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drm/i915: Allow userspace to hint that the relocations were known
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Userspace is able to hint to the kernel that its command stream and
auxiliary state buffers already hold the correct presumed addresses and
so the relocation process may be skipped if the kernel does not need to
move any buffers in preparation for the execbuffer. Thus for the common
case where the allotment of buffers is static between batches, we can
avoid the overhead of individually checking the relocation entries.

Note that this requires userspace to supply the domain tracking and
requests for workarounds itself that would otherwise be computed based
upon the relocation entries.

Using copywinwin10 as an example that is dependent upon emitting a lot
of relocations (2 per operation), we see improvements of:

c2d/gm45: 618000.0/sec to 632000.0/sec.
i3-330m: 748000.0/sec to 830000.0/sec.

(measured relative to a baseline with neither optimisations applied).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Imre Deak <imre.deak@intel.com>
[danvet: Fixup merge conflict in userspace header due to different
baseline trees.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Daniel Vetter committed Jan 17, 2013
1 parent bcffc3f commit ed5982e
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Showing 3 changed files with 62 additions and 23 deletions.
3 changes: 3 additions & 0 deletions drivers/gpu/drm/i915/i915_dma.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -992,6 +992,9 @@ static int i915_getparam(struct drm_device *dev, void *data,
case I915_PARAM_HAS_PINNED_BATCHES:
value = 1;
break;
case I915_PARAM_HAS_EXEC_NO_RELOC:
value = 1;
break;
default:
DRM_DEBUG_DRIVER("Unknown parameter %d\n",
param->param);
Expand Down
68 changes: 45 additions & 23 deletions drivers/gpu/drm/i915/i915_gem_execbuffer.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -373,7 +373,8 @@ need_reloc_mappable(struct drm_i915_gem_object *obj)

static int
i915_gem_execbuffer_reserve_object(struct drm_i915_gem_object *obj,
struct intel_ring_buffer *ring)
struct intel_ring_buffer *ring,
bool *need_reloc)
{
struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
Expand Down Expand Up @@ -414,7 +415,20 @@ i915_gem_execbuffer_reserve_object(struct drm_i915_gem_object *obj,
obj->has_aliasing_ppgtt_mapping = 1;
}

entry->offset = obj->gtt_offset;
if (entry->offset != obj->gtt_offset) {
entry->offset = obj->gtt_offset;
*need_reloc = true;
}

if (entry->flags & EXEC_OBJECT_WRITE) {
obj->base.pending_read_domains = I915_GEM_DOMAIN_RENDER;
obj->base.pending_write_domain = I915_GEM_DOMAIN_RENDER;
}

if (entry->flags & EXEC_OBJECT_NEEDS_GTT &&
!obj->has_global_gtt_mapping)
i915_gem_gtt_bind_object(obj, obj->cache_level);

return 0;
}

Expand All @@ -440,7 +454,8 @@ i915_gem_execbuffer_unreserve_object(struct drm_i915_gem_object *obj)
static int
i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
struct drm_file *file,
struct list_head *objects)
struct list_head *objects,
bool *need_relocs)
{
struct drm_i915_gem_object *obj;
struct list_head ordered_objects;
Expand Down Expand Up @@ -468,7 +483,7 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
else
list_move_tail(&obj->exec_list, &ordered_objects);

obj->base.pending_read_domains = 0;
obj->base.pending_read_domains = I915_GEM_GPU_DOMAINS & ~I915_GEM_DOMAIN_COMMAND;
obj->base.pending_write_domain = 0;
obj->pending_fenced_gpu_access = false;
}
Expand Down Expand Up @@ -508,7 +523,7 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
(need_mappable && !obj->map_and_fenceable))
ret = i915_gem_object_unbind(obj);
else
ret = i915_gem_execbuffer_reserve_object(obj, ring);
ret = i915_gem_execbuffer_reserve_object(obj, ring, need_relocs);
if (ret)
goto err;
}
Expand All @@ -518,7 +533,7 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
if (obj->gtt_space)
continue;

ret = i915_gem_execbuffer_reserve_object(obj, ring);
ret = i915_gem_execbuffer_reserve_object(obj, ring, need_relocs);
if (ret)
goto err;
}
Expand All @@ -538,16 +553,18 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,

static int
i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
struct drm_i915_gem_execbuffer2 *args,
struct drm_file *file,
struct intel_ring_buffer *ring,
struct eb_objects *eb,
struct drm_i915_gem_exec_object2 *exec,
int count)
struct drm_i915_gem_exec_object2 *exec)
{
struct drm_i915_gem_relocation_entry *reloc;
struct drm_i915_gem_object *obj;
bool need_relocs;
int *reloc_offset;
int i, total, ret;
int count = args->buffer_count;

/* We may process another execbuffer during the unlock... */
while (!list_empty(&eb->objects)) {
Expand Down Expand Up @@ -602,7 +619,8 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
if (ret)
goto err;

ret = i915_gem_execbuffer_reserve(ring, file, &eb->objects);
need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
ret = i915_gem_execbuffer_reserve(ring, file, &eb->objects, &need_relocs);
if (ret)
goto err;

