drivers/gpu/drm/i915/i915_scheduler.h

   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_ */