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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: Christian König <christian.koenig@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210820120528.81114-3-christian.koenig@amd.com
This commit is contained in:
Christian König 2021-04-01 15:45:33 +02:00
parent 880121be11
commit 450b2622bc
1 changed files with 22 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/gpu/drm/ttm/ttm_pool.c
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@ -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) {