+ mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch added to -mm tree

+ mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/workingset.c: avoid unnecessary max_nodes estimation in count_shadow_nodes()
has been added to the -mm tree.  Its filename is
     mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
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@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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;
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-hugetlb-fix-potential-double-free-in-hugetlb_register_node-error-path.patch
mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch
mm-hugetlb-use-helper-huge_page_order-and-pages_per_huge_page.patch
mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch
z3fold-remove-unused-attribute-for-release_z3fold_page.patch
z3fold-simplify-the-zhdr-initialization-code-in-init_z3fold_page.patch
mm-compaction-remove-duplicated-vm_bug_on_page-pagelocked.patch
hugetlbfs-remove-useless-bug_oninode-in-hugetlbfs_setattr.patch
hugetlbfs-use-helper-macro-default_hstate-in-init_hugetlbfs_fs.patch
hugetlbfs-correct-obsolete-function-name-in-hugetlbfs_read_iter.patch
hugetlbfs-remove-meaningless-variable-avoid_reserve.patch
mm-zsmallocc-convert-to-use-kmem_cache_zalloc-in-cache_alloc_zspage.patch