Re: [Xen-devel] [PATCH v7 07/14] x86: dynamically get/set CBM for a domain

[Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>]

On Thu, May 14, 2015 at 11:19:17AM +0200, Dario Faggioli wrote:
> On Fri, 2015-05-08 at 16:56 +0800, Chao Peng wrote:
> > For CAT, COS is maintained in hypervisor only while CBM is exposed to
> > user space directly to allow getting/setting domain's cache capacity.
> > For each specified CBM, hypervisor will either use a existed COS which
> > has the same CBM or allocate a new one if the same CBM is not found. If
> > the allocation fails because of no enough COS available then error is
> > returned. The getting/setting are always operated on a specified socket.
> > For multiple sockets system, the interface may be called several times.
> > 
> > Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> >
> Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> 
> Just, one minor thing, only if you end up resending...
> 
> > diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
> > index 1feb2f6..385807b 100644
> > --- a/xen/arch/x86/psr.c
> > +++ b/xen/arch/x86/psr.c
> > @@ -49,6 +49,14 @@ static unsigned int opt_cos_max = 255;
> >  static uint64_t rmid_mask;
> >  static DEFINE_PER_CPU(struct psr_assoc, psr_assoc);
> >  
> > +static unsigned int get_socket_cpu(unsigned int socket)
> > +{
> > +    if ( socket < nr_sockets )
> > +        return cpumask_any(socket_to_cpumask[socket]);
> > +
> ... What about 
> 
>   if ( likely(socket < nr_sockets) )

Agreed, it can be an optimization chance.

Let's see what others think.

Thanks for review.
Chao

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