Re: [PATCH for Xen 4.6 3/5] tools/libxl: return socket id from libxl_psr_cat_get_l3_info

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

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On Mon, 2015-09-28 at 15:13 +0100, Wei Liu wrote:
> On Mon, Sep 28, 2015 at 07:54:51PM +0800, Chao Peng wrote:

> > diff --git a/tools/libxl/libxl_psr.c b/tools/libxl/libxl_psr.c
> > index 3378239..10e1113 100644

> > @@ -339,7 +339,8 @@ int libxl_psr_cat_get_l3_info(libxl_ctx *ctx,
> > libxl_psr_cat_info **info,
> >  {
> >      GC_INIT(ctx);
> >      int rc;
> > -    int i, nr_sockets;
> > +    int i = 0, socket, nr_sockets;
> > +    libxl_bitmap socketmap;
> >      libxl_psr_cat_info *ptr;
> >  
> >      rc = libxl__count_physical_sockets(gc, &nr_sockets);
> > @@ -348,21 +349,31 @@ int libxl_psr_cat_get_l3_info(libxl_ctx *ctx,
> > libxl_psr_cat_info **info,
> >          goto out;
> >      }
> 
> This is a path that you call libxl_bitmap_dispose on an uninitialised
> socketmap.
> 
Yep.

However, do we still need to go through libxl__count_physical_sockets()
explicitly? AFAICS, you need it for allocating ptr, and for returning
it back.

But since now you're building the full bitmap, we can use
libxl_bitmap_count_set(), for that.

This may not be a bit deal, but if I'm not wrong, it saves us an
hypercall (the PHYSINFO that libxl__count_physical_socket() issues).

> > --- a/tools/libxl/libxl_types.idl
> > +++ b/tools/libxl/libxl_types.idl
> > @@ -792,6 +792,7 @@ libxl_psr_cbm_type =
> > Enumeration("psr_cbm_type", [
> >      ])
> >  
> >  libxl_psr_cat_info = Struct("psr_cat_info", [
> > +    ("target_id", uint32),
> 
> Or just call it "socket_id"? Or even just "id" because you know this
> structure is for socket?
> 
Yeah, we discussed this already, AFAICR. I think the point is that, at
least in theory, these features may be extended to become more fine
-grained than per-socket, hence the point of not binding the interface
to sockets.

That being said, FWIW, I'm fine either way.

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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