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path: root/drivers/gpu/drm/i915/i915_scheduler.c
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Diffstat (limited to 'drivers/gpu/drm/i915/i915_scheduler.c')
-rw-r--r--drivers/gpu/drm/i915/i915_scheduler.c399
1 files changed, 399 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
new file mode 100644
index 000000000000..340faea6c08a
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -0,0 +1,399 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2018 Intel Corporation
+ */
+
+#include <linux/mutex.h>
+
+#include "i915_drv.h"
+#include "i915_request.h"
+#include "i915_scheduler.h"
+
+static DEFINE_SPINLOCK(schedule_lock);
+
+static const struct i915_request *
+node_to_request(const struct i915_sched_node *node)
+{
+ return container_of(node, const struct i915_request, sched);
+}
+
+static inline bool node_signaled(const struct i915_sched_node *node)
+{
+ return i915_request_completed(node_to_request(node));
+}
+
+void i915_sched_node_init(struct i915_sched_node *node)
+{
+ INIT_LIST_HEAD(&node->signalers_list);
+ INIT_LIST_HEAD(&node->waiters_list);
+ INIT_LIST_HEAD(&node->link);
+ node->attr.priority = I915_PRIORITY_INVALID;
+}
+
+static struct i915_dependency *
+i915_dependency_alloc(struct drm_i915_private *i915)
+{
+ return kmem_cache_alloc(i915->dependencies, GFP_KERNEL);
+}
+
+static void
+i915_dependency_free(struct drm_i915_private *i915,
+ struct i915_dependency *dep)
+{
+ kmem_cache_free(i915->dependencies, dep);
+}
+
+bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
+ struct i915_sched_node *signal,
+ struct i915_dependency *dep,
+ unsigned long flags)
+{
+ bool ret = false;
+
+ spin_lock(&schedule_lock);
+
+ if (!node_signaled(signal)) {
+ INIT_LIST_HEAD(&dep->dfs_link);
+ list_add(&dep->wait_link, &signal->waiters_list);
+ list_add(&dep->signal_link, &node->signalers_list);
+ dep->signaler = signal;
+ dep->flags = flags;
+
+ ret = true;
+ }
+
+ spin_unlock(&schedule_lock);
+
+ return ret;
+}
+
+int i915_sched_node_add_dependency(struct drm_i915_private *i915,
+ struct i915_sched_node *node,
+ struct i915_sched_node *signal)
+{
+ struct i915_dependency *dep;
+
+ dep = i915_dependency_alloc(i915);
+ if (!dep)
+ return -ENOMEM;
+
+ if (!__i915_sched_node_add_dependency(node, signal, dep,
+ I915_DEPENDENCY_ALLOC))
+ i915_dependency_free(i915, dep);
+
+ return 0;
+}
+
+void i915_sched_node_fini(struct drm_i915_private *i915,
+ struct i915_sched_node *node)
+{
+ struct i915_dependency *dep, *tmp;
+
+ GEM_BUG_ON(!list_empty(&node->link));
+
+ spin_lock(&schedule_lock);
+
+ /*
+ * Everyone we depended upon (the fences we wait to be signaled)
+ * should retire before us and remove themselves from our list.
+ * However, retirement is run independently on each timeline and
+ * so we may be called out-of-order.
