| /* |
| * SPDX-License-Identifier: MIT |
| * |
| * Copyright © 2018 Intel Corporation |
| */ |
| |
| #ifndef _I915_SCHEDULER_TYPES_H_ |
| #define _I915_SCHEDULER_TYPES_H_ |
| |
| #include <linux/list.h> |
| |
| #include "gt/intel_engine_types.h" |
| #include "i915_priolist_types.h" |
| |
| struct drm_i915_private; |
| struct i915_request; |
| struct intel_engine_cs; |
| |
| 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. |
| * |
| * Ok, there is now one active element to the "scheduler" in the backends. |
| * We let a new context run for a small amount of time before re-evaluating |
| * the run order. As we re-evaluate, we maintain the strict ordering of |
| * dependencies, but attempt to rotate the active contexts (the current context |
| * is put to the back of its priority queue, then reshuffling its dependents). |
| * This provides minimal timeslicing and prevents a userspace hog (e.g. |
| * something waiting on a user semaphore [VkEvent]) from denying service to |
| * others. |
| */ |
| 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; |
| unsigned int flags; |
| #define I915_SCHED_HAS_EXTERNAL_CHAIN BIT(0) |
| intel_engine_mask_t semaphores; |
| }; |
| |
| struct i915_dependency { |
| struct i915_sched_node *signaler; |
| struct i915_sched_node *waiter; |
| struct list_head signal_link; |
| struct list_head wait_link; |
| struct list_head dfs_link; |
| unsigned long flags; |
| #define I915_DEPENDENCY_ALLOC BIT(0) |
| #define I915_DEPENDENCY_EXTERNAL BIT(1) |
| #define I915_DEPENDENCY_WEAK BIT(2) |
| }; |
| |
| #define for_each_waiter(p__, rq__) \ |
| list_for_each_entry_lockless(p__, \ |
| &(rq__)->sched.waiters_list, \ |
| wait_link) |
| |
| #define for_each_signaler(p__, rq__) \ |
| list_for_each_entry_rcu(p__, \ |
| &(rq__)->sched.signalers_list, \ |
| signal_link) |
| |
| #endif /* _I915_SCHEDULER_TYPES_H_ */ |