[PATCH 10/17] lib/nodemask: add nodemask_weight_{eq,gt,ge,lt,le}

Yury Norov
2021-12-18T21:21:48Z

Kernel code calls nodes_weight() to compare the weight of nodemask with
a given number. We can do it more efficiently with nodes_weight_{eq, ...}
because conditional nodes_weight may stop traversing the nodemask earlier,
as soon as condition is met.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
drivers/acpi/numa/srat.c | 2 +-
include/linux/nodemask.h | 35 +++++++++++++++++++++++++++++++++++
mm/mempolicy.c | 2 +-
3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
index 66a0142dc78c..484b9307f8cc 100644
--- a/drivers/acpi/numa/srat.c
+++ b/drivers/acpi/numa/srat.c
@@ -67,7 +67,7 @@ int acpi_map_pxm_to_node(int pxm)
node = pxm_to_node_map[pxm];

if (node == NUMA_NO_NODE) {
- if (nodes_weight(nodes_found_map) >= MAX_NUMNODES)
+ if (nodes_weight_ge(nodes_found_map, MAX_NUMNODES))
return NUMA_NO_NODE;
node = first_unset_node(nodes_found_map);
__acpi_map_pxm_to_node(pxm, node);
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 567c3ddba2c4..197598e075e9 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -38,6 +38,11 @@
* int nodes_empty(mask) Is mask empty (no bits sets)?
* int nodes_full(mask) Is mask full (all bits sets)?
* int nodes_weight(mask) Hamming weight - number of set bits
+ * bool nodes_weight_eq(src, nbits, num) Hamming Weight is equal to num
+ * bool nodes_weight_gt(src, nbits, num) Hamming Weight is greater than num
+ * bool nodes_weight_ge(src, nbits, num) Hamming Weight is greater than or equal to num
+ * bool nodes_weight_lt(src, nbits, num) Hamming Weight is less than num
+ * bool nodes_weight_le(src, nbits, num) Hamming Weight is less than or equal to num
*
* void nodes_shift_right(dst, src, n) Shift right
* void nodes_shift_left(dst, src, n) Shift left
@@ -240,6 +245,36 @@ static inline int __nodes_weight(const nodemask_t *srcp, unsigned int nbits)
return bitmap_weight(srcp->bits, nbits);
}

+#define nodes_weight_eq(nodemask, num) __nodes_weight_eq(&(nodemask), MAX_NUMNODES, (num))
+static inline int __nodes_weight_eq(const nodemask_t *srcp, unsigned int nbits, int num)
+{
+ return bitmap_weight_eq(srcp->bits, nbits, num);
+}
+
+#define nodes_weight_gt(nodemask, num) __nodes_weight_gt(&(nodemask), MAX_NUMNODES, (num))
+static inline int __nodes_weight_gt(const nodemask_t *srcp, unsigned int nbits, int num)
+{
+ return bitmap_weight_gt(srcp->bits, nbits, num);
+}
+
+#define nodes_weight_ge(nodemask, num) __nodes_weight_ge(&(nodemask), MAX_NUMNODES, (num))
+static inline int __nodes_weight_ge(const nodemask_t *srcp, unsigned int nbits, int num)
+{
+ return bitmap_weight_ge(srcp->bits, nbits, num);
+}
+
+#define nodes_weight_lt(nodemask, num) __nodes_weight_lt(&(nodemask), MAX_NUMNODES, (num))
+static inline int __nodes_weight_lt(const nodemask_t *srcp, unsigned int nbits, int num)
+{
+ return bitmap_weight_lt(srcp->bits, nbits, num);
+}
+
+#define nodes_weight_le(nodemask, num) __nodes_weight_le(&(nodemask), MAX_NUMNODES, (num))
+static inline int __nodes_weight_le(const nodemask_t *srcp, unsigned int nbits, int num)
+{
+ return bitmap_weight_le(srcp->bits, nbits, num);
+}
+
#define nodes_shift_right(dst, src, n) \
__nodes_shift_right(&(dst), &(src), (n), MAX_NUMNODES)
static inline void __nodes_shift_right(nodemask_t *dstp,
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a86590b2507d..27817cf2f2a0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1157,7 +1157,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
* [0-7] - > [3,4,5] moves only 0,1,2,6,7.
*/

- if ((nodes_weight(*from) != nodes_weight(*to)) &&
+ if (!nodes_weight_eq(*from, nodes_weight(*to)) &&
(node_isset(s, *to)))
continue;