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x86, numa: Use near(er) online node instead of roundrobin for NUMA 

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>
This commit is contained in:
Yinghai Lu 2009-11-21 00:23:37 -08:00 committed by Ingo Molnar
parent 021428ad14
commit d9c2d5ac6a
2 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/kernel/cpu/intel.c
View File

@ -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
for now. */
node = apicid_to_node[apicid];
if (node == NUMA_NO_NODE || !node_online(node))
if (node == NUMA_NO_NODE)
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);
printk(KERN_INFO "CPU %d/0x%x -> Node %d\n", cpu, apicid, node);

21
arch/x86/mm/numa_64.c
View File

@ -764,6 +764,25 @@ static __init int numa_setup(char *opt)
early_param("numa", numa_setup);
#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.
*
@ -795,7 +814,7 @@ void __init init_cpu_to_node(void)
if (node == NUMA_NO_NODE)
continue;
if (!node_online(node))
continue;
node = find_near_online_node(node);
numa_set_node(cpu, node);
}
}