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 #define I915_USER_PRIORITY_SHIFT 0 23 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT) 24 25 #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT) 26 #define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1) 27 28 struct i915_sched_attr { 29 /** 30 * @priority: execution and service priority 31 * 32 * All clients are equal, but some are more equal than others! 33 * 34 * Requests from a context with a greater (more positive) value of 35 * @priority will be executed before those with a lower @priority 36 * value, forming a simple QoS. 37 * 38 * The &drm_i915_private.kernel_context is assigned the lowest priority. 39 */ 40 int priority; 41 }; 42 43 /* 44 * "People assume that time is a strict progression of cause to effect, but 45 * actually, from a nonlinear, non-subjective viewpoint, it's more like a big 46 * ball of wibbly-wobbly, timey-wimey ... stuff." -The Doctor, 2015 47 * 48 * Requests exist in a complex web of interdependencies. Each request 49 * has to wait for some other request to complete before it is ready to be run 50 * (e.g. we have to wait until the pixels have been rendering into a texture 51 * before we can copy from it). We track the readiness of a request in terms 52 * of fences, but we also need to keep the dependency tree for the lifetime 53 * of the request (beyond the life of an individual fence). We use the tree 54 * at various points to reorder the requests whilst keeping the requests 55 * in order with respect to their various dependencies. 56 * 57 * There is no active component to the "scheduler". As we know the dependency 58 * DAG of each request, we are able to insert it into a sorted queue when it 59 * is ready, and are able to reorder its portion of the graph to accommodate 60 * dynamic priority changes. 61 */ 62 struct i915_sched_node { 63 struct list_head signalers_list; /* those before us, we depend upon */ 64 struct list_head waiters_list; /* those after us, they depend upon us */ 65 struct list_head link; 66 struct i915_sched_attr attr; 67 }; 68 69 struct i915_dependency { 70 struct i915_sched_node *signaler; 71 struct list_head signal_link; 72 struct list_head wait_link; 73 struct list_head dfs_link; 74 unsigned long flags; 75 #define I915_DEPENDENCY_ALLOC BIT(0) 76 }; 77 78 #endif /* _I915_SCHEDULER_H_ */ 79