Re: [PATCH V5 03/32] xl / libxl: push VCPU affinity pinning down to libxl

[Dario Faggioli <dario.faggioli@citrix.com>]

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On gio, 2014-05-15 at 18:06 +0100, Wei Liu wrote:
> On Thu, May 15, 2014 at 05:45:19PM +0100, Ian Campbell wrote:
> > On Tue, 2014-05-13 at 22:53 +0100, Wei Liu wrote:
> > 
> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > > index 0dfafe7..7b0901c 100644
> > > --- a/tools/libxl/libxl_types.idl
> > > +++ b/tools/libxl/libxl_types.idl
> > > @@ -305,6 +305,7 @@ libxl_domain_build_info =
> > Struct("domain_build_info",[
> > >      ("avail_vcpus",     libxl_bitmap),
> > >      ("cpumap",          libxl_bitmap),
> > >      ("nodemap",         libxl_bitmap),
> > > +    ("vcpu_affinity",   libxl_key_value_list),
> > > 
> > Is a key value list really the best way to represent this? At first
> > glance it seems like an array would be more suitable?
> > 
> > I've glanced through the rest on the assumption you have a convincing
> > reason why it should be a kvp list.
> > 
> 
> How can you effectively skip pinning a VCPU if it's an array? I can have
> [ '0': '1', '3': '3' ] in KVL, but not able to represent it in an array
> [ '1', ?, ?, '3' ].
> 
I think I agree with Wei.

When everything was in xl, an array is what was being used, marking with
'-1' (IIRC) the spots of not-to-be-pinned vcpus.

Now that we're passing the info to libxl, that would mean always passing
an array of max_vcpus elements, even if the to-be-pinned vcpus are only
2 or 3.

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)


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