i915_scheduler_types.h | Explore in Territory

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2018 Intel Corporation
 */

#ifndef _I915_SCHEDULER_TYPES_H_
#define _I915_SCHEDULER_TYPES_H_

#include <linux/list.h>

#include "gt/intel_engine_types.h"
#include "i915_priolist_types.h"

struct drm_i915_private;
struct i915_request;
struct intel_engine_cs;

struct i915_sched_attr { … };

/*
 * "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 i915_dependency { … };

#define for_each_waiter(p__, rq__) …

#define for_each_signaler(p__, rq__) …

/**
 * 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 { … };

#endif /* _I915_SCHEDULER_TYPES_H_ */
linux/drivers/gpu/drm/i915/i915_scheduler_types.h