Expand Down Expand Up @@ -660,6 +678,9 @@ i915_gem_execbuffer_move_to_gpu(struct intel_ring_buffer *ring,
static bool
i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec)
{
if (exec->flags & __I915_EXEC_UNKNOWN_FLAGS)
return false;

return ((exec->batch_start_offset | exec->batch_len) & 0x7) == 0;
}

Expand All @@ -673,16 +694,16 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
char __user *ptr = (char __user *)(uintptr_t)exec[i].relocs_ptr;
int length; /* limited by fault_in_pages_readable() */

if (exec[i].flags & __EXEC_OBJECT_UNKNOWN_FLAGS)
return -EINVAL;

/* First check for malicious input causing overflow */
if (exec[i].relocation_count >
INT_MAX / sizeof(struct drm_i915_gem_relocation_entry))
return -EINVAL;

length = exec[i].relocation_count *
sizeof(struct drm_i915_gem_relocation_entry);
if (!access_ok(VERIFY_READ, ptr, length))
return -EFAULT;

/* we may also need to update the presumed offsets */
if (!access_ok(VERIFY_WRITE, ptr, length))
return -EFAULT;
Expand All @@ -704,8 +725,10 @@ i915_gem_execbuffer_move_to_active(struct list_head *objects,
u32 old_read = obj->base.read_domains;
u32 old_write = obj->base.write_domain;

obj->base.read_domains = obj->base.pending_read_domains;
obj->base.write_domain = obj->base.pending_write_domain;
if (obj->base.write_domain == 0)
obj->base.pending_read_domains |= obj->base.read_domains;
obj->base.read_domains = obj->base.pending_read_domains;
obj->fenced_gpu_access = obj->pending_fenced_gpu_access;

i915_gem_object_move_to_active(obj, ring);
Expand Down Expand Up @@ -770,14 +793,12 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
struct intel_ring_buffer *ring;
u32 ctx_id = i915_execbuffer2_get_context_id(*args);
u32 exec_start, exec_len;
u32 mask;
u32 flags;
u32 mask, flags;
int ret, mode, i;
bool need_relocs;

if (!i915_gem_check_execbuffer(args)) {
DRM_DEBUG("execbuf with invalid offset/length\n");
if (!i915_gem_check_execbuffer(args))
return -EINVAL;
}

ret = validate_exec_list(exec, args->buffer_count);
if (ret)
Expand Down Expand Up @@ -916,17 +937,18 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
exec_list);

/* Move the objects en-masse into the GTT, evicting if necessary. */
ret = i915_gem_execbuffer_reserve(ring, file, &eb->objects);
need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
ret = i915_gem_execbuffer_reserve(ring, file, &eb->objects, &need_relocs);
if (ret)
goto err;

/* The objects are in their final locations, apply the relocations. */
ret = i915_gem_execbuffer_relocate(dev, eb);
if (need_relocs)
ret = i915_gem_execbuffer_relocate(dev, eb);
if (ret) {
if (ret == -EFAULT) {
ret = i915_gem_execbuffer_relocate_slow(dev, file, ring,
eb, exec,
args->buffer_count);
ret = i915_gem_execbuffer_relocate_slow(dev, args, file, ring,
eb, exec);
BUG_ON(!mutex_is_locked(&dev->struct_mutex));
}
if (ret)
Expand Down
14 changes: 14 additions & 0 deletions include/uapi/drm/i915_drm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -308,6 +308,7 @@ typedef struct drm_i915_irq_wait {
#define I915_PARAM_RSVD_FOR_FUTURE_USE 22
#define I915_PARAM_HAS_SECURE_BATCHES 23
#define I915_PARAM_HAS_PINNED_BATCHES 24
#define I915_PARAM_HAS_EXEC_NO_RELOC 25

typedef struct drm_i915_getparam {
int param;
Expand Down Expand Up @@ -628,7 +629,11 @@ struct drm_i915_gem_exec_object2 {
__u64 offset;

#define EXEC_OBJECT_NEEDS_FENCE (1<<0)
#define EXEC_OBJECT_NEEDS_GTT (1<<1)
#define EXEC_OBJECT_WRITE (1<<2)
#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_WRITE<<1)
__u64 flags;

__u64 rsvd1;
__u64 rsvd2;
};
Expand Down Expand Up @@ -687,6 +692,15 @@ struct drm_i915_gem_execbuffer2 {
*/
#define I915_EXEC_IS_PINNED (1<<10)

/** Provide a hint to the kernel that the command stream and auxilliary
* state buffers already holds the correct presumed addresses and so the
* relocation process may be skipped if no buffers need to be moved in
* preparation for the execbuffer.
*/
#define I915_EXEC_NO_RELOC (1<<11)

#define __I915_EXEC_UNKNOWN_FLAGS -(I915_EXEC_NO_RELOC<<1)

#define I915_EXEC_CONTEXT_ID_MASK (0xffffffff)
#define i915_execbuffer2_set_context_id(eb2, context) \
(eb2).rsvd1 = context & I915_EXEC_CONTEXT_ID_MASK
Expand Down

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