Re: [Xen-devel] RE: [ PATCH 4/4 ] HVM vcpu add/remove: qemu logic for vcpu add/revmoe

[Michal Novotny <minovotn@xxxxxxxxxx>]

On 12/14/2009 10:54 AM, Liu, Jinsong wrote:
> Keir Fraser wrote:
>    
> > On 14/12/2009 08:04, "Keir Fraser"<keir.fraser@xxxxxxxxxxxxx>  wrote:
> >
> >      
> > > On 13/12/2009 18:05, "Liu, Jinsong"<jinsong.liu@xxxxxxxxx>  wrote:
> > >
> > >        
> > > > HVM vcpu add/remove: qemu logic for vcpu add/revmoe
> > > >
> > > > -- at qemu side, get vcpu_avail which used for original cpu avail
> > > > map;
> > > > -- setup gpe ioread/iowrite at qmeu;
> > > > -- setup vcpu add/remove user interface through monitor;
> > > > -- setup SCI logic;
> > > >          
> > > I'm guessing because this adds a new command-line option that I need
> > > this checked into the qemu tree before I can apply your first patch
> > > (1/4)? Otherwise that patch will break domain creation as qemu will
> > > exit with an 'unrecognised option' error. So I need Ian Jackson to
> > > apply this one and send me an updated QEMU_TAG first.
> > >        
> > As of c/s 20640 all your Xen patches are checked in. I modified them
> > a bit so you may want to take a look. I commented out the one line
> > that actually sets the new qemu option, until that option is
> > supported by our qemu. I think there is a question over whether the
> > new qemu option should (a) have a better name (I called it
> > vcpu_online[] in hvm_info structure); and (b) should have a more
> > user-friendly format (currently passing a decimal number interpreted
> > as a bitmap - perhaps should be a list of vcpus instead).
> >
> >   -- Keir
> >      
> Thanks!
>
> Currently at xm level, HVM config keep compatible with PV config (patch 20495, 
> 20502), they both set maxvcpus/ avail vcpus at config file as
> maxvcpus = xxx
> vcpus = yyy
> and both HVM and PV can dynamic add/remove vcpus now.
>
> One question is, patch 20384/ 20386/ 20389 and qemu patch 
> 3140780e451d3919ef2c81f91ae0ebe3f286eb06 extend HVM vcpus max to 128, however, 
> current xm and xend python logic seems only support max 64 since xm/xend now 
> interpret vcpu bitmap to a 'long'.
> I agree that the bitmap would better be replaced by a list of vcpus so that 
> vcpus number will not be limited in the future.
>    
Well, actually I did the patches 20495 and 20502 and I used the existing 
infrastructure of vcpus and vcpu_avail here so there were no changes in 
current infrastructure since I wanted to preserve it. That's the reason 
why my patch was done this way. Changing existing infrastructure could 
introduce some problems with that so that's why maxvcpus values is going 
to be vcpus in xend python as well as vcpus is set the bitmask of 
vcpu_avail.
Regards,
Michal
> Regards,
> Jinsong
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>    
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