Re: [PATCH 4/4] drm/i915: Use eb for more stuff

[Chris Wilson <chris@chris-wilson.co.uk>]

On Thu, 13 Oct 2011 10:58:25 +0200, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Wed, Oct 12, 2011 at 03:56:22PM -0700, Ben Widawsky wrote:
> > This refactor is useful for some future work I'll be doing on the
> > execbuffer path. In addition to being a pretty easy prerequisite, it
> > also helped me track down the bug uncovered in the first patch.
> > 
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  102 ++++++++++++++--------------
> >  1 files changed, 51 insertions(+), 51 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> > index 182a2b9..b3beaae 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> > @@ -40,6 +40,16 @@ struct change_domains {
> >  	uint32_t flips;
> >  };
> >  
> > +struct eb_objects {
> > +	struct drm_i915_gem_object *batch_obj;
> > +	struct list_head objects;
> > +	int buffer_count;
> > +	int mode;
> > +	int and;
> 
> While you whack this code, can you do an s/and/end, I think that's just a
> typo ...

It was meant to be 'and' since it was the value of the mask I was anding
with. I'm sorry I appear to have spent too much time inside the Xserver,
end = and + 1.
> 
> > +	struct hlist_head buckets[0];
> > +	/* DO NOT PUT ANYTHING HERE */
> 
> When you drop the array size, the compiler will enforce that for you (for
> $compiler = gcc at least).

I wanted to say that surely the comment was obvious from the '[0]' ;-)

> 
> > +};
> > +
> >  /*
> >   * Set the next domain for the specified object. This
> >   * may not actually perform the necessary flushing/invaliding though,
> > @@ -207,11 +217,6 @@ i915_gem_object_set_to_gpu_domain(struct drm_i915_gem_object *obj,
> >  		cd->flush_rings |= ring->id;
> >  }
> >  
> > -struct eb_objects {
> > -	int and;
> > -	struct hlist_head buckets[0];
> > -};
> > -
> >  static struct eb_objects *
> >  eb_create(int size)
> >  {
> > @@ -225,6 +230,8 @@ eb_create(int size)
> >  	if (eb == NULL)
> >  		return eb;
> >  
> > +	INIT_LIST_HEAD(&eb->objects);
> > +
> >  	eb->and = count - 1;
> >  	return eb;
> >  }
> > @@ -232,12 +239,22 @@ eb_create(int size)
> >  static void
> >  eb_reset(struct eb_objects *eb)
> >  {
> > +	while (!list_empty(&eb->objects)) {
> 
> list_for_each_entry_safe

No, the while (!empty) is the more common and much simpler idiom to use
here when clearing a list.

> > -	mode = args->flags & I915_EXEC_CONSTANTS_MASK;
> > -	ret = i915_gem_set_constant_offset(ring, mode);
> > +	eb->mode = args->flags & I915_EXEC_CONSTANTS_MASK;
> > +	ret = i915_gem_set_constant_offset(ring, eb->mode);
> 
> The eb->mode refactor here otoh looks a bit superflous. Is this needed for
> a future patch of yours?

I'm waiting to see how this pans out as well... ;-)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre