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Subject[PATCH 48/63] sched: numa: stay on the same node if CLONE_VM
Date
From: Rik van Riel <riel@redhat.com>

A newly spawned thread inside a process should stay on the same
NUMA node as its parent. This prevents processes from being "torn"
across multiple NUMA nodes every time they spawn a new thread.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/sched.h | 2 +-
kernel/fork.c | 2 +-
kernel/sched/core.c | 14 +++++++++-----
3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 15888f5..4f51ceb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2005,7 +2005,7 @@ extern void wake_up_new_task(struct task_struct *tsk);
#else
static inline void kick_process(struct task_struct *tsk) { }
#endif
-extern void sched_fork(struct task_struct *p);
+extern void sched_fork(unsigned long clone_flags, struct task_struct *p);
extern void sched_dead(struct task_struct *p);

extern void proc_caches_init(void);
diff --git a/kernel/fork.c b/kernel/fork.c
index 3b1f6af..51f6c4b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1310,7 +1310,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
#endif

/* Perform scheduler related setup. Assign this task to a CPU. */
- sched_fork(p);
+ sched_fork(clone_flags, p);

retval = perf_event_init_task(p);
if (retval)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 123ac92..336a8ba 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1699,7 +1699,7 @@ int wake_up_state(struct task_struct *p, unsigned int state)
*
* __sched_fork() is basic setup used by init_idle() too:
*/
-static void __sched_fork(struct task_struct *p)
+static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
{
p->on_rq = 0;

@@ -1732,11 +1732,15 @@ static void __sched_fork(struct task_struct *p)
p->mm->numa_scan_seq = 0;
}

+ if (clone_flags & CLONE_VM)
+ p->numa_preferred_nid = current->numa_preferred_nid;
+ else
+ p->numa_preferred_nid = -1;
+
p->node_stamp = 0ULL;
p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
p->numa_migrate_seq = 1;
p->numa_scan_period = sysctl_numa_balancing_scan_delay;
- p->numa_preferred_nid = -1;
p->numa_work.next = &p->numa_work;
p->numa_faults = NULL;
p->numa_faults_buffer = NULL;
@@ -1768,12 +1772,12 @@ void set_numabalancing_state(bool enabled)
/*
* fork()/clone()-time setup:
*/
-void sched_fork(struct task_struct *p)
+void sched_fork(unsigned long clone_flags, struct task_struct *p)
{
unsigned long flags;
int cpu = get_cpu();

- __sched_fork(p);
+ __sched_fork(clone_flags, p);
/*
* We mark the process as running here. This guarantees that
* nobody will actually run it, and a signal or other external
@@ -4304,7 +4308,7 @@ void init_idle(struct task_struct *idle, int cpu)

raw_spin_lock_irqsave(&rq->lock, flags);

- __sched_fork(idle);
+ __sched_fork(0, idle);
idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();

--
1.8.1.4


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