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