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 <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-14-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index a421447..6c8c7b3 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);
}