From 1233e2db199dea015391db03d3478b3392201c41 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 28 Oct 2016 13:58:37 +0100 Subject: [PATCH] drm/i915: Move object backing storage manipulation to its own locking Break the allocation of the backing storage away from struct_mutex into a per-object lock. This allows parallel page allocation, provided we can do so outside of struct_mutex (i.e. set-domain-ioctl, pwrite, GTT fault), i.e. before execbuf! The increased cost of the atomic counters are hidden behind i915_vma_pin() for the typical case of execbuf, i.e. as the object is typically bound between execbufs, the page_pin_count is static. The cost will be felt around set-domain and pwrite, but offset by the improvement from reduced struct_mutex contention. Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-14-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_drv.h | 36 +++------ drivers/gpu/drm/i915/i915_gem.c | 93 ++++++++++++++++-------- drivers/gpu/drm/i915/i915_gem_shrinker.c | 51 ++++++++----- drivers/gpu/drm/i915/i915_gem_tiling.c | 2 + drivers/gpu/drm/i915/i915_gem_userptr.c | 10 +-- 5 files changed, 114 insertions(+), 78 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index db67bec15ef2..f69e0e03e259 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2274,7 +2274,8 @@ struct drm_i915_gem_object { unsigned int pin_display; struct { - unsigned int pages_pin_count; + struct mutex lock; /* protects the pages and their use */ + atomic_t pages_pin_count; struct sg_table *pages; void *mapping; @@ -2387,13 +2388,6 @@ i915_gem_object_is_dead(const struct drm_i915_gem_object *obj) return atomic_read(&obj->base.refcount.refcount) == 0; } -#if IS_ENABLED(CONFIG_LOCKDEP) -#define lockdep_assert_held_unless(lock, cond) \ - GEM_BUG_ON(debug_locks && !lockdep_is_held(lock) && !(cond)) -#else -#define lockdep_assert_held_unless(lock, cond) -#endif - static inline bool i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj) { @@ -3229,9 +3223,9 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj); static inline int __must_check i915_gem_object_pin_pages(struct drm_i915_gem_object *obj) { - lockdep_assert_held(&obj->base.dev->struct_mutex); + might_lock(&obj->mm.lock); - if (obj->mm.pages_pin_count++) + if (atomic_inc_not_zero(&obj->mm.pages_pin_count)) return 0; return __i915_gem_object_get_pages(obj); @@ -3240,32 +3234,29 @@ i915_gem_object_pin_pages(struct drm_i915_gem_object *obj) static inline void __i915_gem_object_pin_pages(struct drm_i915_gem_object *obj) { - lockdep_assert_held_unless(&obj->base.dev->struct_mutex, - i915_gem_object_is_dead(obj)); GEM_BUG_ON(!obj->mm.pages); - obj->mm.pages_pin_count++; + atomic_inc(&obj->mm.pages_pin_count); } static inline bool i915_gem_object_has_pinned_pages(struct drm_i915_gem_object *obj) { - return obj->mm.pages_pin_count; + return atomic_read(&obj->mm.pages_pin_count); } static inline void __i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj) { - lockdep_assert_held_unless(&obj->base.dev->struct_mutex, - i915_gem_object_is_dead(obj)); GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj)); GEM_BUG_ON(!obj->mm.pages); - obj->mm.pages_pin_count--; - GEM_BUG_ON(obj->mm.pages_pin_count < obj->bind_count); + atomic_dec(&obj->mm.pages_pin_count); + GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count); } -static inline void i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj) +static inline void +i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj) { __i915_gem_object_unpin_pages(obj); } @@ -3288,8 +3279,8 @@ enum i915_map_type { * the kernel address space. Based on the @type of mapping, the PTE will be * set to either WriteBack or WriteCombine (via pgprot_t). * - * The caller must hold the struct_mutex, and is responsible