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drm/i915: add some kernel-doc for shrink_pin and friends

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Attempt to document shrink_pin and the other relevant interfaces that
interact with it, before we start messing with it.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018091055.1998191-5-matthew.auld@intel.com
This commit is contained in:
Matthew Auld
2021-10-18 10:10:52 +01:00
parent 893f11f0c7
commit e25d1ea4b1
2 changed files with 54 additions and 1 deletions
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24
drivers/gpu/drm/i915/gem/i915_gem_object_types.h
View File

@@ -488,6 +488,28 @@ struct drm_i915_gem_object {
* instead go through the pin/unpin interfaces.
*/
atomic_t pages_pin_count;
/**
* @shrink_pin: Prevents the pages from being made visible to
* the shrinker, while the shrink_pin is non-zero. Most users
* should pretty much never have to care about this, outside of
* some special use cases.
*
* By default most objects will start out as visible to the
* shrinker(if I915_GEM_OBJECT_IS_SHRINKABLE) as soon as the
* backing pages are attached to the object, like in
* __i915_gem_object_set_pages(). They will then be removed the
* shrinker list once the pages are released.
*
* The @shrink_pin is incremented by calling
* i915_gem_object_make_unshrinkable(), which will also remove
* the object from the shrinker list, if the pin count was zero.
*
* Callers will then typically call
* i915_gem_object_make_shrinkable() or
* i915_gem_object_make_purgeable() to decrement the pin count,
* and make the pages visible again.
*/
atomic_t shrink_pin;
/**
@@ -549,7 +571,7 @@ struct drm_i915_gem_object {
struct i915_gem_object_page_iter get_dma_page;
/**
* Element within i915->mm.unbound_list or i915->mm.bound_list,
* Element within i915->mm.shrink_list or i915->mm.purge_list,
* locked by i915->mm.obj_lock.
*/
struct list_head link;

31
drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
View File

@@ -463,6 +463,16 @@ void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
#define obj_to_i915(obj__) to_i915((obj__)->base.dev)
/**
* i915_gem_object_make_unshrinkable - Hide the object from the shrinker. By
* default all object types that support shrinking(see IS_SHRINKABLE), will also
* make the object visible to the shrinker after allocating the system memory
* pages.
* @obj: The GEM object.
*
* This is typically used for special kernel internal objects that can't be
* easily processed by the shrinker, like if they are perma-pinned.
*/
void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj)
{
struct drm_i915_private *i915 = obj_to_i915(obj);
@@ -513,12 +523,33 @@ static void __i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj,
spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
}
/**
* i915_gem_object_make_shrinkable - Move the object to the tail of the
* shrinkable list. Objects on this list might be swapped out. Used with
* WILLNEED objects.
* @obj: The GEM object.
*
* MUST only be called on objects which have backing pages.
*
* MUST be balanced with previous call to i915_gem_object_make_unshrinkable().
*/
void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj)
{
__i915_gem_object_make_shrinkable(obj,
&obj_to_i915(obj)->mm.shrink_list);
}
/**
* i915_gem_object_make_purgeable - Move the object to the tail of the purgeable
* list. Used with DONTNEED objects. Unlike with shrinkable objects, the
* shrinker will attempt to discard the backing pages, instead of trying to swap
* them out.
* @obj: The GEM object.
*
* MUST only be called on objects which have backing pages.
*
* MUST be balanced with previous call to i915_gem_object_make_unshrinkable().
*/
void i915_gem_object_make_purgeable(struct drm_i915_gem_object *obj)
{
__i915_gem_object_make_shrinkable(obj,