From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46612 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935385AbdCVQkq (ORCPT ); Wed, 22 Mar 2017 12:40:46 -0400 Subject: Patch "kernek/fork.c: allocate idle task for a CPU always on its local node" has been added to the 4.4-stable tree To: ak@linux.intel.com, akpm@linux-foundation.org, gregkh@linuxfoundation.org, sumit.semwal@linaro.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Wed, 22 Mar 2017 17:39:06 +0100 Message-ID: <149020074619423@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled kernek/fork.c: allocate idle task for a CPU always on its local node to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kernek-fork.c-allocate-idle-task-for-a-cpu-always-on-its-local-node.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 725fc629ff2545b061407305ae51016c9f928fce Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Mon, 23 May 2016 16:24:05 -0700 Subject: kernek/fork.c: allocate idle task for a CPU always on its local node From: Andi Kleen commit 725fc629ff2545b061407305ae51016c9f928fce upstream. Linux preallocates the task structs of the idle tasks for all possible CPUs. This currently means they all end up on node 0. This also implies that the cache line of MWAIT, which is around the flags field in the task struct, are all located in node 0. We see a noticeable performance improvement on Knights Landing CPUs when the cache lines used for MWAIT are located in the local nodes of the CPUs using them. I would expect this to give a (likely slight) improvement on other systems too. The patch implements placing the idle task in the node of its CPUs, by passing the right target node to copy_process() [akpm@linux-foundation.org: use NUMA_NO_NODE, not a bare -1] Link: http://lkml.kernel.org/r/1463492694-15833-1-git-send-email-andi@firstfloor.org Signed-off-by: Andi Kleen Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Sumit Semwal Signed-off-by: Greg Kroah-Hartman --- kernel/fork.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -331,13 +331,14 @@ void set_task_stack_end_magic(struct tas *stackend = STACK_END_MAGIC; /* for overflow detection */ } -static struct task_struct *dup_task_struct(struct task_struct *orig) +static struct task_struct *dup_task_struct(struct task_struct *orig, int node) { struct task_struct *tsk; struct thread_info *ti; - int node = tsk_fork_get_node(orig); int err; + if (node == NUMA_NO_NODE) + node = tsk_fork_get_node(orig); tsk = alloc_task_struct_node(node); if (!tsk) return NULL; @@ -1270,7 +1271,8 @@ static struct task_struct *copy_process( int __user *child_tidptr, struct pid *pid, int trace, - unsigned long tls) + unsigned long tls, + int node) { int retval; struct task_struct *p; @@ -1323,7 +1325,7 @@ static struct task_struct *copy_process( goto fork_out; retval = -ENOMEM; - p = dup_task_struct(current); + p = dup_task_struct(current, node); if (!p) goto fork_out; @@ -1699,7 +1701,8 @@ static inline void init_idle_pids(struct struct task_struct *fork_idle(int cpu) { struct task_struct *task; - task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0); + task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, + cpu_to_node(cpu)); if (!IS_ERR(task)) { init_idle_pids(task->pids); init_idle(task, cpu); @@ -1744,7 +1747,7 @@ long _do_fork(unsigned long clone_flags, } p = copy_process(clone_flags, stack_start, stack_size, - child_tidptr, NULL, trace, tls); + child_tidptr, NULL, trace, tls, NUMA_NO_NODE); /* * Do this prior waking up the new thread - the thread pointer * might get invalid after that point, if the thread exits quickly. Patches currently in stable-queue which might be from ak@linux.intel.com are queue-4.4/kernek-fork.c-allocate-idle-task-for-a-cpu-always-on-its-local-node.patch