for calling - * i915_gem_object_unpin_map() when the mapping is no longer required. + * The caller is responsible for calling i915_gem_object_unpin_map() when the + * mapping is no longer required. * * Returns the pointer through which to access the mapped object, or an * ERR_PTR() on error. @@ -3305,12 +3296,9 @@ void *__must_check i915_gem_object_pin_map(struct drm_i915_gem_object *obj, * with your access, call i915_gem_object_unpin_map() to release the pin * upon the mapping. Once the pin count reaches zero, that mapping may be * removed. - * - * The caller must hold the struct_mutex. */ static inline void i915_gem_object_unpin_map(struct drm_i915_gem_object *obj) { - lockdep_assert_held(&obj->base.dev->struct_mutex); i915_gem_object_unpin_pages(obj); } diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 56060aeb12e3..c8e9548adfeb 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2269,6 +2269,9 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj) { struct address_space *mapping; + lockdep_assert_held(&obj->mm.lock); + GEM_BUG_ON(obj->mm.pages); + switch (obj->mm.madv) { case I915_MADV_DONTNEED: i915_gem_object_truncate(obj); @@ -2325,12 +2328,17 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj) { struct sg_table *pages; - lockdep_assert_held(&obj->base.dev->struct_mutex); - if (i915_gem_object_has_pinned_pages(obj)) return; GEM_BUG_ON(obj->bind_count); + if (!READ_ONCE(obj->mm.pages)) + return; + + /* May be called by shrinker from within get_pages() (on another bo) */ + mutex_lock_nested(&obj->mm.lock, SINGLE_DEPTH_NESTING); + if (unlikely(atomic_read(&obj->mm.pages_pin_count))) + goto unlock; /* ->put_pages might need to allocate memory for the bit17 swizzle * array, hence protect them from being reaped by removing them from gtt @@ -2353,6 +2361,8 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj) __i915_gem_object_reset_page_iter(obj); obj->ops->put_pages(obj, pages); +unlock: + mutex_unlock(&obj->mm.lock); } static unsigned int swiotlb_max_size(void) @@ -2486,7 +2496,7 @@ err_pages: void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj, struct sg_table *pages) { - lockdep_assert_held(&obj->base.dev->struct_mutex); + lockdep_assert_held(&obj->mm.lock); obj->mm.get_page.sg_pos = pages->sgl; obj->mm.get_page.sg_idx = 0; @@ -2512,9 +2522,9 @@ static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj) } /* Ensure that the associated pages are gathered from the backing storage - * and pinned into our object. i915_gem_object_get_pages() may be called + * and pinned into our object. i915_gem_object_pin_pages() may be called * multiple times before they are released by a single call to - * i915_gem_object_put_pages() - once the pages are no longer referenced + * i915_gem_object_unpin_pages() - once the pages are no longer referenced * either as a result of memory pressure (reaping pages under the shrinker) * or as the object is itself released. */ @@ -2522,15 +2532,23 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj) { int err; - lockdep_assert_held(&obj->base.dev->struct_mutex); + err = mutex_lock_interruptible(&obj->mm.lock); + if (err) + return err; - if (obj->mm.pages) - return 0; + if (likely(obj->mm.pages)) { + __i915_gem_object_pin_pages(obj); + goto unlock; + } + + GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj)); err = ____i915_gem_object_get_pages(obj); - if (err) - __i915_gem_object_unpin_pages(obj); + if (!err) + atomic_set_release(&obj->mm.pages_pin_count, 1); +unlock: + mutex_unlock(&obj->mm.lock); return err; } @@ -2590,20 +2608,29 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, void *ptr; int ret; - lockdep_assert_held(&obj->base.dev->struct_mutex); GEM_BUG_ON(!i915_gem_object_has_struct_page(obj)); - ret = i915_gem_object_pin_pages(obj); + ret = mutex_lock_interruptible(&obj->mm.lock); if (ret) return ERR_PTR(ret); - pinned = obj->mm.pages_pin_count > 1; + pinned = true; + if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) { + ret = ____i915_gem_object_get_pages(obj); + if (ret) + goto err_unlock; + + GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count)); + atomic_set_release(&obj->mm.pages_pin_count, 1); + pinned = false; + } + GEM_BUG_ON(!obj->mm.pages); ptr = ptr_unpack_bits(obj->mm.mapping, has_type); if (ptr && has_type != type) { if (pinned) { ret = -EBUSY; - goto err; + goto err_unpin; } if (is_vmalloc_addr(ptr)) @@ -2618,17 +2645,21 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, ptr = i915_gem_object_map(obj, type); if (!ptr) { ret = -ENOMEM; - goto err; + goto err_unpin; } obj->mm.mapping = ptr_pack_bits(ptr, type); } +out_unlock: + mutex_unlock(&obj->mm.lock); return ptr; -err: - i915_gem_object_unpin_pages(obj); - return ERR_PTR(ret); +err_unpin: + atomic_dec(&obj->mm.pages_pin_count); +err_unlock: + ptr = ERR_PTR(ret); + goto out_unlock; } static void @@ -4268,7 +4299,7 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data, struct drm_i915_private *dev_priv = to_i915(dev); struct drm_i915_gem_madvise *args = data; struct drm_i915_gem_object *obj; - int ret; + int err; switch (args->madv) { case I915_MADV_DONTNEED: @@ -4278,15 +4309,13 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data, return -EINVAL; } - ret = i915_mutex_lock_interruptible(dev); - if (ret) - return ret; - obj = i915_gem_object_lookup(file_priv, args->handle); - if (!obj) { - ret = -ENOENT; - goto unlock; - } + if (!obj) + return -ENOENT; + + err = mutex_lock_interruptible(&obj->mm.lock); + if (err) + goto out; if (obj->mm.pages && i915_gem_object_is_tiled(obj) && @@ -4305,11 +4334,11 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data, i915_gem_object_truncate(obj); args->retained = obj->mm.madv != __I915_MADV_PURGED; + mutex_unlock(&obj->mm.lock); +out: i915_gem_object_put(obj); -unlock: - mutex_unlock(&dev->struct_mutex); - return ret; + return err; } void i915_gem_object_init(struct drm_i915_gem_object *obj, @@ -4317,6 +4346,8 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj, { int i; + mutex_init(&obj->mm.lock); + INIT_LIST_HEAD(&obj->global_list); INIT_LIST_HEAD(&obj->userfault_link); for (i = 0; i < I915_NUM_ENGINES; i++) @@ -4479,7 +4510,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj) obj->ops->release(obj); if (WARN_ON(i915_gem_object_has_pinned_pages(obj))) - obj->mm.pages_pin_count = 0; + atomic_set(&obj->mm.pages_pin_count, 0); if (discard_backing_storage(obj)) obj->mm.madv = I915_MADV_DONTNEED; __i915_gem_object_put_pages(obj); diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c index f95061faeae6..c8a4c40ec2c2 100644 --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c @@ -48,6 +48,20 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task) #endif } +static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock) +{ + if (!mutex_trylock(&dev->struct_mutex)) { + if (!mutex_is_locked_by(&dev->struct_mutex, current)) + return false; + + *unlock = false; + } else { + *unlock = true; + } + + return true; +} + static bool any_vma_pinned(struct drm_i915_gem_object *obj) { struct i915_vma *vma; @@ -66,6 +80,9 @@ static bool swap_available(void) static bool can_release_pages(struct drm_i915_gem_object *obj) { + if (!obj->mm.pages) + return false; + /* Only shmemfs objects are backed by swap */ if (!obj->base.filp) return false; @@ -78,7 +95,7 @@ static bool can_release_pages(struct drm_i915_gem_object *obj) * to the GPU, simply unbinding from the GPU is not going to succeed * in releasing our pin count on the pages themselves. */ - if (obj->mm.pages_pin_count > obj->bind_count) + if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count) return false; if (any_vma_pinned(obj)) @@ -95,7 +112,7 @@ static bool unsafe_drop_pages(struct drm_i915_gem_object *obj) { if (i915_gem_object_unbind(obj) == 0) __i915_gem_object_put_pages(obj); - return !obj->mm.pages; + return !READ_ONCE(obj->mm.pages); } /** @@ -135,6 +152,10 @@ i915_gem_shrink(struct drm_i915_private *dev_priv, { NULL, 0 }, }, *phase; unsigned long count = 0; + bool unlock; + + if (!i915_gem_shrinker_lock(&dev_priv->drm, &unlock)) + return 0; trace_i915_gem_shrink(dev_priv, target, flags); i915_gem_retire_requests(dev_priv); @@ -199,8 +220,14 @@ i915_gem_shrink(struct drm_i915_private *dev_priv, i915_gem_object_get(obj); - if (unsafe_drop_pages(obj)) - count += obj->base.size >> PAGE_SHIFT; + if (unsafe_drop_pages(obj)) { + mutex_lock(&obj->mm.lock); + if (!obj->mm.pages) { + __i915_gem_object_invalidate(obj); + count += obj->base.size >> PAGE_SHIFT; + } + mutex_unlock(&obj->mm.lock); + } i915_gem_object_put(obj); } @@ -211,6 +238,9 @@ i915_gem_shrink(struct drm_i915_private *dev_priv, intel_runtime_pm_put(dev_priv); i915_gem_retire_requests(dev_priv); + if (unlock) + mutex_unlock(&dev_priv->drm.struct_mutex); + /* expedite the RCU grace period to free some request slabs */ synchronize_rcu_expedited(); @@ -244,19 +274,6 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv) return freed; } -static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock) -{ - if (!mutex_trylock(&dev->struct_mutex)) { - if (!mutex_is_locked_by(&dev->struct_mutex, current)) - return false; - - *unlock = false; - } else - *unlock = true; - - return true; -} - static unsigned long i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) { diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c index 34d5ada49720..6608799ee1f9 100644 --- a/drivers/gpu/drm/i915/i915_gem_tiling.c +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c @@ -259,6 +259,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data, if (!err) { struct i915_vma *vma; + mutex_lock(&obj->mm.lock); if (obj->mm.pages && obj->mm.madv == I915_MADV_WILLNEED && dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) { @@ -267,6 +268,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data, if (!i915_gem_object_is_tiled(obj)) __i915_gem_object_pin_pages(obj); } + mutex_unlock(&obj->mm.lock); list_for_each_entry(vma, &obj->vma_list, obj_link) { if (!vma->fence) diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index a421447f1d84..6c8c7b36f7fc 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -79,7 +79,7 @@ static void cancel_userptr(struct work_struct *work) WARN_ONCE(obj->mm.pages, "Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_display=%d\n", obj->bind_count, - obj->mm.pages_pin_count, + atomic_read(&obj->mm.pages_pin_count), obj->pin_display); i915_gem_object_put(obj); @@ -491,7 +491,6 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) { struct get_pages_work *work = container_of(_work, typeof(*work), work); struct drm_i915_gem_object *obj = work->obj; - struct drm_device *dev = obj->base.dev; const int npages = obj->base.size >> PAGE_SHIFT; struct page **pvec; int pinned, ret; @@ -527,7 +526,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) } } - mutex_lock(&dev->struct_mutex); + mutex_lock(&obj->mm.lock); if (obj->userptr.work == &work->work) { struct sg_table *pages = ERR_PTR(ret); @@ -542,13 +541,12 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) obj->userptr.work = ERR_CAST(pages); } - - i915_gem_object_put(obj); - mutex_unlock(&dev->struct_mutex); + mutex_unlock(&obj->mm.lock); release_pages(pvec, pinned, 0); drm_free_large(pvec); + i915_gem_object_put_unlocked(obj); put_task_struct(work->task); kfree(work); } -- 2.39.5