From: Yafang Shao <laoar.shao@gmail.com>
To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
eddyz87@gmail.com, memxor@gmail.com, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, akpm@linux-foundation.org,
david@kernel.org, gourry@gourry.net, tj@kernel.org,
hannes@cmpxchg.org, mkoutny@suse.com, shakeel.butt@linux.dev,
roman.gushchin@linux.dev, yu.c.chen@intel.com,
zhao1.liu@intel.com, tim.c.chen@linux.intel.com,
lizhe.67@bytedance.com, ziy@nvidia.com, mgorman@suse.de
Cc: bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, Yafang Shao <laoar.shao@gmail.com>
Subject: [RFC PATCH bpf-next v4 1/4] sched: add helpers for numa balancing
Date: Tue, 10 Nov 2026 11:29:10 +0800 [thread overview]
Message-ID: <20261110032913.71974-2-laoar.shao@gmail.com> (raw)
In-Reply-To: <20261110032913.71974-1-laoar.shao@gmail.com>
Introduce task_numab_enabled(), numab_in_normal_mode() and
numab_in_tiering_mode() to replace the direct accesses to the
sched_numa_balancing static key and the sysctl_numa_balancing_mode
bitmask.
No functional change.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
---
include/linux/sched/numa_balancing.h | 36 ++++++++++++++++++++++++++++
kernel/sched/fair.c | 22 ++++++++---------
kernel/sched/sched.h | 1 -
mm/memory-tiers.c | 3 ++-
mm/mempolicy.c | 3 +--
mm/migrate.c | 7 +++---
mm/vmscan.c | 6 ++---
7 files changed, 57 insertions(+), 21 deletions(-)
diff --git a/include/linux/sched/numa_balancing.h b/include/linux/sched/numa_balancing.h
index 52b22c5c396d..61ab161fb481 100644
--- a/include/linux/sched/numa_balancing.h
+++ b/include/linux/sched/numa_balancing.h
@@ -8,6 +8,7 @@
*/
#include <linux/sched.h>
+#include <linux/sched/sysctl.h>
#define TNF_MIGRATED 0x01
#define TNF_NO_GROUP 0x02
@@ -32,6 +33,26 @@ extern void set_numabalancing_state(bool enabled);
extern void task_numa_free(struct task_struct *p, bool final);
bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
int src_nid, int dst_cpu);
+
+extern struct static_key_false sched_numa_balancing;
+
+/* Whether NUMA balancing is enabled. */
+static inline bool task_numab_enabled(void)
+{
+ return static_branch_likely(&sched_numa_balancing);
+}
+
+/* Whether NUMA balancing is in normal mode. */
+static inline bool numab_in_normal_mode(void)
+{
+ return sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL;
+}
+
+/* Whether NUMA balancing is in memory tiering mode. */
+static inline bool numab_in_tiering_mode(void)
+{
+ return sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING;
+}
#else
static inline void task_numa_fault(int last_node, int node, int pages,
int flags)
@@ -52,6 +73,21 @@ static inline bool should_numa_migrate_memory(struct task_struct *p,
{
return true;
}
+
+static inline bool task_numab_enabled(void)
+{
+ return false;
+}
+
+static inline bool numab_in_normal_mode(void)
+{
+ return false;
+}
+
+static inline bool numab_in_tiering_mode(void)
+{
+ return false;
+}
#endif
#endif /* _LINUX_SCHED_NUMA_BALANCING_H */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cfc982205b98..672dda541458 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -39,6 +39,7 @@
#include <linux/sched/cputime.h>
#include <linux/sched/isolation.h>
#include <linux/sched/nohz.h>
+#include <linux/sched/numa_balancing.h>
#include <linux/sched/prio.h>
#include <linux/static_call.h>
@@ -1434,7 +1435,7 @@ static bool exceed_llc_capacity(struct sched_cache_group *grp, int cpu)
if (!sd)
return true;
- if (static_branch_likely(&sched_numa_balancing)) {
+ if (task_numab_enabled()) {
/*
* TBD: RDT exclusive LLC ways reserved should be
* excluded.
@@ -1822,7 +1823,7 @@ static int get_pref_llc(struct task_struct *p, struct sched_cache_group *grp)
* than sched_setnuma() at least -- and thus the
* conflict only exists for a short period of time.
*/
- if (static_branch_likely(&sched_numa_balancing) &&
+ if (task_numab_enabled() &&
p->numa_preferred_nid >= 0 &&
cpu_to_node(mm_sched_cpu) != p->numa_preferred_nid)
mm_sched_llc = -1;
@@ -1923,7 +1924,7 @@ static void get_scan_cpumasks(cpumask_var_t cpus, struct task_struct *p,
#ifdef CONFIG_NUMA_BALANCING
int cpu, curr_cpu, nid, pref_nid;
- if (!static_branch_likely(&sched_numa_balancing))
+ if (!task_numab_enabled())
goto out;
cpu = READ_ONCE(grp->cpu);
@@ -2906,8 +2907,8 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
last_cpupid = folio_xchg_last_cpupid(folio, this_cpupid);
- if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
- !node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
+ if (!numab_in_tiering_mode() && !node_is_toptier(src_nid) &&
+ !cpupid_valid(last_cpupid))
return false;
/*
@@ -4140,7 +4141,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
struct numa_group *ng;
int priv;
- if (!static_branch_likely(&sched_numa_balancing))
+ if (!task_numab_enabled())
return;
/* for example, ksmd faulting in a user's mm */
@@ -4152,8 +4153,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
* node for memory tiering mode.
*/
if (!node_is_toptier(mem_node) &&
- (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ||
- !cpupid_valid(last_cpupid)))
+ (numab_in_tiering_mode() || !cpupid_valid(last_cpupid)))
return;
/* Allocate buffer to track faults on a per-node basis */
@@ -4611,7 +4611,7 @@ static void update_scan_period(struct task_struct *p, int new_cpu)
int src_nid = cpu_to_node(task_cpu(p));
int dst_nid = cpu_to_node(new_cpu);
- if (!static_branch_likely(&sched_numa_balancing))
+ if (!task_numab_enabled())
return;
if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING))
@@ -10702,7 +10702,7 @@ static long migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
unsigned long src_weight, dst_weight;
int src_nid, dst_nid, dist;
- if (!static_branch_likely(&sched_numa_balancing))
+ if (!task_numab_enabled())
return 0;
if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
@@ -15362,7 +15362,7 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
if (queued)
return;
- if (static_branch_unlikely(&sched_numa_balancing))
+ if (task_numab_enabled())
task_tick_numa(rq, curr);
task_tick_cache(rq, curr);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 6c7c5633524a..9b616abf5c9c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2496,7 +2496,6 @@ extern union sched_feat_key sched_feat_keys[__SCHED_FEAT_NR];
#endif /* !CONFIG_JUMP_LABEL */
-extern struct static_key_false sched_numa_balancing;
extern struct static_key_false sched_schedstats;
static inline u64 global_rt_period(void)
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 25e121851b58..c49071261078 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -6,6 +6,7 @@
#include <linux/memory.h>
#include <linux/memory-tiers.h>
#include <linux/notifier.h>
+#include <linux/sched/numa_balancing.h>
#include <linux/sched/sysctl.h>
#include "internal.h"
@@ -64,7 +65,7 @@ static const struct bus_type memory_tier_subsys = {
*/
bool folio_use_access_time(struct folio *folio)
{
- return (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
+ return numab_in_tiering_mode() &&
!node_is_toptier(folio_nid(folio));
}
#endif
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0884c629670d..991b80d5e899 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -887,8 +887,7 @@ bool folio_can_map_prot_numa(struct folio *folio, struct vm_area_struct *vma,
* Skip scanning top tier node if normal numa
* balancing is disabled
*/
- if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
- node_is_toptier(nid))
+ if (!numab_in_normal_mode() && node_is_toptier(nid))
return false;
if (folio_use_access_time(folio))
diff --git a/mm/migrate.c b/mm/migrate.c
index 7bdcdb57652f..4659ecdc4d0c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -41,6 +41,7 @@
#include <linux/ptrace.h>
#include <linux/memory.h>
#include <linux/sched/sysctl.h>
+#include <linux/sched/numa_balancing.h>
#include <linux/memory-tiers.h>
#include <linux/pagewalk.h>
@@ -818,7 +819,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
* memory node, reset cpupid, because that is used to record
* page access time in slow memory node.
*/
- if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) {
+ if (numab_in_tiering_mode()) {
bool f_toptier = node_is_toptier(folio_nid(folio));
bool t_toptier = node_is_toptier(folio_nid(newfolio));
@@ -2717,7 +2718,7 @@ int migrate_misplaced_folio_prepare(struct folio *folio,
if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
int z;
- if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
+ if (!numab_in_tiering_mode())
return -EAGAIN;
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
if (managed_zone(pgdat->node_zones + z))
@@ -2769,7 +2770,7 @@ int migrate_misplaced_folio(struct folio *folio, int node)
if (nr_succeeded) {
count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
count_memcg_events(memcg, NUMA_PAGE_MIGRATE, nr_succeeded);
- if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
+ if (numab_in_tiering_mode()
&& !node_is_toptier(folio_nid(folio))
&& node_is_toptier(node))
mod_lruvec_state(lruvec, PGPROMOTE_SUCCESS, nr_succeeded);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9959ca158ce8..7ef4205b6a4e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -65,6 +65,7 @@
#include <linux/swapops.h>
#include <linux/sched/sysctl.h>
+#include <linux/sched/numa_balancing.h>
#include "internal.h"
#include "page_alloc.h"
@@ -5224,8 +5225,7 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
if (!current_is_kswapd() || sc->order)
return false;
- mark = sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ?
- WMARK_PROMO : WMARK_HIGH;
+ mark = numab_in_tiering_mode() ? WMARK_PROMO : WMARK_HIGH;
for (i = 0; i <= sc->reclaim_idx; i++) {
struct zone *zone = lruvec_pgdat(lruvec)->node_zones + i;
@@ -7131,7 +7131,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)
enum zone_stat_item item;
unsigned long free_pages;
- if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
+ if (numab_in_tiering_mode())
mark = promo_wmark_pages(zone);
else
mark = high_wmark_pages(zone);
--
2.52.0
next prev parent reply other threads:[~2026-11-10 3:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 3:29 [RFC PATCH bpf-next v4 0/4] BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-11-10 3:29 ` Yafang Shao [this message]
2026-11-10 3:37 ` [RFC PATCH bpf-next v4 1/4] sched: add helpers for numa balancing Zi Yan
2026-11-10 3:29 ` [RFC PATCH bpf-next v4 2/4] sched: sample NUMA balancing mode once per path Yafang Shao
2026-11-10 3:29 ` [RFC PATCH bpf-next v4 3/4] sched: add BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-11-10 3:29 ` [RFC PATCH bpf-next v4 4/4] selftests/bpf: add tests for the numab kfuncs Yafang Shao
2026-11-10 3:35 ` [RFC PATCH bpf-next v4 0/4] BPF-based per-cgroup NUMA balancing mode selection Zi Yan
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