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 #include <linux/kernel.h> 12 13 #include <uapi/drm/i915_drm.h> 14 15 struct drm_i915_private; 16 struct i915_request; 17 struct intel_engine_cs; 18 19 enum { 20 I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1, 21 I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY, 22 I915_PRIORITY_MAX = I915_CONTEXT_MAX_USER_PRIORITY + 1, 23 24 I915_PRIORITY_INVALID = INT_MIN 25 }; 26 27 #define I915_USER_PRIORITY_SHIFT 1 28 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT) 29 30 #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT) 31 #define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1) 32 33 #define I915_PRIORITY_NEWCLIENT ((u8)BIT(0)) 34 35 struct i915_sched_attr { 36 /** 37 * @priority: execution and service priority 38 * 39 * All clients are equal, but some are more equal than others! 40 * 41 * Requests from a context with a greater (more positive) value of 42 * @priority will be executed before those with a lower @priority 43 * value, forming a simple QoS. 44 * 45 * The &drm_i915_private.kernel_context is assigned the lowest priority. 46 */ 47 int priority; 48 }; 49 50 /* 51 * "People assume that time is a strict progression of cause to effect, but 52 * actually, from a nonlinear, non-subjective viewpoint, it's more like a big 53 * ball of wibbly-wobbly, timey-wimey ... stuff." -The Doctor, 2015 54 * 55 * Requests exist in a complex web of interdependencies. Each request 56 * has to wait for some other request to complete before it is ready to be run 57 * (e.g. we have to wait until the pixels have been rendering into a texture 58 * before we can copy from it). We track the readiness of a request in terms 59 * of fences, but we also need to keep the dependency tree for the lifetime 60 * of the request (beyond the life of an individual fence). We use the tree 61 * at various points to reorder the requests whilst keeping the requests 62 * in order with respect to their various dependencies. 63 * 64 * There is no active component to the "scheduler". As we know the dependency 65 * DAG of each request, we are able to insert it into a sorted queue when it 66 * is ready, and are able to reorder its portion of the graph to accommodate 67 * dynamic priority changes. 68 */ 69 struct i915_sched_node { 70 struct list_head signalers_list; /* those before us, we depend upon */ 71 struct list_head waiters_list; /* those after us, they depend upon us */ 72 struct list_head link; 73 struct i915_sched_attr attr; 74 }; 75 76 struct i915_dependency { 77 struct i915_sched_node *signaler; 78 struct list_head signal_link; 79 struct list_head wait_link; 80 struct list_head dfs_link; 81 unsigned long flags; 82 #define I915_DEPENDENCY_ALLOC BIT(0) 83 }; 84 85 void i915_sched_node_init(struct i915_sched_node *node); 86 87 bool __i915_sched_node_add_dependency(struct i915_sched_node *node, 88 struct i915_sched_node *signal, 89 struct i915_dependency *dep, 90 unsigned long flags); 91 92 int i915_sched_node_add_dependency(struct drm_i915_private *i915, 93 struct i915_sched_node *node, 94 struct i915_sched_node *signal); 95 96 void i915_sched_node_fini(struct drm_i915_private *i915, 97 struct i915_sched_node *node); 98 99 void i915_schedule(struct i915_request *request, 100 const struct i915_sched_attr *attr); 101 102 struct list_head * 103 i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio); 104 105 #endif /* _I915_SCHEDULER_H_ */ 106