The patch titled Subject: lib/group_cpus.c: drop unneeded cpumask_empty() call in __group_cpus_evenly() has been added to the -mm mm-nonmm-unstable branch. Its filename is lib-group_cpusc-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_cpusc-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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yury Norov <yury.norov@xxxxxxxxx> Subject: lib/group_cpus.c: drop unneeded cpumask_empty() call in __group_cpus_evenly() Date: Thu, 7 Dec 2023 12:39:00 -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/20231207203900.859776-7-yury.norov@xxxxxxxxx Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Ming Lei <ming.lei@xxxxxxxxxx> 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_cpusc-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly +++ a/lib/group_cpus.c @@ -252,9 +252,6 @@ 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); /* @@ -394,9 +391,14 @@ 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-relax-atomicity-requirement-in-grp_spread_init_one.patch lib-group_cpus-optimize-inner-loop-in-grp_spread_init_one.patch lib-group_cpus-optimize-outer-loop-in-grp_spread_init_one.patch lib-cgroup_cpusc-dont-zero-cpumasks-in-group_cpus_evenly-on-allocation.patch lib-group_cpusc-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly.patch