Re: [Xen-devel] [PATCH RESEND v7 1/9] xen: vnuma topology and subop hypercalls

[Elena Ufimtseva <ufimtseva@xxxxxxxxx>]

On Fri, Aug 22, 2014 at 9:54 AM, Dario Faggioli
<dario.faggioli@xxxxxxxxxx> wrote:
> On ven, 2014-08-22 at 14:17 +0100, Jan Beulich wrote:
>
>> > +    if ( ret )
>> > +        return ret;
>> > +
>> > +    ret = -EFAULT;
>> > +
>> > +    if ( copy_from_guest(v->vdistance, u_vnuma->vdistance,
>> > +                         nr_vnodes * nr_vnodes) )
>> > +        goto vnuma_fail;
>> > +
>> > +    if ( copy_from_guest(v->vmemrange, u_vnuma->vmemrange, nr_vnodes) )
>> > +        goto vnuma_fail;
>>
>> Isn't a single memory range per vnode rather limiting? Physical
>> machines frequently have at least one node with two ranges to
>> accommodate the hole below 4Gb. And since the interface is for
>> all guest kinds I'm afraid this will harm setting up guests rather
>> sooner than later. (I'm sorry for thinking of this only now.)
>>
> This actually was one concern of mine too, during the early stage of
> Elena's work. I clearly remember wondering, and even asking, considering
> that Linux uses more ranges per node, why using only one was ok for us.
>
> Unfortunately, I OTOH forgot how that discussion ended and how we got to
> this point, without me or anyone else (continuing to) complaining... So,
> sorry from me too. :-(
>
> Let's see what Elena and others think and, after that, how big of a
> piece of work is to introduce support for more than one ranges (or
> re-introduce, as I also think I remember this to be some kind of list,
> during early versions of the series).
>
> Regards,
> Dario
>
> --
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
>


Jan, Dario

Thank you for review. I briefly read them and I will give it a more
through read after work.

As for many-regions nodes, I will give it a thought as there maybe a
simple extension to memory structure.

I will try to evaluate asap and reply.

Elena
-- 
Elena

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