x86, numa: Use near(er) online node instead of roundrobin for NUMA (d9c2d5ac) · Commits · 戴 / test

CPU to node mapping is set via the following sequence: 1. numa_init_array(): Set up roundrobin from cpu to online node 2. init_cpu_to_node(): Set that according to apicid_to_node[] according to srat only handle the node that is online, and leave other cpu on node without ram (aka not online) to still roundrobin. 3. later call srat_detect_node for Intel/AMD, will use first_online node or nearby node. Problem is that setup_per_cpu_areas() is not called between 2 and 3, the per_cpu for cpu on node with ram is on different node, and could put that on node with two hops away. So try to optimize this and add find_near_online_node() and call init_cpu_to_node(). Signed-off-by:

Yinghai Lu <yinghai@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: David Rientjes <rientjes@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <4B07A739.3030104@kernel.org> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/intel.c

+5 −1

Original line number	Original line	Diff line number	Diff line
	@@ -263,8 +263,12 @@ static void __cpuinit srat_detect_node(struct cpuinfo_x86 *c)
	/* Don't do the funky fallback heuristics the AMD version employs		/* Don't do the funky fallback heuristics the AMD version employs
	for now. */		for now. */
	node = apicid_to_node[apicid];		node = apicid_to_node[apicid];
	if (node == NUMA_NO_NODE \|\| !node_online(node))		if (node == NUMA_NO_NODE)
	node = first_node(node_online_map);		node = first_node(node_online_map);
			else if (!node_online(node)) {
			/* reuse the value from init_cpu_to_node() */
			node = cpu_to_node(cpu);
			}
	numa_set_node(cpu, node);		numa_set_node(cpu, node);

	printk(KERN_INFO "CPU %d/0x%x -> Node %d\n", cpu, apicid, node);		printk(KERN_INFO "CPU %d/0x%x -> Node %d\n", cpu, apicid, node);

arch/x86/mm/numa_64.c

+20 −1

Original line number	Original line	Diff line number	Diff line
	@@ -764,6 +764,25 @@ static __init int numa_setup(char *opt)
	early_param("numa", numa_setup);		early_param("numa", numa_setup);

	#ifdef CONFIG_NUMA		#ifdef CONFIG_NUMA

			static __init int find_near_online_node(int node)
			{
			int n, val;
			int min_val = INT_MAX;
			int best_node = -1;

			for_each_online_node(n) {
			val = node_distance(node, n);

			if (val < min_val) {
			min_val = val;
			best_node = n;
			}
			}

			return best_node;
			}

	/*		/*
	* Setup early cpu_to_node.		* Setup early cpu_to_node.
	*		*
	@@ -795,7 +814,7 @@ void __init init_cpu_to_node(void)
	if (node == NUMA_NO_NODE)		if (node == NUMA_NO_NODE)
	continue;		continue;
	if (!node_online(node))		if (!node_online(node))
	continue;		node = find_near_online_node(node);
	numa_set_node(cpu, node);		numa_set_node(cpu, node);
	}		}
	}		}

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