1 /* 2 * SPDX-License-Identifier: MIT 3 * 4 * Copyright © 2018 Intel Corporation 5 */ 6 7 #ifndef _I915_SCHEDULER_H_ 8 #define _I915_SCHEDULER_H_ 9 10 #include <linux/bitops.h> 11 12 #include <uapi/drm/i915_drm.h> 13 14 enum { 15 I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1, 16 I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY, 17 I915_PRIORITY_MAX = I915_CONTEXT_MAX_USER_PRIORITY + 1, 18 19 I915_PRIORITY_INVALID = INT_MIN 20 }; 21 22 /* 23 * "People assume that time is a strict progression of cause to effect, but 24 * actually, from a nonlinear, non-subjective viewpoint, it's more like a big 25 * ball of wibbly-wobbly, timey-wimey ... stuff." -The Doctor, 2015 26 * 27 * Requests exist in a complex web of interdependencies. Each request 28 * has to wait for some other request to complete before it is ready to be run 29 * (e.g. we have to wait until the pixels have been rendering into a texture 30 * before we can copy from it). We track the readiness of a request in terms 31 * of fences, but we also need to keep the dependency tree for the lifetime 32 * of the request (beyond the life of an individual fence). We use the tree 33 * at various points to reorder the requests whilst keeping the requests 34 * in order with respect to their various dependencies. 35 * 36 * There is no active component to the "scheduler". As we know the dependency 37 * DAG of each request, we are able to insert it into a sorted queue when it 38 * is ready, and are able to reorder its portion of the graph to accommodate 39 * dynamic priority changes. 40 */ 41 struct i915_sched_node { 42 struct list_head signalers_list; /* those before us, we depend upon */ 43 struct list_head waiters_list; /* those after us, they depend upon us */ 44 struct list_head link; 45 int priority; 46 }; 47 48 struct i915_dependency { 49 struct i915_sched_node *signaler; 50 struct list_head signal_link; 51 struct list_head wait_link; 52 struct list_head dfs_link; 53 unsigned long flags; 54 #define I915_DEPENDENCY_ALLOC BIT(0) 55 }; 56 57 #endif /* _I915_SCHEDULER_H_ */ 58