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drm/msm/gem: Avoid obj lock in job_run()

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Now that everything that controls which LRU an obj lives in *except* the
backing pages is protected by the LRU lock, add a special path to unpin
in the job_run() path, where we are assured that we already have backing
pages and will not be racing against eviction (because the GEM object's
dma_resv contains the fence that will be signaled when the submit/job
completes).

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/527845/
Link: https://lore.kernel.org/r/20230320144356.803762-10-robdclark@gmail.com
This commit is contained in:
Rob Clark 2023-03-20 07:43:31 -07:00
parent 6c7c8fb863
commit 17b704f1c0
3 changed files with 39 additions and 10 deletions
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44
drivers/gpu/drm/msm/msm_gem.c
View File

@ -61,6 +61,24 @@ static void sync_for_cpu(struct msm_gem_object *msm_obj)
dma_unmap_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0);
}
static void update_lru_active(struct drm_gem_object *obj)
{
struct msm_drm_private *priv = obj->dev->dev_private;
struct msm_gem_object *msm_obj = to_msm_bo(obj);
GEM_WARN_ON(!msm_obj->pages);
if (msm_obj->pin_count) {
drm_gem_lru_move_tail_locked(&priv->lru.pinned, obj);
} else if (msm_obj->madv == MSM_MADV_WILLNEED) {
drm_gem_lru_move_tail_locked(&priv->lru.willneed, obj);
} else {
GEM_WARN_ON(msm_obj->madv != MSM_MADV_DONTNEED);
drm_gem_lru_move_tail_locked(&priv->lru.dontneed, obj);
}
}
static void update_lru_locked(struct drm_gem_object *obj)
{
struct msm_drm_private *priv = obj->dev->dev_private;
@ -72,14 +90,8 @@ static void update_lru_locked(struct drm_gem_object *obj)
GEM_WARN_ON(msm_obj->pin_count);
drm_gem_lru_move_tail_locked(&priv->lru.unbacked, obj);
} else if (msm_obj->pin_count) {
drm_gem_lru_move_tail_locked(&priv->lru.pinned, obj);
} else if (msm_obj->madv == MSM_MADV_WILLNEED) {
drm_gem_lru_move_tail_locked(&priv->lru.willneed, obj);
} else {
GEM_WARN_ON(msm_obj->madv != MSM_MADV_DONTNEED);
drm_gem_lru_move_tail_locked(&priv->lru.dontneed, obj);
update_lru_active(obj);
}
}
@ -489,6 +501,24 @@ void msm_gem_unpin_locked(struct drm_gem_object *obj)
mutex_unlock(&priv->lru.lock);
}
/* Special unpin path for use in fence-signaling path, avoiding the need
* to hold the obj lock by only depending on things that a protected by
* the LRU lock. In particular we know that that we already have backing
* and and that the object's dma_resv has the fence for the current
* submit/job which will prevent us racing against page eviction.
*/
void msm_gem_unpin_active(struct drm_gem_object *obj)
{
struct msm_drm_private *priv = obj->dev->dev_private;
struct msm_gem_object *msm_obj = to_msm_bo(obj);
mutex_lock(&priv->lru.lock);
msm_obj->pin_count--;
GEM_WARN_ON(msm_obj->pin_count < 0);
update_lru_active(obj);
mutex_unlock(&priv->lru.lock);
}
struct msm_gem_vma *msm_gem_get_vma_locked(struct drm_gem_object *obj,
struct msm_gem_address_space *aspace)
{

1
drivers/gpu/drm/msm/msm_gem.h
View File

@ -128,6 +128,7 @@ struct msm_gem_object {
uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj);
int msm_gem_pin_vma_locked(struct drm_gem_object *obj, struct msm_gem_vma *vma);
void msm_gem_unpin_locked(struct drm_gem_object *obj);
void msm_gem_unpin_active(struct drm_gem_object *obj);
struct msm_gem_vma *msm_gem_get_vma_locked(struct drm_gem_object *obj,
struct msm_gem_address_space *aspace);
int msm_gem_get_iova(struct drm_gem_object *obj,

4
drivers/gpu/drm/msm/msm_ringbuffer.c
View File

@ -24,9 +24,7 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
struct drm_gem_object *obj = &submit->bos[i].obj->base;
msm_gem_vma_unpin_fenced(submit->bos[i].vma, fctx);
msm_gem_lock(obj);
msm_gem_unpin_locked(obj);
msm_gem_unlock(obj);
msm_gem_unpin_active(obj);
submit->bos[i].flags &= ~(BO_VMA_PINNED | BO_OBJ_PINNED);
}