The patch titled
Subject: cpumask: introduce for_each_cpu_and_from()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
cpumask-introduce-for_each_cpu_and_from.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/cpumask-introduce-for_each_cpu_and_from.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: cpumask: introduce for_each_cpu_and_from()
Date: Thu, 7 Dec 2023 12:38:55 -0800
Patch series "lib/group_cpus: rework grp_spread_init_one() and make it
O(1)", v2.
grp_spread_init_one() implementation is sub-optimal because it traverses
bitmaps from the beginning, instead of picking from the previous
iteration.
Fix it and use find_bit API where appropriate. While here, optimize
cpumasks allocation and drop unneeded cpumask_empty() call.
This patch (of 6):
Similarly to for_each_cpu_and(), introduce a for_each_cpu_and_from(),
which is handy when it's needed to traverse 2 cpumasks or bitmaps,
starting from a given position.
Link: https://lkml.kernel.org/r/20231207203900.859776-1-yury.norov@xxxxxxxxx
Link: https://lkml.kernel.org/r/20231207203900.859776-2-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>
---
include/linux/cpumask.h | 11 +++++++++++
include/linux/find.h | 3 +++
2 files changed, 14 insertions(+)
--- a/include/linux/cpumask.h~cpumask-introduce-for_each_cpu_and_from
+++ a/include/linux/cpumask.h
@@ -333,6 +333,17 @@ unsigned int __pure cpumask_next_wrap(in
for_each_and_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), small_cpumask_bits)
/**
+ * for_each_cpu_and_from - iterate over every cpu in both masks starting from a given cpu
+ * @cpu: the (optionally unsigned) integer iterator
+ * @mask1: the first cpumask pointer
+ * @mask2: the second cpumask pointer
+ *
+ * After the loop, cpu is >= nr_cpu_ids.
+ */
+#define for_each_cpu_and_from(cpu, mask1, mask2) \
+ for_each_and_bit_from(cpu, cpumask_bits(mask1), cpumask_bits(mask2), small_cpumask_bits)
+
+/**
* for_each_cpu_andnot - iterate over every cpu present in one mask, excluding
* those present in another.
* @cpu: the (optionally unsigned) integer iterator
--- a/include/linux/find.h~cpumask-introduce-for_each_cpu_and_from
+++ a/include/linux/find.h
@@ -563,6 +563,9 @@ unsigned long find_next_bit_le(const voi
(bit) = find_next_and_bit((addr1), (addr2), (size), (bit)), (bit) < (size);\
(bit)++)
+#define for_each_and_bit_from(bit, addr1, addr2, size) \
+ for (; (bit) = find_next_and_bit((addr1), (addr2), (size), (bit)), (bit) < (size); (bit)++)
+
#define for_each_andnot_bit(bit, addr1, addr2, size) \
for ((bit) = 0; \
(bit) = find_next_andnot_bit((addr1), (addr2), (size), (bit)), (bit) < (size);\
_
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
