From 3d574a6bbb12a6c3bbeea807a1724b44a0f6ebbb Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 13 Oct 2017 21:26:16 +0100 Subject: drm/i915: Remove walk over obj->vma_list for the shrinker In the next patch, we want to reduce the lock coverage within the shrinker, and one of the dangerous walks we have is over obj->vma_list. We are only walking the obj->vma_list in order to check whether it has been permanently pinned by HW access, typically via use on the scanout. But we have a couple of other long term pins, the context objects for which we currently have to check the individual vma pin_count. If we instead mark these using obj->pin_display, we can forgo the dangerous and sometimes slow list iteration. v2: Rearrange code to try and avoid confusion from false associations due to arrangement of whitespace along with rebasing on obj->pin_global. Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20171013202621.7276-4-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_shrinker.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-) (limited to 'drivers/gpu/drm/i915/i915_gem_shrinker.c') diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c index b5c87d89777b..575a6b735f39 100644 --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c @@ -71,25 +71,6 @@ static void shrinker_unlock(struct drm_i915_private *dev_priv, bool unlock) mutex_unlock(&dev_priv->drm.struct_mutex); } -static bool any_vma_pinned(struct drm_i915_gem_object *obj) -{ - struct i915_vma *vma; - - list_for_each_entry(vma, &obj->vma_list, obj_link) { - /* Only GGTT vma may be permanently pinned, and are always - * at the start of the list. We can stop hunting as soon - * as we see a ppGTT vma. - */ - if (!i915_vma_is_ggtt(vma)) - break; - - if (i915_vma_is_pinned(vma)) - return true; - } - - return false; -} - static bool swap_available(void) { return get_nr_swap_pages() > 0; @@ -115,7 +96,13 @@ static bool can_release_pages(struct drm_i915_gem_object *obj) if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count) return false; - if (any_vma_pinned(obj)) + /* If any vma are "permanently" pinned, it will prevent us from + * reclaiming the obj->mm.pages. We only allow scanout objects to claim + * a permanent pin, along with a few others like the context objects. + * To simplify the scan, and to avoid walking the list of vma under the + * object, we just check the count of its permanently pinned. + */ + if (obj->pin_global) return false; /* We can only return physical pages to the system if we can either -- cgit v1.2.3