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/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2018 Intel Corporation
*/
#ifndef _I915_SCHEDULER_H_
#define _I915_SCHEDULER_H_
#include <linux/bitops.h>
#include <uapi/drm/i915_drm.h>
enum {
I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1,
I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY,
I915_PRIORITY_MAX = I915_CONTEXT_MAX_USER_PRIORITY + 1,
I915_PRIORITY_INVALID = INT_MIN
};
#define I915_USER_PRIORITY_SHIFT 0
#define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1)
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.
*/
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;
};
struct i915_dependency {
struct i915_sched_node *signaler;
struct list_head signal_link;
struct list_head wait_link;
struct list_head dfs_link;
unsigned long flags;
#define I915_DEPENDENCY_ALLOC BIT(0)
};
#endif /* _I915_SCHEDULER_H_ */
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