+ */
+ list_for_each_entry_safe(dep, tmp, &node->signalers_list, signal_link) {
+ GEM_BUG_ON(!node_signaled(dep->signaler));
+ GEM_BUG_ON(!list_empty(&dep->dfs_link));
+
+ list_del(&dep->wait_link);
+ if (dep->flags & I915_DEPENDENCY_ALLOC)
+ i915_dependency_free(i915, dep);
+ }
+
+ /* Remove ourselves from everyone who depends upon us */
+ list_for_each_entry_safe(dep, tmp, &node->waiters_list, wait_link) {
+ GEM_BUG_ON(dep->signaler != node);
+ GEM_BUG_ON(!list_empty(&dep->dfs_link));
+
+ list_del(&dep->signal_link);
+ if (dep->flags & I915_DEPENDENCY_ALLOC)
+ i915_dependency_free(i915, dep);
+ }
+
+ spin_unlock(&schedule_lock);
+}
+
+static inline struct i915_priolist *to_priolist(struct rb_node *rb)
+{
+ return rb_entry(rb, struct i915_priolist, node);
+}
+
+static void assert_priolists(struct intel_engine_execlists * const execlists,
+ long queue_priority)
+{
+ struct rb_node *rb;
+ long last_prio, i;
+
+ if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
+ return;
+
+ GEM_BUG_ON(rb_first_cached(&execlists->queue) !=
+ rb_first(&execlists->queue.rb_root));
+
+ last_prio = (queue_priority >> I915_USER_PRIORITY_SHIFT) + 1;
+ for (rb = rb_first_cached(&execlists->queue); rb; rb = rb_next(rb)) {
+ const struct i915_priolist *p = to_priolist(rb);
+
+ GEM_BUG_ON(p->priority >= last_prio);
+ last_prio = p->priority;
+
+ GEM_BUG_ON(!p->used);
+ for (i = 0; i < ARRAY_SIZE(p->requests); i++) {
+ if (list_empty(&p->requests[i]))
+ continue;
+
+ GEM_BUG_ON(!(p->used & BIT(i)));
+ }
+ }
+}
+
+struct list_head *
+i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio)
+{
+ struct intel_engine_execlists * const execlists = &engine->execlists;
+ struct i915_priolist *p;
+ struct rb_node **parent, *rb;
+ bool first = true;
+ int idx, i;
+
+ lockdep_assert_held(&engine->timeline.lock);
+ assert_priolists(execlists, INT_MAX);
+
+ /* buckets sorted from highest [in slot 0] to lowest priority */
+ idx = I915_PRIORITY_COUNT - (prio & I915_PRIORITY_MASK) - 1;
+ prio >>= I915_USER_PRIORITY_SHIFT;
+ if (unlikely(execlists->no_priolist))
+ prio = I915_PRIORITY_NORMAL;
+
+find_priolist:
+ /* most positive priority is scheduled first, equal priorities fifo */
+ rb = NULL;
+ parent = &execlists->queue.rb_root.rb_node;
+ while (*parent) {
+ rb = *parent;
+ p = to_priolist(rb);
+ if (prio > p->priority) {
+ parent = &rb->rb_left;
+ } else if (prio < p->priority) {
+ parent = &rb->rb_right;
+ first = false;
+ } else {
+ goto out;
+ }
+ }
+
+ if (prio == I915_PRIORITY_NORMAL) {
+ p = &execlists->default_priolist;
+ } else {
+ p = kmem_cache_alloc(engine->i915->priorities, GFP_ATOMIC);
+ /* Convert an allocation failure to a priority bump */
+ if (unlikely(!p)) {
+ prio = I915_PRIORITY_NORMAL; /* recurses just once */
+
+ /* To maintain ordering with all rendering, after an
+ * allocation failure we have to disable all scheduling.
+ * Requests will then be executed in fifo, and schedule
+ * will ensure that dependencies are emitted in fifo.
+ * There will be still some reordering with existing
+ * requests, so if userspace lied about their
+ * dependencies that reordering may be visible.
+ */
+ execlists->no_priolist = true;
+ goto find_priolist;
+ }
+ }
+
+ p->priority = prio;
+ for (i = 0; i < ARRAY_SIZE(p->requests); i++)
+ INIT_LIST_HEAD(&p->requests[i]);
+ rb_link_node(&p->node, rb, parent);
+ rb_insert_color_cached(&p->node, &execlists->queue, first);
+ p->used = 0;
+
+out:
+ p->used |= BIT(idx);
+ return &p->requests[idx];
+}
+
+static struct intel_engine_cs *
+sched_lock_engine(struct i915_sched_node *node, struct intel_engine_cs *locked)
+{
+ struct intel_engine_cs *engine = node_to_request(node)->engine;
+
+ GEM_BUG_ON(!locked);
+
+ if (engine != locked) {
+ spin_unlock(&locked->timeline.lock);
+ spin_lock(&engine->timeline.lock);
+ }
+
+ return engine;
+}
+
+static void __i915_schedule(struct i915_request *rq,
+ const struct i915_sched_attr *attr)
+{
+ struct list_head *uninitialized_var(pl);
+ struct intel_engine_cs *engine, *last;
+ struct i915_dependency *dep, *p;
+ struct i915_dependency stack;
+ const int prio = attr->priority;
+ LIST_HEAD(dfs);
+
+ /* Needed in order to use the temporary link inside i915_dependency */
+ lockdep_assert_held(&schedule_lock);
+ GEM_BUG_ON(prio == I915_PRIORITY_INVALID);
+
+ if (i915_request_completed(rq))
+ return;
+
+ if (prio <= READ_ONCE(rq->sched.attr.priority))
+ return;
+
+ stack.signaler = &rq->sched;
+ list_add(&stack.dfs_link, &dfs);
+
+ /*
+ * Recursively bump all dependent priorities to match the new request.
