrote:
On Fri, 2015-07-24 at 18:10 +0200, Juergen Gross wrote:
On 07/24/2015 05:58 PM, Dario Faggioli wrote:
So, just to check if I'm understanding is correct: you'd like to add an
abstraction layer, in Linux, like in generic (or, perhaps, scheduling)
code, to hide the direct interaction with CPUID.
Such layer, on baremetal, would just read CPUID while, on PV-ops, it'd
check with Xen/match vNUMA/whatever... Is this that you are saying?
Sort of, yes.

I just wouldn't add it, as it is already existing (more or less). It
can deal right now with AMD and Intel, we would "just" have to add Xen.

So, having gone through the rest of the thread (so far), and having
given a fair amount o thinking to this, I really think that something
like this would be a good thing to have in Linux.

Of course, it's not that my opinion on where should be in Linux counts
that much! :-D   Nevertheless, I wanted to make it clear that, while
skeptic at the beginning, I now think this is (part of) the way to go,
as I said and explained in my reply to George.

And I continue to believe that kernel solution does not address the
userland problem which is no less important than making kernel do proper
scheduling decisions (and I suspect when this patch goes for review
that's what the scheduling people are going to say).

I didn't say it would solve that problem. It would decouple kernel
scheduling and cpuid values in order to be free to present cpuid values
to user land needed there.


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