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/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2018 Intel Corporation
*/
#ifndef _I915_SCHEDULER_H_
#define _I915_SCHEDULER_H_
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <uapi/drm/i915_drm.h>
struct drm_i915_private;
struct i915_request;
struct intel_engine_cs;
enum {
I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1,
I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY,
I915_PRIORITY_MAX = I915_CONTEXT_MAX_USER_PRIORITY + 1,
I915_PRIORITY_INVALID = INT_MIN
};
#define I915_USER_PRIORITY_SHIFT 3
#define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT)
#define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1)
#define I915_PRIORITY_WAIT ((u8)BIT(0))
#define I915_PRIORITY_NEWCLIENT ((u8)BIT(1))
#define I915_PRIORITY_NOSEMAPHORE ((u8)BIT(2))
#define __NO_PREEMPTION (I915_PRIORITY_WAIT)
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.
*/
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_SEMAPHORE BIT(0)
};
struct i915_dependency {
struct i915_sched_node *signaler;
struct list_head signal_link;
struct list_head wait_link;
struct list_head dfs_link;
unsigned long flags;
#define I915_DEPENDENCY_ALLOC BIT(0)
};
struct i915_priolist {
struct list_head requests[I915_PRIORITY_COUNT];
struct rb_node node;
unsigned long used;
int priority;
};
#define priolist_for_each_request(it, plist, idx) \
for (idx = 0; idx < ARRAY_SIZE((plist)->requests); idx++) \
list_for_each_entry(it, &(plist)->requests[idx], sched.link)
#define priolist_for_each_request_consume(it, n, plist, idx) \
for (; \
(plist)->used ? (idx = __ffs((plist)->used)), 1 : 0; \
(plist)->used &= ~BIT(idx)) \
list_for_each_entry_safe(it, n, \
&(plist)->requests[idx], \
sched.link)
void i915_sched_node_init(struct i915_sched_node *node);
bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
struct i915_sched_node *signal,
struct i915_dependency *dep,
unsigned long flags);
int i915_sched_node_add_dependency(struct i915_sched_node *node,
struct i915_sched_node *signal);
void i915_sched_node_fini(struct i915_sched_node *node);
void i915_schedule(struct i915_request *request,
const struct i915_sched_attr *attr);
void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump);
struct list_head *
i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio);
void __i915_priolist_free(struct i915_priolist *p);
static inline void i915_priolist_free(struct i915_priolist *p)
{
if (p->priority != I915_PRIORITY_NORMAL)
__i915_priolist_free(p);
}
#endif /* _I915_SCHEDULER_H_ */
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