Re: [PATCH 2/2] drm/ttm: optimize the pool shrinker a bit v2

On Thu, Apr 15, 2021 at 07:56:24PM +0800, Christian König wrote:

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

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

Signed-off-by: Christian König christian.koenig@amd.com

Series look good for me as well.

Acked-by: Huang Rui ray.huang@amd.com

---

drivers/gpu/drm/ttm/ttm_pool.c | 44 +++++++++++++++++----------------- 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c index cb38b1a17b09..955836d569cc 100644 --- a/drivers/gpu/drm/ttm/ttm_pool.c +++ b/drivers/gpu/drm/ttm/ttm_pool.c @@ -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 +313,19 @@ 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; 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;
  

• } else {

• num_freed = 0;
  

• }
• list_move_tail(&pt->shrinker_list, &shrinker_list);
• mutex_unlock(&shrinker_lock);

• if (!p)

• return 0;
  
  

• return num_freed;

• ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
• return 1 << pt->order;

}

/* Return the allocation order based for a page */ @@ -530,6 +525,11 @@ 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.
  

• */
  

• sync_shrinkers();

}

/* As long as pages are available make sure to release at least one */ @@ -604,7 +604,7 @@ 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 +613,7 @@ 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 +640,7 @@ 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 +656,7 @@ 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 +693,7 @@ 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) {

-- 2.25.1