The patch titled
Subject: lib/group_cpus: drop unneeded cpumask_empty() call in __group_cpus_evenly()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-group_cpus-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-group_cpus-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yury Norov <yury.norov@xxxxxxxxx>
Subject: lib/group_cpus: drop unneeded cpumask_empty() call in __group_cpus_evenly()
Date: Thu, 28 Dec 2023 12:09:33 -0800
The function is called twice. First time it's called with cpumask_present
as a parameter, which can't be empty. Second time it's called with a mask
created with cpumask_andnot(), which returns false if the result is an
empty mask.
We can safely drop redundant cpumask_empty() call from the
__group_cpus_evenly() and save few cycles.
Link: https://lkml.kernel.org/r/20231228200936.2475595-7-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/group_cpus.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/lib/group_cpus.c~lib-group_cpus-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly
+++ a/lib/group_cpus.c
@@ -259,9 +259,6 @@ static int __group_cpus_evenly(unsigned
nodemask_t nodemsk = NODE_MASK_NONE;
struct node_groups *node_groups;
- if (cpumask_empty(cpu_mask))
- return 0;
-
nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
/*
@@ -401,9 +398,14 @@ struct cpumask *group_cpus_evenly(unsign
curgrp = 0;
else
curgrp = nr_present;
- cpumask_andnot(npresmsk, cpu_possible_mask, npresmsk);
- ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
- npresmsk, nmsk, masks);
+
+ if (cpumask_andnot(npresmsk, cpu_possible_mask, npresmsk))
+ /* If npresmsk is not empty */
+ ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
+ npresmsk, nmsk, masks);
+ else
+ ret = 0;
+
if (ret >= 0)
nr_others = ret;
_
Patches currently in -mm which might be from yury.norov@xxxxxxxxx are
cpumask-introduce-for_each_cpu_and_from.patch
lib-group_cpus-optimize-inner-loop-in-grp_spread_init_one.patch
lib-group_cpus-relax-atomicity-requirement-in-grp_spread_init_one.patch
lib-group_cpus-optimize-outer-loop-in-grp_spread_init_one.patch
lib-group_cpus-dont-zero-cpumasks-in-group_cpus_evenly-on-allocation.patch
lib-group_cpus-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly.patch
cpumask-define-cleanup-function-for-cpumasks.patch
lib-group_cpus-rework-group_cpus_evenly.patch
lib-group_cpus-simplify-group_cpus_evenly-for-more.patch
