From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: mm/workingset.c: avoid unnecessary max_nodes estimation in count_shadow_nodes() If list_lru_shrink_count is 0, we always return SHRINK_EMPTY regardless of the value of max_nodes. So we can return early if nodes == 0 to save some cpu cycles of approximating a reasonable limit for the nodes. Link: https://lkml.kernel.org/r/20210123073825.46709-1-linmiaohe@xxxxxxxxxx Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/workingset.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/mm/workingset.c~mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes +++ a/mm/workingset.c @@ -461,6 +461,8 @@ static unsigned long count_shadow_nodes( unsigned long pages; nodes = list_lru_shrink_count(&shadow_nodes, sc); + if (!nodes) + return SHRINK_EMPTY; /* * Approximate a reasonable limit for the nodes @@ -503,9 +505,6 @@ static unsigned long count_shadow_nodes( max_nodes = pages >> (XA_CHUNK_SHIFT - 3); - if (!nodes) - return SHRINK_EMPTY; - if (nodes <= max_nodes) return 0; return nodes - max_nodes; _
