[Intel-gfx] [PATCH 3/4] drm/i915: Add support for stealing purgable stolen pages
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Tue Sep 15 08:14:49 PDT 2015
On 09/15/2015 09:33 AM, ankitprasad.r.sharma at intel.com wrote:
> From: Chris Wilson <chris at chris-wilson.co.uk>
>
> If we run out of stolen memory when trying to allocate an object, see if
> we can reap enough purgeable objects to free up enough contiguous free
> space for the allocation. This is in principle very much like evicting
> objects to free up enough contiguous space in the vma when binding
> a new object - and you will be forgiven for thinking that the code looks
> very similar.
>
> At the moment, we do not allow userspace to allocate objects in stolen,
> so there is neither the memory pressure to trigger stolen eviction nor
> any purgeable objects inside the stolen arena. However, this will change
> in the near future, and so better management and defragmentation of
> stolen memory will become a real issue.
>
> v2: Remember to remove the drm_mm_node.
>
> v3: Rebased to the latest drm-intel-nightly (Ankit)
>
> v4: corrected if-else braces format (Tvrtko/kerneldoc)
>
> v5: Rebased to the latest drm-intel-nightly (Ankit)
> Added a seperate list to maintain purgable objects from stolen memory
> region (Chris/Daniel)
>
> Testcase: igt/gem_stolen
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma at intel.com>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 4 +-
> drivers/gpu/drm/i915/i915_drv.h | 17 +++-
> drivers/gpu/drm/i915/i915_gem.c | 16 +++
> drivers/gpu/drm/i915/i915_gem_stolen.c | 176 ++++++++++++++++++++++++++++-----
> drivers/gpu/drm/i915/intel_pm.c | 4 +-
> 5 files changed, 187 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 7a28de5..0db8c47 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -179,7 +179,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
> seq_puts(m, ")");
> }
> if (obj->stolen)
> - seq_printf(m, " (stolen: %08llx)", obj->stolen->start);
> + seq_printf(m, " (stolen: %08llx)", obj->stolen->base.start);
> if (obj->pin_display || obj->fault_mappable) {
> char s[3], *t = s;
> if (obj->pin_display)
> @@ -258,7 +258,7 @@ static int obj_rank_by_stolen(void *priv,
> struct drm_i915_gem_object *b =
> container_of(B, struct drm_i915_gem_object, obj_exec_link);
>
> - return a->stolen->start - b->stolen->start;
> + return a->stolen->base.start - b->stolen->base.start;
> }
>
> static int i915_gem_stolen_list_info(struct seq_file *m, void *data)
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index e6ef083..37ee32d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -841,6 +841,12 @@ struct i915_ctx_hang_stats {
> bool banned;
> };
>
> +struct i915_stolen_node {
> + struct drm_mm_node base;
> + struct list_head mm_link;
> + struct drm_i915_gem_object *obj;
> +};
> +
> /* This must match up with the value previously used for execbuf2.rsvd1. */
> #define DEFAULT_CONTEXT_HANDLE 0
>
> @@ -1268,6 +1274,13 @@ struct i915_gem_mm {
> */
> struct list_head unbound_list;
>
> + /**
> + * List of stolen objects that have been marked as purgeable and
> + * thus available for reaping if we need more space for a new
> + * allocation. Ordered by time of marking purgeable.
