linux-kernel - [PATCH 09/40] autonuma: introduce kthread_bind

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Message-Id: <1340888180-15355-10-git-send-email-aarcange@redhat.com>
Date:	Thu, 28 Jun 2012 14:55:49 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:	Hillf Danton <dhillf@...il.com>, Dan Smith <danms@...ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Mike Galbraith <efault@....de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Bharata B Rao <bharata.rao@...il.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Alex Shi <alex.shi@...el.com>,
	Mauricio Faria de Oliveira <mauricfo@...ux.vnet.ibm.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Don Morris <don.morris@...com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: [PATCH 09/40] autonuma: introduce kthread_bind_node()

This function makes it easy to bind the per-node knuma_migrated
threads to their respective NUMA nodes. Those threads take memory from
the other nodes (in round robin with a incoming queue for each remote
node) and they move that memory to their local node.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 include/linux/kthread.h |    1 +
 include/linux/sched.h   |    2 +-
 kernel/kthread.c        |   23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+), 1 deletions(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 0714b24..e733f97 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -33,6 +33,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
 })
 
 void kthread_bind(struct task_struct *k, unsigned int cpu);
+void kthread_bind_node(struct task_struct *p, int nid);
 int kthread_stop(struct task_struct *k);
 int kthread_should_stop(void);
 bool kthread_freezable_should_stop(bool *was_frozen);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4059c0f..699324c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1792,7 +1792,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #define PF_SWAPWRITE	0x00800000	/* Allowed to write to swap */
 #define PF_SPREAD_PAGE	0x01000000	/* Spread page cache over cpuset */
 #define PF_SPREAD_SLAB	0x02000000	/* Spread some slab caches over cpuset */
-#define PF_THREAD_BOUND	0x04000000	/* Thread bound to specific cpu */
+#define PF_THREAD_BOUND	0x04000000	/* Thread bound to specific cpus */
 #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
 #define PF_MEMPOLICY	0x10000000	/* Non-default NUMA mempolicy */
 #define PF_MUTEX_TESTER	0x20000000	/* Thread belongs to the rt mutex tester */
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 3d3de63..48b36f9 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -234,6 +234,29 @@ void kthread_bind(struct task_struct *p, unsigned int cpu)
 EXPORT_SYMBOL(kthread_bind);
 
 /**
+ * kthread_bind_node - bind a just-created kthread to the CPUs of a node.
+ * @p: thread created by kthread_create().
+ * @nid: node (might not be online, must be possible) for @k to run on.
+ *
+ * Description: This function is equivalent to set_cpus_allowed(),
+ * except that @nid doesn't need to be online, and the thread must be
+ * stopped (i.e., just returned from kthread_create()).
+ */
+void kthread_bind_node(struct task_struct *p, int nid)
+{
+	/* Must have done schedule() in kthread() before we set_task_cpu */
+	if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
+		WARN_ON(1);
+		return;
+	}
+
+	/* It's safe because the task is inactive. */
+	do_set_cpus_allowed(p, cpumask_of_node(nid));
+	p->flags |= PF_THREAD_BOUND;
+}
+EXPORT_SYMBOL(kthread_bind_node);
+
+/**
  * kthread_stop - stop a thread created by kthread_create().
  * @k: thread created by kthread_create().
  *
--
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