From d9c2d5ac6af87b4491bff107113aaf16f6c2b2d9 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Sat, 21 Nov 2009 00:23:37 -0800 Subject: [PATCH] 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 Cc: Tejun Heo Cc: Linus Torvalds Cc: Thomas Gleixner Cc: H. Peter Anvin Cc: Rusty Russell Cc: David Rientjes Cc: Andrew Morton LKML-Reference: <4B07A739.3030104@kernel.org> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/intel.c | 6 +++++- arch/x86/mm/numa_64.c | 21 ++++++++++++++++++++- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 40e1835b35e8..c900b73f9224 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -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); diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c index 3acd870d316a..83bbc70d11bb 100644 --- a/arch/x86/mm/numa_64.c +++ b/arch/x86/mm/numa_64.c @@ -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); } } -- 2.20.1