> + */
> + struct list_head stolen_list;
> +
> /** Usable portion of the GTT for GEM */
> unsigned long stolen_base; /* limited to low memory (32-bit) */
>
> @@ -2026,7 +2039,7 @@ struct drm_i915_gem_object {
> struct list_head vma_list;
>
> /** Stolen memory for this object, instead of being backed by shmem. */
> - struct drm_mm_node *stolen;
> + struct i915_stolen_node *stolen;
> struct list_head global_list;
>
> struct list_head ring_list[I915_NUM_RINGS];
> @@ -2034,6 +2047,7 @@ struct drm_i915_gem_object {
> struct list_head obj_exec_link;
>
> struct list_head batch_pool_link;
> + struct list_head tmp_link;
>
> /**
> * This is set if the object is on the active lists (has pending
> @@ -2150,6 +2164,7 @@ struct drm_i915_gem_object {
> };
> };
> #define to_intel_bo(x) container_of(x, struct drm_i915_gem_object, base)
> +#define I915_BO_IS_ACTIVE(__obj) (__obj->active)
>
> void i915_gem_track_fb(struct drm_i915_gem_object *old,
> struct drm_i915_gem_object *new,
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 6568a7f..85025b1 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4228,6 +4228,20 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
> if (obj->madv == I915_MADV_DONTNEED && obj->pages == NULL)
> i915_gem_object_truncate(obj);
>
> + if (obj->stolen) {
> + switch (obj->madv) {
> + case I915_MADV_WILLNEED:
> + list_del_init(&obj->stolen->mm_link);
> + break;
> + case I915_MADV_DONTNEED:
> + list_move(&obj->stolen->mm_link,
> + &dev_priv->mm.stolen_list);
> + break;
> + default:
> + break;
> + }
> + }
> +
> args->retained = obj->madv != __I915_MADV_PURGED;
>
> out:
> @@ -4248,6 +4262,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
> INIT_LIST_HEAD(&obj->obj_exec_link);
> INIT_LIST_HEAD(&obj->vma_list);
> INIT_LIST_HEAD(&obj->batch_pool_link);
> + INIT_LIST_HEAD(&obj->tmp_link);
>
> obj->ops = ops;
>
> @@ -4898,6 +4913,7 @@ i915_gem_load(struct drm_device *dev)
> INIT_LIST_HEAD(&dev_priv->context_list);
> INIT_LIST_HEAD(&dev_priv->mm.unbound_list);
> INIT_LIST_HEAD(&dev_priv->mm.bound_list);
> + INIT_LIST_HEAD(&dev_priv->mm.stolen_list);
> INIT_LIST_HEAD(&dev_priv->mm.fence_list);
> for (i = 0; i < I915_NUM_RINGS; i++)
> init_ring_lists(&dev_priv->ring[i]);
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index 99f2bce..430e0b0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -52,8 +52,8 @@ int i915_gem_stolen_insert_node(struct drm_i915_private *dev_priv,
> return -ENODEV;
>
> mutex_lock(&dev_priv->mm.stolen_lock);
> - ret = drm_mm_insert_node(&dev_priv->mm.stolen, node, size, alignment,
> - DRM_MM_SEARCH_DEFAULT);
> + ret = drm_mm_insert_node(&dev_priv->mm.stolen, node,
> + size, alignment, DRM_MM_SEARCH_DEFAULT);
There is no change here.