+ *
+ * A naive approach would be to use recursion:
+ * static void update_priorities(struct i915_sched_node *node, prio) {
+ * list_for_each_entry(dep, &node->signalers_list, signal_link)
+ * update_priorities(dep->signal, prio)
+ * queue_request(node);
+ * }
+ * but that may have unlimited recursion depth and so runs a very
+ * real risk of overunning the kernel stack. Instead, we build
+ * a flat list of all dependencies starting with the current request.
+ * As we walk the list of dependencies, we add all of its dependencies
+ * to the end of the list (this may include an already visited
+ * request) and continue to walk onwards onto the new dependencies. The
+ * end result is a topological list of requests in reverse order, the
+ * last element in the list is the request we must execute first.
+ */
+ list_for_each_entry(dep, &dfs, dfs_link) {
+ struct i915_sched_node *node = dep->signaler;
+
+ /*
+ * Within an engine, there can be no cycle, but we may
+ * refer to the same dependency chain multiple times
+ * (redundant dependencies are not eliminated) and across
+ * engines.
+ */
+ list_for_each_entry(p, &node->signalers_list, signal_link) {
+ GEM_BUG_ON(p == dep); /* no cycles! */
+
+ if (node_signaled(p->signaler))
+ continue;
+
+ GEM_BUG_ON(p->signaler->attr.priority < node->attr.priority);
+ if (prio > READ_ONCE(p->signaler->attr.priority))
+ list_move_tail(&p->dfs_link, &dfs);
+ }
+ }
+
+ /*
+ * If we didn't need to bump any existing priorities, and we haven't
+ * yet submitted this request (i.e. there is no potential race with
+ * execlists_submit_request()), we can set our own priority and skip
+ * acquiring the engine locks.
+ */
+ if (rq->sched.attr.priority == I915_PRIORITY_INVALID) {
+ GEM_BUG_ON(!list_empty(&rq->sched.link));
+ rq->sched.attr = *attr;
+
+ if (stack.dfs_link.next == stack.dfs_link.prev)
+ return;
+
+ __list_del_entry(&stack.dfs_link);
+ }
+
+ last = NULL;
+ engine = rq->engine;
+ spin_lock_irq(&engine->timeline.lock);
+
+ /* Fifo and depth-first replacement ensure our deps execute before us */
+ list_for_each_entry_safe_reverse(dep, p, &dfs, dfs_link) {
+ struct i915_sched_node *node = dep->signaler;
+
+ INIT_LIST_HEAD(&dep->dfs_link);
+
+ engine = sched_lock_engine(node, engine);
+
+ /* Recheck after acquiring the engine->timeline.lock */
+ if (prio <= node->attr.priority || node_signaled(node))
+ continue;
+
+ node->attr.priority = prio;
+ if (!list_empty(&node->link)) {
+ if (last != engine) {
+ pl = i915_sched_lookup_priolist(engine, prio);
+ last = engine;
+ }
+ list_move_tail(&node->link, pl);
+ } else {
+ /*
+ * If the request is not in the priolist queue because
+ * it is not yet runnable, then it doesn't contribute
+ * to our preemption decisions. On the other hand,
+ * if the request is on the HW, it too is not in the
+ * queue; but in that case we may still need to reorder
+ * the inflight requests.
+ */
+ if (!i915_sw_fence_done(&node_to_request(node)->submit))
+ continue;
+ }
+
+ if (prio <= engine->execlists.queue_priority)
+ continue;
+
+ /*
+ * If we are already the currently executing context, don't
+ * bother evaluating if we should preempt ourselves.
+ */
+ if (node_to_request(node)->global_seqno &&
+ i915_seqno_passed(port_request(engine->execlists.port)->global_seqno,
+ node_to_request(node)->global_seqno))
+ continue;
+
+ /* Defer (tasklet) submission until after all of our updates. */
+ engine->execlists.queue_priority = prio;
+ tasklet_hi_schedule(&engine->execlists.tasklet);
+ }
+
+ spin_unlock_irq(&engine->timeline.lock);
+}
+
+void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr)
+{
+ spin_lock(&schedule_lock);
+ __i915_schedule(rq, attr);
+ spin_unlock(&schedule_lock);
+}
+
+void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump)
+{
+ struct i915_sched_attr attr;
+
+ GEM_BUG_ON(bump & ~I915_PRIORITY_MASK);
+
+ if (READ_ONCE(rq->sched.attr.priority) == I915_PRIORITY_INVALID)
+ return;
+
+ spin_lock_bh(&schedule_lock);
+
+ attr = rq->sched.attr;
+ attr.priority |= bump;
+ __i915_schedule(rq, &attr);
+
+ spin_unlock_bh(&schedule_lock);
+}