drm/ttm: Increase pool shrinker batch target

The default core shrink target of 128 pages (SHRINK_BATCH) is quite low
relative to how cheap TTM pool shrinking is, and how the free pages are
distributed in page order pools.

We can make the target a bit more aggressive by making it roughly the
average number of pages across all pools, freeing more of the cached
pages every time shrinker core invokes our callback.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20250603112750.34997-3-tvrtko.ursulin@igalia.com

diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index cb44745106bc4c4a5fb62926031678db891d91e5..90b1bb903b930a6dd882b54f30368175ee8a2f70 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -1265,10 +1265,16 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
 }
 EXPORT_SYMBOL(ttm_pool_debugfs);
 
+/* Free average pool number of pages.  */
+#define TTM_SHRINKER_BATCH ((1 << (MAX_PAGE_ORDER / 2)) * NR_PAGE_ORDERS)
+
 /* Test the shrinker functions and dump the result */
 static int ttm_pool_debugfs_shrink_show(struct seq_file *m, void *data)
 {
-       struct shrink_control sc = { .gfp_mask = GFP_NOFS };
+       struct shrink_control sc = {
+               .gfp_mask = GFP_NOFS,
+               .nr_to_scan = TTM_SHRINKER_BATCH,
+       };
 
        fs_reclaim_acquire(GFP_KERNEL);
        seq_printf(m, "%lu/%lu\n", ttm_pool_shrinker_count(mm_shrinker, &sc),
@@ -1326,6 +1332,7 @@ int ttm_pool_mgr_init(unsigned long num_pages)
 
        mm_shrinker->count_objects = ttm_pool_shrinker_count;
        mm_shrinker->scan_objects = ttm_pool_shrinker_scan;
+       mm_shrinker->batch = TTM_SHRINKER_BATCH;
        mm_shrinker->seeks = 1;
 
        shrinker_register(mm_shrinker);