a93615f900
Remove the accumulated optimisations that we have for i915_vma_retire and reduce it to the bare essential of tracking the active object reference. This allows us to only use atomic operations, and so will be able to avoid the struct_mutex requirement. The principal loss here is the shrinker MRU bumping, so now if we have to shrink, we will do so in much more random order and more likely to try and shrink recently used objects. That is a nuisance, but shrinking active objects is a second step we try to avoid and will always be a system-wide performance issue. The other loss is here is in the automatic pruning of the reservation_object when idling. This is not as large an issue as upon reservation_object introduction as now adding new fences into the object replaces already signaled fences, keeping the array compact. But we do lose the auto-expiration of stale fences and unused arrays. That may be a noticeable problem for which we need to re-implement autopruning. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190621183801.23252-3-chris@chris-wilson.co.uk
133 lines
3.6 KiB
C
133 lines
3.6 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2014-2018 Intel Corporation
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*/
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#include "i915_gem_batch_pool.h"
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#include "i915_drv.h"
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/**
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* DOC: batch pool
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*
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* In order to submit batch buffers as 'secure', the software command parser
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* must ensure that a batch buffer cannot be modified after parsing. It does
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* this by copying the user provided batch buffer contents to a kernel owned
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* buffer from which the hardware will actually execute, and by carefully
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* managing the address space bindings for such buffers.
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*
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* The batch pool framework provides a mechanism for the driver to manage a
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* set of scratch buffers to use for this purpose. The framework can be
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* extended to support other uses cases should they arise.
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*/
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/**
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* i915_gem_batch_pool_init() - initialize a batch buffer pool
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* @pool: the batch buffer pool
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* @engine: the associated request submission engine
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*/
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void i915_gem_batch_pool_init(struct i915_gem_batch_pool *pool,
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struct intel_engine_cs *engine)
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{
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int n;
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pool->engine = engine;
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for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
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INIT_LIST_HEAD(&pool->cache_list[n]);
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}
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/**
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* i915_gem_batch_pool_fini() - clean up a batch buffer pool
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* @pool: the pool to clean up
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*
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* Note: Callers must hold the struct_mutex.
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*/
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void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
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{
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int n;
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lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
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for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
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struct drm_i915_gem_object *obj, *next;
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list_for_each_entry_safe(obj, next,
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&pool->cache_list[n],
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batch_pool_link)
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i915_gem_object_put(obj);
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INIT_LIST_HEAD(&pool->cache_list[n]);
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}
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}
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/**
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* i915_gem_batch_pool_get() - allocate a buffer from the pool
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* @pool: the batch buffer pool
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* @size: the minimum desired size of the returned buffer
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*
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* Returns an inactive buffer from @pool with at least @size bytes,
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* with the pages pinned. The caller must i915_gem_object_unpin_pages()
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* on the returned object.
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*
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* Note: Callers must hold the struct_mutex
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*
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* Return: the buffer object or an error pointer
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*/
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struct drm_i915_gem_object *
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i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
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size_t size)
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{
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struct drm_i915_gem_object *obj;
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struct list_head *list;
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int n, ret;
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lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
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/* Compute a power-of-two bucket, but throw everything greater than
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* 16KiB into the same bucket: i.e. the the buckets hold objects of
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* (1 page, 2 pages, 4 pages, 8+ pages).
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*/
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n = fls(size >> PAGE_SHIFT) - 1;
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if (n >= ARRAY_SIZE(pool->cache_list))
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n = ARRAY_SIZE(pool->cache_list) - 1;
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list = &pool->cache_list[n];
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list_for_each_entry(obj, list, batch_pool_link) {
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struct reservation_object *resv = obj->base.resv;
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/* The batches are strictly LRU ordered */
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if (!reservation_object_test_signaled_rcu(resv, true))
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break;
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/*
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* The object is now idle, clear the array of shared
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* fences before we add a new request. Although, we
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* remain on the same engine, we may be on a different
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* timeline and so may continually grow the array,
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* trapping a reference to all the old fences, rather
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* than replace the existing fence.
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*/
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if (rcu_access_pointer(resv->fence)) {
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reservation_object_lock(resv, NULL);
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reservation_object_add_excl_fence(resv, NULL);
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reservation_object_unlock(resv);
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}
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if (obj->base.size >= size)
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goto found;
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}
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obj = i915_gem_object_create_internal(pool->engine->i915, size);
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if (IS_ERR(obj))
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return obj;
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found:
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ret = i915_gem_object_pin_pages(obj);
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if (ret)
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return ERR_PTR(ret);
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list_move_tail(&obj->batch_pool_link, list);
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return obj;
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}
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