kthread: NUMA aware kthread_create_on_node()
All kthreads being created from a single helper task, they all use memory
from a single node for their kernel stack and task struct.
This patch suite creates kthread_create_on_node(), adding a 'cpu' parameter
to parameters already used by kthread_create().
This parameter serves in allocating memory for the new kthread on its
memory node if possible.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: David Howells <dhowells@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kthread.c b/kernel/kthread.c
index c55afba9..684ab3f 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -27,6 +27,7 @@
/* Information passed to kthread() from kthreadd. */
int (*threadfn)(void *data);
void *data;
+ int node;
/* Result passed back to kthread_create() from kthreadd. */
struct task_struct *result;
@@ -98,10 +99,23 @@
do_exit(ret);
}
+/* called from do_fork() to get node information for about to be created task */
+int tsk_fork_get_node(struct task_struct *tsk)
+{
+#ifdef CONFIG_NUMA
+ if (tsk == kthreadd_task)
+ return tsk->pref_node_fork;
+#endif
+ return numa_node_id();
+}
+
static void create_kthread(struct kthread_create_info *create)
{
int pid;
+#ifdef CONFIG_NUMA
+ current->pref_node_fork = create->node;
+#endif
/* We want our own signal handler (we take no signals by default). */
pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
if (pid < 0) {
@@ -111,15 +125,18 @@
}
/**
- * kthread_create - create a kthread.
+ * kthread_create_on_node - create a kthread.
* @threadfn: the function to run until signal_pending(current).
* @data: data ptr for @threadfn.
+ * @node: memory node number.
* @namefmt: printf-style name for the thread.
*
* Description: This helper function creates and names a kernel
* thread. The thread will be stopped: use wake_up_process() to start
* it. See also kthread_run().
*
+ * If thread is going to be bound on a particular cpu, give its node
+ * in @node, to get NUMA affinity for kthread stack, or else give -1.
* When woken, the thread will run @threadfn() with @data as its
* argument. @threadfn() can either call do_exit() directly if it is a
* standalone thread for which noone will call kthread_stop(), or
@@ -129,15 +146,17 @@
*
* Returns a task_struct or ERR_PTR(-ENOMEM).
*/
-struct task_struct *kthread_create(int (*threadfn)(void *data),
- void *data,
- const char namefmt[],
- ...)
+struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
+ void *data,
+ int node,
+ const char namefmt[],
+ ...)
{
struct kthread_create_info create;
create.threadfn = threadfn;
create.data = data;
+ create.node = node;
init_completion(&create.done);
spin_lock(&kthread_create_lock);
@@ -164,7 +183,7 @@
}
return create.result;
}
-EXPORT_SYMBOL(kthread_create);
+EXPORT_SYMBOL(kthread_create_on_node);
/**
* kthread_bind - bind a just-created kthread to a cpu.