301 lines
7.0 KiB
C
301 lines
7.0 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2019 Intel Corporation
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*/
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#include "i915_drv.h"
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#include "i915_active.h"
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#define BKL(ref) (&(ref)->i915->drm.struct_mutex)
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/*
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* Active refs memory management
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*
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* To be more economical with memory, we reap all the i915_active trees as
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* they idle (when we know the active requests are inactive) and allocate the
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* nodes from a local slab cache to hopefully reduce the fragmentation.
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*/
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static struct i915_global_active {
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struct kmem_cache *slab_cache;
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} global;
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struct active_node {
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struct i915_active_request base;
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struct i915_active *ref;
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struct rb_node node;
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u64 timeline;
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};
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static void
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__active_park(struct i915_active *ref)
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{
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struct active_node *it, *n;
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rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
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GEM_BUG_ON(i915_active_request_isset(&it->base));
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kmem_cache_free(global.slab_cache, it);
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}
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ref->tree = RB_ROOT;
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}
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static void
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__active_retire(struct i915_active *ref)
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{
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GEM_BUG_ON(!ref->count);
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if (--ref->count)
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return;
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/* return the unused nodes to our slabcache */
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__active_park(ref);
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ref->retire(ref);
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}
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static void
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node_retire(struct i915_active_request *base, struct i915_request *rq)
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{
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__active_retire(container_of(base, struct active_node, base)->ref);
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}
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static void
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last_retire(struct i915_active_request *base, struct i915_request *rq)
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{
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__active_retire(container_of(base, struct i915_active, last));
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}
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static struct i915_active_request *
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active_instance(struct i915_active *ref, u64 idx)
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{
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struct active_node *node;
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struct rb_node **p, *parent;
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struct i915_request *old;
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/*
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* We track the most recently used timeline to skip a rbtree search
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* for the common case, under typical loads we never need the rbtree
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* at all. We can reuse the last slot if it is empty, that is
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* after the previous activity has been retired, or if it matches the
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* current timeline.
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*
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* Note that we allow the timeline to be active simultaneously in
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* the rbtree and the last cache. We do this to avoid having
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* to search and replace the rbtree element for a new timeline, with
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* the cost being that we must be aware that the ref may be retired
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* twice for the same timeline (as the older rbtree element will be
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* retired before the new request added to last).
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*/
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old = i915_active_request_raw(&ref->last, BKL(ref));
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if (!old || old->fence.context == idx)
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goto out;
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/* Move the currently active fence into the rbtree */
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idx = old->fence.context;
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parent = NULL;
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p = &ref->tree.rb_node;
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while (*p) {
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parent = *p;
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node = rb_entry(parent, struct active_node, node);
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if (node->timeline == idx)
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goto replace;
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if (node->timeline < idx)
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p = &parent->rb_right;
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else
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p = &parent->rb_left;
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}
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node = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
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/* kmalloc may retire the ref->last (thanks shrinker)! */
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if (unlikely(!i915_active_request_raw(&ref->last, BKL(ref)))) {
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kmem_cache_free(global.slab_cache, node);
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goto out;
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}
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if (unlikely(!node))
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return ERR_PTR(-ENOMEM);
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i915_active_request_init(&node->base, NULL, node_retire);
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node->ref = ref;
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node->timeline = idx;
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rb_link_node(&node->node, parent, p);
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rb_insert_color(&node->node, &ref->tree);
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replace:
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/*
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* Overwrite the previous active slot in the rbtree with last,
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* leaving last zeroed. If the previous slot is still active,
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* we must be careful as we now only expect to receive one retire
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* callback not two, and so much undo the active counting for the
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* overwritten slot.
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*/
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if (i915_active_request_isset(&node->base)) {
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/* Retire ourselves from the old rq->active_list */
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__list_del_entry(&node->base.link);
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ref->count--;
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GEM_BUG_ON(!ref->count);
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}
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GEM_BUG_ON(list_empty(&ref->last.link));
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list_replace_init(&ref->last.link, &node->base.link);
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node->base.request = fetch_and_zero(&ref->last.request);
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out:
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return &ref->last;
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}
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void i915_active_init(struct drm_i915_private *i915,
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struct i915_active *ref,
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void (*retire)(struct i915_active *ref))
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{
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ref->i915 = i915;
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ref->retire = retire;
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ref->tree = RB_ROOT;
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i915_active_request_init(&ref->last, NULL, last_retire);
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ref->count = 0;
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}
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int i915_active_ref(struct i915_active *ref,
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u64 timeline,
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struct i915_request *rq)
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{
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struct i915_active_request *active;
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int err = 0;
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/* Prevent reaping in case we malloc/wait while building the tree */
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i915_active_acquire(ref);
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active = active_instance(ref, timeline);
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if (IS_ERR(active)) {
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err = PTR_ERR(active);
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goto out;
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}
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if (!i915_active_request_isset(active))
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ref->count++;
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__i915_active_request_set(active, rq);
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GEM_BUG_ON(!ref->count);
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out:
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i915_active_release(ref);
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return err;
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}
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bool i915_active_acquire(struct i915_active *ref)
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{
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lockdep_assert_held(BKL(ref));
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return !ref->count++;
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}
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void i915_active_release(struct i915_active *ref)
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{
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lockdep_assert_held(BKL(ref));
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__active_retire(ref);
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}
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int i915_active_wait(struct i915_active *ref)
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{
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struct active_node *it, *n;
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int ret = 0;
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if (i915_active_acquire(ref))
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goto out_release;
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ret = i915_active_request_retire(&ref->last, BKL(ref));
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if (ret)
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goto out_release;
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rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
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ret = i915_active_request_retire(&it->base, BKL(ref));
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if (ret)
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break;
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}
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out_release:
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i915_active_release(ref);
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return ret;
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}
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int i915_request_await_active_request(struct i915_request *rq,
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struct i915_active_request *active)
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{
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struct i915_request *barrier =
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i915_active_request_raw(active, &rq->i915->drm.struct_mutex);
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return barrier ? i915_request_await_dma_fence(rq, &barrier->fence) : 0;
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}
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int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
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{
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struct active_node *it, *n;
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int err = 0;
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/* await allocates and so we need to avoid hitting the shrinker */
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if (i915_active_acquire(ref))
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goto out; /* was idle */
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err = i915_request_await_active_request(rq, &ref->last);
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if (err)
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goto out;
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rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
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err = i915_request_await_active_request(rq, &it->base);
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if (err)
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goto out;
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}
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out:
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i915_active_release(ref);
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return err;
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}
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#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
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void i915_active_fini(struct i915_active *ref)
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{
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GEM_BUG_ON(i915_active_request_isset(&ref->last));
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GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
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GEM_BUG_ON(ref->count);
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}
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#endif
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int i915_active_request_set(struct i915_active_request *active,
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struct i915_request *rq)
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{
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int err;
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/* Must maintain ordering wrt previous active requests */
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err = i915_request_await_active_request(rq, active);
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if (err)
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return err;
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__i915_active_request_set(active, rq);
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return 0;
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}
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void i915_active_retire_noop(struct i915_active_request *active,
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struct i915_request *request)
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{
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/* Space left intentionally blank */
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}
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#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
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#include "selftests/i915_active.c"
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#endif
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int __init i915_global_active_init(void)
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{
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global.slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
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if (!global.slab_cache)
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return -ENOMEM;
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return 0;
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}
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void __exit i915_global_active_exit(void)
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{
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kmem_cache_destroy(global.slab_cache);
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}
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