[Intel-gfx] [PATCH] drm/i915/gvt: return the actual aperture size under gvt environment

[Li, Weinan Z]

> -----Original Message-----
> From: Joonas Lahtinen [mailto:joonas.lahtinen at linux.intel.com]
> Sent: Wednesday, April 12, 2017 6:19 PM
> To: Chris Wilson <chris at chris-wilson.co.uk>; Li, Weinan Z
> <weinan.z.li at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; intel-gvt-dev at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/gvt: return the actual aperture size
> under gvt environment
> 
> On ke, 2017-04-12 at 09:53 +0100, Chris Wilson wrote:
> > On Wed, Apr 12, 2017 at 04:36:57PM +0800, Weinan Li wrote:
> > >
> > > I915_GEM_GET_APERTURE ioctl is used to probe aperture size from
> userspace.
> > > Some applications like OpenCL use this information to know how much
> > > GM resource can it use.
> >
> > That's a userspace bug.
> 
> Yes, a new property might be in place. I don't think we can go and change the
> meaning of a parameter just like that.
> 
> <SNIP>
> 
Here I don’t want to change the meaning of I915_GEM_GET_APERTURE, but for the ioctl,
We need to return the actual available aperture size exclude the reserved space by GVT balloon.

> > > @@ -116,6 +121,14 @@ void intel_vgt_deballoon(struct drm_i915_private
> *dev_priv)
> > >  	memset(&bl_info, 0, sizeof(bl_info));
> > >  }
> > >
> > > +size_t intel_vgt_reserved_size_by_balloon(struct drm_i915_private
> > > +*dev_priv) {
> > > +	if (!intel_vgpu_active(dev_priv))
> > > +		return 0;
> > > +
> > > +	return bl_info.reserved_total;
> > > +}
> >
> > Or just return bl_info.reserved_total.
> >
> > Why is there a global here anyway?
> >
> > Better would be to track dev_priv->ggtt.reserved
> >
> > Then the core code becomes
> > 	gtt_size = dev_priv->ggtt.total - dev_priv->ggtt.reserved;
> >
> > and doesn't need to know the identity of every possible consumer.
> 
> I was writing an e-mail about the same thing. So +1 on the idea.
> 
Agreed.
> Regards, Joonas
> --
> Joonas Lahtinen
> Open Source Technology Center
> Intel Corporation