> mutex_unlock(&dev_priv->mm.stolen_lock);
>
> return ret;
> @@ -407,18 +407,19 @@ static void i915_gem_object_put_pages_stolen(struct drm_i915_gem_object *obj)
> kfree(obj->pages);
> }
>
> -
>
> static void
> i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
> {
> struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
>
> if (obj->stolen) {
> - i915_gem_stolen_remove_node(dev_priv, obj->stolen);
> + list_del(&obj->stolen->mm_link);
> + i915_gem_stolen_remove_node(dev_priv, &obj->stolen->base);
> kfree(obj->stolen);
> obj->stolen = NULL;
> }
> }
> +
> static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
> .get_pages = i915_gem_object_get_pages_stolen,
> .put_pages = i915_gem_object_put_pages_stolen,
> @@ -427,7 +428,7 @@ static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
>
> static struct drm_i915_gem_object *
> _i915_gem_object_create_stolen(struct drm_device *dev,
> - struct drm_mm_node *stolen)
> + struct i915_stolen_node *stolen)
> {
> struct drm_i915_gem_object *obj;
>
> @@ -435,17 +436,21 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
> if (obj == NULL)
> return NULL;
>
> - drm_gem_private_object_init(dev, &obj->base, stolen->size);
> + drm_gem_private_object_init(dev, &obj->base, stolen->base.size);
> i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
>
> obj->pages = i915_pages_create_for_stolen(dev,
> - stolen->start, stolen->size);
> + stolen->base.start,
> + stolen->base.size);
> if (obj->pages == NULL)
> goto cleanup;
>
> i915_gem_object_pin_pages(obj);
> obj->stolen = stolen;
>
> + stolen->obj = obj;
> + INIT_LIST_HEAD(&stolen->mm_link);
> +
> obj->base.read_domains = I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT;
> obj->cache_level = HAS_LLC(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
>
> @@ -456,36 +461,157 @@ cleanup:
> return NULL;
> }
>
> -struct drm_i915_gem_object *
> -i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
> +static bool mark_free(struct drm_i915_gem_object *obj, struct list_head *unwind)
> +{
> + if (obj->stolen == NULL)
> + return false;
As Chris said, just WARN_ON instead of BUG_ON please.
> + if (obj->madv != I915_MADV_DONTNEED)
> + return false;
> +
> + if (obj->pin_display)
> + return false;
> +
> + if (I915_BO_IS_ACTIVE(obj))
> + return false;
Chris already spotted this will prevent callers from working as they expect.
> + list_add(&obj->tmp_link, unwind);
> + return drm_mm_scan_add_block(&obj->stolen->base);
> +}
> +
> +static int
> +stolen_evict(struct drm_i915_private *dev_priv, u64 size)
> {
> - struct drm_i915_private *dev_priv = dev->dev_private;
> struct drm_i915_gem_object *obj;
> - struct drm_mm_node *stolen;
> + struct list_head unwind, evict;
> + struct i915_stolen_node *iter;
> int ret;
>
> - if (!drm_mm_initialized(&dev_priv->mm.stolen))
> - return NULL;
> + drm_mm_init_scan(&dev_priv->mm.stolen, size, 0, 0);
> + INIT_LIST_HEAD(&unwind);
> +
> + list_for_each_entry(iter, &dev_priv->mm.stolen_list, mm_link) {
> + if (I915_BO_IS_ACTIVE(iter->obj))
> + continue;
> +
> + if (mark_free(iter->obj, &unwind))
> + goto found;
> + }
> +
> + list_for_each_entry(iter, &dev_priv->mm.stolen_list, mm_link) {
> + if (!I915_BO_IS_ACTIVE(iter->obj))
> + continue;
> +
> + if (mark_free(iter->obj, &unwind))
> + goto found;
> + }
> +
> +found:
> + INIT_LIST_HEAD(&evict);
> + while (!list_empty(&unwind)) {
> + obj = list_first_entry(&unwind,
> + struct drm_i915_gem_object,
> + tmp_link);
> + list_del_init(&obj->tmp_link);
> +
> + if (drm_mm_scan_remove_block(&obj->stolen->base)) {
> + list_add(&obj->tmp_link, &evict);
> + drm_gem_object_reference(&obj->base);
> + }
In what circumstances can drm_mm_scan_remove_block fail?
> + }
> +
> + ret = 0;
> + while (!list_empty(&evict)) {
> + obj = list_first_entry(&evict,
> + struct drm_i915_gem_object,
> + tmp_link);
> + list_del_init(&obj->tmp_link);
> +
> + if (ret == 0) {
> + struct i915_vma *vma, *vma_next;
> +
> + list_for_each_entry_safe(vma, vma_next,
> + &obj->vma_list,
> + vma_link)
> + if (i915_vma_unbind(vma))
> + break;
Because of VMA unbinding stolen creation now again needs struct_mutex. I
think putting held assertion somewhere in the call chain is now appropriate.
The rest looked good to me.
Regards,
Tvrtko
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