[Intel-gfx] [PATCH 01/15] drm/i915: Add ctx getparam ioctl parameter to retrieve ctx unique id

[Chris Wilson]

On Wed, Jul 27, 2016 at 12:19:00PM +0200, Daniel Vetter wrote:
> On Wed, Jul 27, 2016 at 02:48:38PM +0530, Deepak wrote:
> > 
> > 
> > 
> > On 06/02/2016 10:48 AM, sourab.gupta at intel.com wrote:
> > > From: Sourab Gupta <sourab.gupta at intel.com>
> > > 
> > > This patch adds a new ctx getparam ioctl parameter, which can be used to
> > > retrieve ctx unique id by userspace.
> > > 
> > > This can be used by userspace to map the i915 perf samples with their
> > > particular ctx's, since those would be having ctx unique id's.
> > > Otherwise the userspace has no way of maintaining this association,
> > > since it has the knowledge of only per-drm file specific ctx handles.
> > > 
> > > Signed-off-by: Sourab Gupta <sourab.gupta at intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/i915_gem_context.c | 3 +++
> > >   include/uapi/drm/i915_drm.h             | 1 +
> > >   2 files changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> > > index e974451..09f5178 100644
> > > --- a/drivers/gpu/drm/i915/i915_gem_context.c
> > > +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> > > @@ -1001,6 +1001,9 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
> > >   		else
> > >   			args->value = to_i915(dev)->ggtt.base.total;
> > >   		break;
> > > +	case I915_CONTEXT_PARAM_HW_ID:
> > > +		args->value = ctx->hw_id;
> > > +		break;
> > >   	default:
> > >   		ret = -EINVAL;
> > >   		break;
> > > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> > > index 4a1bcfd8..0badc16 100644
> > > --- a/include/uapi/drm/i915_drm.h
> > > +++ b/include/uapi/drm/i915_drm.h
> > > @@ -1171,6 +1171,7 @@ struct drm_i915_gem_context_param {
> > >   #define I915_CONTEXT_PARAM_BAN_PERIOD	0x1
> > >   #define I915_CONTEXT_PARAM_NO_ZEROMAP	0x2
> > >   #define I915_CONTEXT_PARAM_GTT_SIZE	0x3
> > > +#define I915_CONTEXT_PARAM_HW_ID	0x4
> > >   	__u64 value;
> > >   };
> > Patch looks good to me
> > 
> > Reviewed-by: Deepak S <deepak.s at linux.intel.com>
> 
> ctx->hw_id gets recycled without any involvement from userspace. How
> exactly is this supposed to work?

ctx->hw_id is invariant for the lifetime of the context (and so we limit
the number of live contents to meet hw constraints, ~1 million).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre