[PATCH v4] sched/numa: add per-process numa_balancing

From: Gang Li
Date: Thu Sep 29 2022 - 02:44:21 EST

This patch add a new api PR_NUMA_BALANCING in prctl.

A large number of page faults will cause performance loss when numa
balancing is performing. Thus those processes which care about worst-case
performance need numa balancing disabled. Others, on the contrary, allow a
temporary performance loss in exchange for higher average performance, so
enable numa balancing is better for them.

Numa balancing can only be controlled globally by
/proc/sys/kernel/numa_balancing. Due to the above case, we want to
disable/enable numa_balancing per-process instead.

Add numa_balancing under mm_struct. Then use it in task_tick_fair.

Set per-process numa balancing:
prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DISABLE); //disable
prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_ENABLE); //enable
prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DEFAULT); //follow global
Get numa_balancing state:
prctl(PR_NUMA_BALANCING, PR_GET_NUMAB, &ret);
cat /proc/<pid>/status | grep NumaB_enabled

Cc: linux-api@xxxxxxxxxxxxxxx
Signed-off-by: Gang Li <ligang.bdlg@xxxxxxxxxxxxx>
---
Changes in v4:
- code clean: add wrapper function `numa_balancing_enabled`

Changes in v3:
- Fix compile error.

Changes in v2:
- Now PR_NUMA_BALANCING support three states: enabled, disabled, default.
enabled and disabled will ignore global setting, and default will follow
global setting.
---
Documentation/filesystems/proc.rst | 2 ++
fs/proc/task_mmu.c | 19 +++++++++++++++
include/linux/mm_types.h | 3 +++
include/linux/sched/numa_balancing.h | 8 +++++++
include/uapi/linux/prctl.h | 7 ++++++
kernel/fork.c | 3 +++
kernel/sched/core.c | 15 ++++++++++++
kernel/sched/fair.c | 32 ++++++++++++++++++++-----
kernel/sys.c | 35 ++++++++++++++++++++++++++++
9 files changed, 118 insertions(+), 6 deletions(-)

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index e7aafc82be99..b2ddffad015f 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -192,6 +192,7 @@ read the file /proc/PID/status::
VmLib: 1412 kB
VmPTE: 20 kb
VmSwap: 0 kB
+ NumaB_enabled: default
HugetlbPages: 0 kB
CoreDumping: 0
THP_enabled: 1
@@ -273,6 +274,7 @@ It's slow but very precise.
VmPTE size of page table entries
VmSwap amount of swap used by anonymous private data
(shmem swap usage is not included)
+ NumaB_enabled numa balancing state, set by prctl(PR_NUMA_BALANCING, ...)
HugetlbPages size of hugetlb memory portions
CoreDumping process's memory is currently being dumped
(killing the process may lead to a corrupted core)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8b4f3073f8f5..7358a5932e5a 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -19,6 +19,7 @@
#include <linux/shmem_fs.h>
#include <linux/uaccess.h>
#include <linux/pkeys.h>
+#include <linux/sched/numa_balancing.h>

#include <asm/elf.h>
#include <asm/tlb.h>
@@ -75,6 +76,24 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
" kB\nVmPTE:\t", mm_pgtables_bytes(mm) >> 10, 8);
SEQ_PUT_DEC(" kB\nVmSwap:\t", swap);
seq_puts(m, " kB\n");
+#ifdef CONFIG_NUMA_BALANCING
+ seq_puts(m, "NumaB_enabled:\t");
+ switch (mm->numab_enabled) {
+ case NUMAB_DEFAULT:
+ seq_puts(m, "default");
+ break;
+ case NUMAB_DISABLED:
+ seq_puts(m, "disabled");
+ break;
+ case NUMAB_ENABLED:
+ seq_puts(m, "enabled");
+ break;
+ default:
+ seq_puts(m, "unknown");
+ break;
+ }
+ seq_putc(m, '\n');
+#endif
hugetlb_report_usage(m, mm);
}
#undef SEQ_PUT_DEC
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 500e536796ca..d9bfa740d905 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -665,6 +665,9 @@ struct mm_struct {

/* numa_scan_seq prevents two threads remapping PTEs. */
int numa_scan_seq;
+
+ /* Controls whether NUMA balancing is active for this mm. */
+ int numab_enabled;
#endif
/*
* An operation with batched TLB flushing is going on. Anything
diff --git a/include/linux/sched/numa_balancing.h b/include/linux/sched/numa_balancing.h
index 3988762efe15..f4a4cdf264bc 100644
--- a/include/linux/sched/numa_balancing.h
+++ b/include/linux/sched/numa_balancing.h
@@ -16,12 +16,20 @@
#define TNF_MIGRATE_FAIL 0x10

#ifdef CONFIG_NUMA_BALANCING
+enum {
+ NUMAB_DISABLED,
+ NUMAB_ENABLED,
+ NUMAB_DEFAULT
+};
+DECLARE_STATIC_KEY_FALSE(sched_numa_balancing);
extern void task_numa_fault(int last_node, int node, int pages, int flags);
extern pid_t task_numa_group_id(struct task_struct *p);
extern void set_numabalancing_state(bool enabled);
extern void task_numa_free(struct task_struct *p, bool final);
extern bool should_numa_migrate_memory(struct task_struct *p, struct page *page,
int src_nid, int dst_cpu);
+extern bool numa_balancing_enabled(struct task_struct *p);
+extern int numa_balancing_mode(struct mm_struct *mm);
#else
static inline void task_numa_fault(int last_node, int node, int pages,
int flags)
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index a5e06dcbba13..4c57724b04c3 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -284,4 +284,11 @@ struct prctl_mm_map {
#define PR_SET_VMA 0x53564d41
# define PR_SET_VMA_ANON_NAME 0

+/* Set/get enabled per-process numa_balancing */
+#define PR_NUMA_BALANCING 65
+# define PR_SET_NUMAB_DISABLED NUMAB_DISABLED
+# define PR_SET_NUMAB_ENABLED NUMAB_ENABLED
+# define PR_SET_NUMAB_DEFAULT NUMAB_DEFAULT
+# define PR_GET_NUMAB 3
+
#endif /* _LINUX_PRCTL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 844dfdc8c639..1b9254315770 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1133,6 +1133,9 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
init_tlb_flush_pending(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
mm->pmd_huge_pte = NULL;
+#endif
+#ifdef CONFIG_NUMA_BALANCING
+ mm->numab_enabled = NUMAB_DEFAULT;
#endif
mm_init_uprobes_state(mm);
hugetlb_count_init(mm);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a77e8bfbfb5b..12d171978538 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4396,6 +4396,21 @@ void set_numabalancing_state(bool enabled)
__set_numabalancing_state(enabled);
}

+inline int numa_balancing_mode(struct mm_struct *mm)
+{
+ int numab = mm->numab_enabled;
+
+ switch (numab) {
+ case NUMAB_ENABLED:
+ return NUMA_BALANCING_NORMAL;
+ case NUMAB_DISABLED:
+ return NUMA_BALANCING_DISABLED;
+ case NUMAB_DEFAULT:
+ default:
+ return sysctl_numa_balancing_mode;
+ }
+}
+
#ifdef CONFIG_PROC_SYSCTL
static void reset_memory_tiering(void)
{
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ef0e6b3e08ff..87215b3776c9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2818,6 +2818,24 @@ void task_numa_free(struct task_struct *p, bool final)
}
}

+inline bool numa_balancing_enabled(struct task_struct *p)
+{
+ if (p->mm) {
+ int numab = p->mm->numab_enabled;
+
+ switch (numab) {
+ case NUMAB_ENABLED:
+ return true;
+ case NUMAB_DISABLED:
+ return false;
+ case NUMAB_DEFAULT:
+ break;
+ }
+ }
+
+ return static_branch_unlikely(&sched_numa_balancing);
+}
+
/*
* Got a PROT_NONE fault for a page on @node.
*/
@@ -2830,13 +2848,13 @@ 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))
- return;
-
/* for example, ksmd faulting in a user's mm */
if (!p->mm)
return;

+ if (!numa_balancing_enabled(p))
+ return;
+
/*
* NUMA faults statistics are unnecessary for the slow memory
* node for memory tiering mode.
@@ -3151,7 +3169,7 @@ 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 (!numa_balancing_enabled(p))
return;

if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING))
@@ -7996,7 +8014,7 @@ static int 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 (!numa_balancing_enabled(p))
return -1;

if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
@@ -11581,8 +11599,10 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
entity_tick(cfs_rq, se, queued);
}

- if (static_branch_unlikely(&sched_numa_balancing))
+#ifdef CONFIG_NUMA_BALANCING
+ if (numa_balancing_enabled(curr))
task_tick_numa(rq, curr);
+#endif

update_misfit_status(curr, rq);
update_overutilized_status(task_rq(curr));
diff --git a/kernel/sys.c b/kernel/sys.c
index 8a6432465dc5..11720a35455a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -59,6 +59,7 @@
#include <linux/sched/coredump.h>
#include <linux/sched/task.h>
#include <linux/sched/cputime.h>
+#include <linux/sched/numa_balancing.h>
#include <linux/rcupdate.h>
#include <linux/uidgid.h>
#include <linux/cred.h>
@@ -2101,6 +2102,23 @@ static int prctl_set_auxv(struct mm_struct *mm, unsigned long addr,
return 0;
}

+#ifdef CONFIG_NUMA_BALANCING
+static int prctl_pid_numa_balancing_write(int numa_balancing)
+{
+ if (numa_balancing != PR_SET_NUMAB_DEFAULT
+ && numa_balancing != PR_SET_NUMAB_DISABLED
+ && numa_balancing != PR_SET_NUMAB_ENABLED)
+ return -EINVAL;
+ current->mm->numab_enabled = numa_balancing;
+ return 0;
+}
+
+static int prctl_pid_numa_balancing_read(void)
+{
+ return current->mm->numab_enabled;
+}
+#endif
+
static int prctl_set_mm(int opt, unsigned long addr,
unsigned long arg4, unsigned long arg5)
{
@@ -2615,6 +2633,23 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
error = set_syscall_user_dispatch(arg2, arg3, arg4,
(char __user *) arg5);
break;
+#ifdef CONFIG_NUMA_BALANCING
+ case PR_NUMA_BALANCING:
+ switch (arg2) {
+ case PR_SET_NUMAB_DEFAULT:
+ case PR_SET_NUMAB_DISABLED:
+ case PR_SET_NUMAB_ENABLED:
+ error = prctl_pid_numa_balancing_write((int)arg2);
+ break;
+ case PR_GET_NUMAB:
+ error = put_user(prctl_pid_numa_balancing_read(), (int __user *)arg3);
+ break;
+ default:
+ error = -EINVAL;
+ break;
+ }
+ break;
+#endif
#ifdef CONFIG_SCHED_CORE
case PR_SCHED_CORE:
error = sched_core_share_pid(arg2, arg3, arg4, arg5);
--
2.20.1