The patch titled
Subject: lib-optimize-cpumask_local_spread-v8
has been added to the -mm tree. Its filename is
lib-optimize-cpumask_local_spread-v8.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/lib-optimize-cpumask_local_spread-v8.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/lib-optimize-cpumask_local_spread-v8.patch
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------------------------------------------------------
From: Yuqi Jin <jinyuqi@xxxxxxxxxx>
Subject: lib-optimize-cpumask_local_spread-v8
1. Fix confusing comments
2. Improve the loop for choosing the nearest node.
Link: https://lkml.kernel.org/r/1609759109-62925-1-git-send-email-zhangshaokun@xxxxxxxxxxxxx
Signed-off-by: Yuqi Jin <jinyuqi@xxxxxxxxxx>
Signed-off-by: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cpumask.h | 2 -
lib/cpumask.c | 61 +++++++++++++++++++-------------------
2 files changed, 32 insertions(+), 31 deletions(-)
--- a/include/linux/cpumask.h~lib-optimize-cpumask_local_spread-v8
+++ a/include/linux/cpumask.h
@@ -189,7 +189,7 @@ static inline unsigned int cpumask_any_b
return 1;
}
-static inline unsigned int cpumask_local_spread(unsigned int i, int node)
+static inline unsigned int cpumask_local_spread(unsigned int cpu_index, int node)
{
return 0;
}
--- a/lib/cpumask.c~lib-optimize-cpumask_local_spread-v8
+++ a/lib/cpumask.c
@@ -193,80 +193,81 @@ void __init free_bootmem_cpumask_var(cpu
}
#endif
-static int find_nearest_node(int node, bool *used)
+static int find_nearest_node(int node, nodemask_t nodes)
{
int i, min_dist, node_id = -1;
/* Choose the first unused node to compare */
- for (i = 0; i < nr_node_ids; i++) {
- if (used[i] == false) {
+ for (i = 0; i < nr_node_ids; i++)
+ if (!node_isset(i, nodes)) {
min_dist = node_distance(node, i);
node_id = i;
break;
}
- }
/* Compare and return the nearest node */
- for (i = 0; i < nr_node_ids; i++) {
- if (node_distance(node, i) < min_dist && used[i] == false) {
+ for (i = 0; i < nr_node_ids; i++)
+ if (!node_isset(i, nodes) &&
+ node_distance(node, i) < min_dist) {
min_dist = node_distance(node, i);
node_id = i;
}
- }
return node_id;
}
/**
* cpumask_local_spread - select the i'th cpu with local numa cpu's first
- * @i: index number
+ * @cpu_index: index number
* @node: local numa_node
*
* This function selects an online CPU according to a numa aware policy;
- * local cpus are returned first, followed by the next one which is the
- * nearest unused NUMA node based on NUMA distance, then it wraps around.
+ * Loop through all the online CPUs on the system. Start with the CPUs on
+ * 'node', then fall back to CPUs on NUMA nodes which are increasingly far
+ * away.
*
- * It's not very efficient, but useful for setup.
+ * This function is not very efficient, especially for large 'cpu_index'
+ * because it loops over the same CPUs on each call and does not remember
+ * its state from previous calls, but it is useful for setup.
*/
-unsigned int cpumask_local_spread(unsigned int i, int node)
+unsigned int cpumask_local_spread(unsigned int cpu_index, int node)
{
- static DEFINE_SPINLOCK(spread_lock);
- static bool used[MAX_NUMNODES];
- unsigned long flags;
- int cpu, hk_flags, j, id;
+ int cpu, hk_flags, j, ncpus, id;
const struct cpumask *mask;
+ struct cpumask nmsk;
+ nodemask_t nodes_msk;
hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ;
mask = housekeeping_cpumask(hk_flags);
/* Wrap: we always want a cpu. */
- i %= cpumask_weight(mask);
+ cpu_index %= cpumask_weight(mask);
if (node == NUMA_NO_NODE) {
for_each_cpu(cpu, mask) {
- if (i-- == 0)
+ if (cpu_index-- == 0)
return cpu;
}
} else {
- spin_lock_irqsave(&spread_lock, flags);
- memset(used, 0, nr_node_ids * sizeof(bool));
/* select node according to the distance from local node */
+ nodes_clear(nodes_msk);
for (j = 0; j < nr_node_ids; j++) {
- id = find_nearest_node(node, used);
+ id = find_nearest_node(node, nodes_msk);
if (id < 0)
break;
-
- for_each_cpu_and(cpu, cpumask_of_node(id), mask)
- if (i-- == 0) {
- spin_unlock_irqrestore(&spread_lock,
- flags);
+ cpumask_and(&nmsk, mask, cpumask_of_node(id));
+ ncpus = cpumask_weight(&nmsk);
+ if (cpu_index >= ncpus) {
+ cpu_index -= ncpus;
+ node_set(id, nodes_msk);
+ continue;
+ }
+ for_each_cpu(cpu, &nmsk)
+ if (cpu_index-- == 0)
return cpu;
- }
- used[id] = true;
}
- spin_unlock_irqrestore(&spread_lock, flags);
for_each_cpu(cpu, mask)
- if (i-- == 0)
+ if (cpu_index-- == 0)
return cpu;
}
BUG();
_
Patches currently in -mm which might be from jinyuqi@xxxxxxxxxx are
lib-optimize-cpumask_local_spread.patch
lib-optimize-cpumask_local_spread-v8.patch
