drivers/gpu/drm/i915/i915_scheduler_types.h

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/i915/i915_scheduler_types.h

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/i915/i915_scheduler_types.h
Extension
.h
Size
6244 bytes
Lines
206
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct i915_sched_attr {
	/**
	 * @priority: execution and service priority
	 *
	 * All clients are equal, but some are more equal than others!
	 *
	 * Requests from a context with a greater (more positive) value of
	 * @priority will be executed before those with a lower @priority
	 * value, forming a simple QoS.
	 *
	 * The &drm_i915_private.kernel_context is assigned the lowest priority.
	 */
	int priority;
};

/*
 * "People assume that time is a strict progression of cause to effect, but
 * actually, from a nonlinear, non-subjective viewpoint, it's more like a big
 * ball of wibbly-wobbly, timey-wimey ... stuff." -The Doctor, 2015
 *
 * Requests exist in a complex web of interdependencies. Each request
 * has to wait for some other request to complete before it is ready to be run
 * (e.g. we have to wait until the pixels have been rendering into a texture
 * before we can copy from it). We track the readiness of a request in terms
 * of fences, but we also need to keep the dependency tree for the lifetime
 * of the request (beyond the life of an individual fence). We use the tree
 * at various points to reorder the requests whilst keeping the requests
 * in order with respect to their various dependencies.
 *
 * There is no active component to the "scheduler". As we know the dependency
 * DAG of each request, we are able to insert it into a sorted queue when it
 * is ready, and are able to reorder its portion of the graph to accommodate
 * dynamic priority changes.
 *
 * Ok, there is now one active element to the "scheduler" in the backends.
 * We let a new context run for a small amount of time before re-evaluating
 * the run order. As we re-evaluate, we maintain the strict ordering of
 * dependencies, but attempt to rotate the active contexts (the current context
 * is put to the back of its priority queue, then reshuffling its dependents).
 * This provides minimal timeslicing and prevents a userspace hog (e.g.
 * something waiting on a user semaphore [VkEvent]) from denying service to
 * others.
 */
struct i915_sched_node {
	struct list_head signalers_list; /* those before us, we depend upon */
	struct list_head waiters_list; /* those after us, they depend upon us */
	struct list_head link;
	struct i915_sched_attr attr;
	unsigned int flags;
#define I915_SCHED_HAS_EXTERNAL_CHAIN	BIT(0)
	intel_engine_mask_t semaphores;
};

struct i915_dependency {
	struct i915_sched_node *signaler;
	struct i915_sched_node *waiter;
	struct list_head signal_link;
	struct list_head wait_link;
	struct list_head dfs_link;
	unsigned long flags;
#define I915_DEPENDENCY_ALLOC		BIT(0)
#define I915_DEPENDENCY_EXTERNAL	BIT(1)
#define I915_DEPENDENCY_WEAK		BIT(2)
};

#define for_each_waiter(p__, rq__) \
	list_for_each_entry_lockless(p__, \
				     &(rq__)->sched.waiters_list, \
				     wait_link)

#define for_each_signaler(p__, rq__) \
	list_for_each_entry_rcu(p__, \
				&(rq__)->sched.signalers_list, \
				signal_link)

/**
 * struct i915_sched_engine - scheduler engine
 *
 * A schedule engine represents a submission queue with different priority
 * bands. It contains all the common state (relative to the backend) to queue,
 * track, and submit a request.
 *
 * This object at the moment is quite i915 specific but will transition into a
 * container for the drm_gpu_scheduler plus a few other variables once the i915
 * is integrated with the DRM scheduler.
 */
struct i915_sched_engine {
	/**
	 * @ref: reference count of schedule engine object
	 */

Annotation

Implementation Notes