Commit 450b2622 authored by Christian König's avatar Christian König
Browse files

drm/ttm: optimize the pool shrinker a bit v2 



Switch back to using a spinlock again by moving the IOMMU unmap outside
of the locked region.

This avoids contention especially while freeing pages.

v2: Add a comment explaining why we need sync_shrinkers().

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Acked-by: default avatarHuang Rui <ray.huang@amd.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210820120528.81114-3-christian.koenig@amd.com
parent 880121be

drivers/gpu/drm/ttm/ttm_pool.c

+22 −18
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ static struct ttm_pool_type global_uncached[MAX_ORDER]; 
static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];

static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];



static struct mutex shrinker_lock;

static spinlock_t shrinker_lock;

static struct list_head shrinker_list;

static struct shrinker mm_shrinker;
@@ -263,9 +263,9 @@ static void ttm_pool_type_init(struct ttm_pool_type *pt, struct ttm_pool *pool, 
	spin_lock_init(&pt->lock);

	INIT_LIST_HEAD(&pt->pages);



	mutex_lock(&shrinker_lock);

	spin_lock(&shrinker_lock);

	list_add_tail(&pt->shrinker_list, &shrinker_list);

	mutex_unlock(&shrinker_lock);

	spin_unlock(&shrinker_lock);

}



/* Remove a pool_type from the global shrinker list and free all pages */
@@ -273,9 +273,9 @@ static void ttm_pool_type_fini(struct ttm_pool_type *pt) 
{

	struct page *p;



	mutex_lock(&shrinker_lock);

	spin_lock(&shrinker_lock);

	list_del(&pt->shrinker_list);

	mutex_unlock(&shrinker_lock);

	spin_unlock(&shrinker_lock);



	while ((p = ttm_pool_type_take(pt)))

		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
@@ -313,24 +313,23 @@ static struct ttm_pool_type *ttm_pool_select_type(struct ttm_pool *pool, 
static unsigned int ttm_pool_shrink(void)

{

	struct ttm_pool_type *pt;

	unsigned int num_freed;

	unsigned int num_pages;

	struct page *p;



	mutex_lock(&shrinker_lock);

	spin_lock(&shrinker_lock);

	pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);

	list_move_tail(&pt->shrinker_list, &shrinker_list);

	spin_unlock(&shrinker_lock);



	p = ttm_pool_type_take(pt);

	if (p) {

		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);

		num_freed = 1 << pt->order;

		num_pages = 1 << pt->order;

	} else {

		num_freed = 0;

		num_pages = 0;

	}



	list_move_tail(&pt->shrinker_list, &shrinker_list);

	mutex_unlock(&shrinker_lock);



	return num_freed;

	return num_pages;

}



/* Return the allocation order based for a page */
@@ -530,6 +529,11 @@ void ttm_pool_fini(struct ttm_pool *pool) 
			for (j = 0; j < MAX_ORDER; ++j)

				ttm_pool_type_fini(&pool->caching[i].orders[j]);

	}



	/* We removed the pool types from the LRU, but we need to also make sure

	 * that no shrinker is concurrently freeing pages from the pool.

	 */

	synchronize_shrinkers();

}



/* As long as pages are available make sure to release at least one */
@@ -604,7 +608,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file *m, void *data) 
{

	ttm_pool_debugfs_header(m);



	mutex_lock(&shrinker_lock);

	spin_lock(&shrinker_lock);

	seq_puts(m, "wc\t:");

	ttm_pool_debugfs_orders(global_write_combined, m);

	seq_puts(m, "uc\t:");
@@ -613,7 +617,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file *m, void *data) 
	ttm_pool_debugfs_orders(global_dma32_write_combined, m);

	seq_puts(m, "uc 32\t:");

	ttm_pool_debugfs_orders(global_dma32_uncached, m);

	mutex_unlock(&shrinker_lock);

	spin_unlock(&shrinker_lock);



	ttm_pool_debugfs_footer(m);
@@ -640,7 +644,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m) 


	ttm_pool_debugfs_header(m);



	mutex_lock(&shrinker_lock);

	spin_lock(&shrinker_lock);

	for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i) {

		seq_puts(m, "DMA ");

		switch (i) {
@@ -656,7 +660,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m) 
		}

		ttm_pool_debugfs_orders(pool->caching[i].orders, m);

	}

	mutex_unlock(&shrinker_lock);

	spin_unlock(&shrinker_lock);



	ttm_pool_debugfs_footer(m);

	return 0;
@@ -693,7 +697,7 @@ int ttm_pool_mgr_init(unsigned long num_pages) 
	if (!page_pool_size)

		page_pool_size = num_pages;



	mutex_init(&shrinker_lock);

	spin_lock_init(&shrinker_lock);

	INIT_LIST_HEAD(&shrinker_list);



	for (i = 0; i < MAX_ORDER; ++i) {