Re: [PATCH 1/2] drm/i915: Extend GET_APERTURE ioctl to report available map space

[Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>]

On Wed, 2015-07-01 at 15:39 +0200, Daniel Vetter wrote:
> On Wed, Jul 01, 2015 at 02:55:12PM +0530, ankitprasad.r.sharma@intel.com wrote:
> > From: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > 
> > When constructing a batchbuffer, it is sometimes crucial to know the
> > largest hole into which we can fit a fenceable buffer (for example when
> > handling very large objects on gen2 and gen3). This depends on the
> > fragmentation of pinned buffers inside the aperture, a question only the
> > kernel can easily answer.
> > 
> > This patch extends the current DRM_I915_GEM_GET_APERTURE ioctl to
> > include a couple of new fields in its reply to userspace - the total
> > amount of space available in the mappable region of the aperture and
> > also the single largest block available.
> > 
> > This is not quite what userspace wants to answer the question of whether
> > this batch will fit as fences are also required to meet severe alignment
> > constraints within the batch. For this purpose, a third conservative
> > estimate of largest fence available is also provided. For when userspace
> > needs more than one batch, we also provide the culmulative space
> > available for fences such that it has some additional guidance to how
> > much space it could allocate to fences. Conservatism still wins.
> > 
> > The patch also adds a debugfs file for convenient testing and reporting.
> > 
> > v2: The first object cannot end at offset 0, so we can use last==0 to
> > detect the empty list.
> > 
> > v3: Expand all values to 64bit, just in case.
> >     Report total mappable aperture size for userspace that cannot easily
> >     determine it by inspecting the PCI device.
> > 
> > v4: (Rodrigo) Fixed rebase conflicts.
> > 
> > v5: Rebased to the latest drm-intel-nightly (Ankit)
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_debugfs.c |  27 +++++++++
> >  drivers/gpu/drm/i915/i915_gem.c     | 116 ++++++++++++++++++++++++++++++++++--
> >  2 files changed, 139 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > index 31d8768..49ec438 100644
> > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > @@ -512,6 +512,32 @@ static int i915_gem_object_info(struct seq_file *m, void* data)
> >  	return 0;
> >  }
> >  
> > +static int i915_gem_aperture_info(struct seq_file *m, void *data)
> > +{
> > +	struct drm_info_node *node = m->private;
> > +	struct drm_i915_gem_get_aperture arg;
> > +	int ret;
> > +
> > +	ret = i915_gem_get_aperture_ioctl(node->minor->dev, &arg, NULL);
> > +	if (ret)
> > +		return ret;
> > +
> > +	seq_printf(m, "Total size of the GTT: %llu bytes\n",
> > +		   arg.aper_size);
> > +	seq_printf(m, "Available space in the GTT: %llu bytes\n",
> > +		   arg.aper_available_size);
> > +	seq_printf(m, "Available space in the mappable aperture: %llu bytes\n",
> > +		   arg.map_available_size);
> > +	seq_printf(m, "Single largest space in the mappable aperture: %llu bytes\n",
> > +		   arg.map_largest_size);
> > +	seq_printf(m, "Available space for fences: %llu bytes\n",
> > +		   arg.fence_available_size);
> > +	seq_printf(m, "Single largest fence available: %llu bytes\n",
> > +		   arg.fence_largest_size);
> > +
> > +	return 0;
> > +}
> > +
> >  static int i915_gem_gtt_info(struct seq_file *m, void *data)
> >  {
> >  	struct drm_info_node *node = m->private;
> > @@ -5030,6 +5056,7 @@ static int i915_debugfs_create(struct dentry *root,
> >  static const struct drm_info_list i915_debugfs_list[] = {
> >  	{"i915_capabilities", i915_capabilities, 0},
> >  	{"i915_gem_objects", i915_gem_object_info, 0},
> > +	{"i915_gem_aperture", i915_gem_aperture_info, 0},
> >  	{"i915_gem_gtt", i915_gem_gtt_info, 0},
> >  	{"i915_gem_pinned", i915_gem_gtt_info, 0, (void *) PINNED_LIST},
> >  	{"i915_gem_active", i915_gem_object_list_info, 0, (void *) ACTIVE_LIST},
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index a2a4a27..ccfc8d3 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -32,6 +32,7 @@
> >  #include "i915_vgpu.h"
> >  #include "i915_trace.h"
> >  #include "intel_drv.h"
> > +#include <linux/list_sort.h>
> >  #include <linux/shmem_fs.h>
> >  #include <linux/slab.h>
> >  #include <linux/swap.h>
> > @@ -143,6 +144,55 @@ int i915_mutex_lock_interruptible(struct drm_device *dev)
