From 50f2d7f682f9c0ed58191d0982fe77888d59d162 Mon Sep 17 00:00:00 2001 From: Nikanth Karthikesan Date: Thu, 30 Sep 2010 17:34:10 +0530 Subject: [PATCH] x86, numa: Assign CPUs to nodes in round-robin manner on fake NUMA commit d9c2d5ac6af87b4491bff107113aaf16f6c2b2d9 "x86, numa: Use near(er) online node instead of roundrobin for NUMA" changed NUMA initialization on Intel to choose the nearest online node or first node. Fake NUMA would be better of with round-robin initialization, instead of the all CPUS on first node. Change the choice of first node, back to round-robin. For testing NUMA kernel behaviour without cpusets and NUMA aware applications, it would be better to have cpus in different nodes, rather than all in a single node. With cpusets migration of tasks scenarios cannot not be tested. I guess having it round-robin shouldn't affect the use cases for all cpus on the first node. The code comments in arch/x86/mm/numa_64.c:759 indicate that this used to be the case, which was changed by commit d9c2d5ac6. It changed from roundrobin to nearer or first node. And I couldn't find any reason for this change in its changelog. Signed-off-by: Nikanth Karthikesan Cc: David Rientjes Signed-off-by: Andrew Morton --- arch/x86/kernel/cpu/intel.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index b438944..6d61786 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -284,9 +284,7 @@ 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 = first_node(node_online_map); - else if (!node_online(node)) { + if (node == NUMA_NO_NODE || !node_online(node)) { /* reuse the value from init_cpu_to_node() */ node = cpu_to_node(cpu); } -- 2.7.4