> >  	return 0;
> >  }
> >  
> > +static inline bool
> > +i915_gem_object_is_inactive(struct drm_i915_gem_object *obj)
> > +{
> > +	return i915_gem_obj_bound_any(obj) && !obj->active;
> > +}
> > +
> > +static int obj_rank_by_ggtt(void *priv,
> > +			    struct list_head *A,
> > +			    struct list_head *B)
> > +{
> > +	struct drm_i915_gem_object *a = list_entry(A,typeof(*a), obj_exec_link);
> > +	struct drm_i915_gem_object *b = list_entry(B,typeof(*b), obj_exec_link);
> > +
> > +	return i915_gem_obj_ggtt_offset(a) - i915_gem_obj_ggtt_offset(b);
> > +}
> > +
> > +static u32 __fence_size(struct drm_i915_private *dev_priv, u32 start, u32 end)
> > +{
> > +	u32 size = end - start;
> > +	u32 fence_size;
> > +
> > +	if (INTEL_INFO(dev_priv)->gen < 4) {
> > +		u32 fence_max;
> > +		u32 fence_next;
> > +
> > +		if (IS_GEN3(dev_priv)) {
> > +			fence_max = I830_FENCE_MAX_SIZE_VAL << 20;
> > +			fence_next = 1024*1024;
> > +		} else {
> > +			fence_max = I830_FENCE_MAX_SIZE_VAL << 19;
> > +			fence_next = 512*1024;
> > +		}
> > +
> > +		fence_max = min(fence_max, size);
> > +		fence_size = 0;
> > +		while (fence_next <= fence_max) {
> > +			u32 base = ALIGN(start, fence_next);
> > +			if (base + fence_next > end)
> > +				break;
> > +
> > +			fence_size = fence_next;
> > +			fence_next <<= 1;
> > +		}
> > +	} else
> > +		fence_size = size;
> > +
> > +	return fence_size;
> > +}
> > +
> >  int
> >  i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
> >  			    struct drm_file *file)
> > @@ -150,17 +200,75 @@ i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> >  	struct drm_i915_gem_get_aperture *args = data;
> >  	struct drm_i915_gem_object *obj;
> > -	size_t pinned;
> > +	struct list_head map_list;
> > +	const u32 map_limit = dev_priv->gtt.mappable_end;
> > +	size_t pinned, map_space, map_largest, fence_space, fence_largest;
> > +	u32 last, size;
> > +
> > +	INIT_LIST_HEAD(&map_list);
> >  
> >  	pinned = 0;
> > +	map_space = map_largest = 0;
> > +	fence_space = fence_largest = 0;
> > +
> >  	mutex_lock(&dev->struct_mutex);
> > -	list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list)
> > -		if (i915_gem_obj_is_pinned(obj))
> > -			pinned += i915_gem_obj_ggtt_size(obj);
> > +	list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
> > +		struct i915_vma *vma = i915_gem_obj_to_ggtt(obj);
> > +
> > +		if (vma == NULL || !vma->pin_count)
> > +			continue;
> > +
> > +		pinned += vma->node.size;
> > +
> > +		if (vma->node.start < map_limit)
> > +			list_add(&obj->obj_exec_link, &map_list);
> > +	}
> > +
> > +	last = 0;
> > +	list_sort(NULL, &map_list, obj_rank_by_ggtt);
> > +	while (!list_empty(&map_list)) {
> > +		struct i915_vma *vma;
> > +
> > +		obj = list_first_entry(&map_list, typeof(*obj), obj_exec_link);
> > +		list_del_init(&obj->obj_exec_link);
> > +
> > +		vma = i915_gem_obj_to_ggtt(obj);
> > +		if (last == 0)
> > +			goto skip_first;
> > +
> > +		size = vma->node.start - last;
> > +		if (size > map_largest)
> > +			map_largest = size;
> > +		map_space += size;
> > +
> > +		size = __fence_size(dev_priv, last, vma->node.start);
> > +		if (size > fence_largest)
> > +			fence_largest = size;
> > +		fence_space += size;
> > +
> > +skip_first:
> > +		last = vma->node.start + vma->node.size;
> > +	}
> > +	if (last < map_limit) {
> > +		size = map_limit - last;
> > +		if (size > map_largest)
> > +			map_largest = size;
> > +		map_space += size;
> > +
> > +		size = __fence_size(dev_priv, last, map_limit);
> > +		if (size > fence_largest)
> > +			fence_largest = size;
> > +		fence_space += size;
> > +	}
> >  	mutex_unlock(&dev->struct_mutex);
> >  
> >  	args->aper_size = dev_priv->gtt.base.total;
> >  	args->aper_available_size = args->aper_size - pinned;
> > +	args->map_available_size = map_space;
> > +	args->map_largest_size = map_largest;
> > +	args->map_total_size = dev_priv->gtt.mappable_end;
> > +	args->fence_available_size = fence_space;
> > +	args->fence_largest_size = fence_largest;
> 
> Does this really compile? You only add all the new structure stuff in the
> 2nd patch.
> -Daniel
No, it does not. That is my bad. Some confusion with the patches. Need
to rebase again, carefully. 
-Thanks, Ankit
> 
> >  
> >  	return 0;
> >  }
> > -- 
> > 1.9.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 


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