Revert "x86, NUMA: Fix fakenuma boot failure" (37f8527d) · Commits · 戴 / test

Andreas Herrmann reported that ("x86, NUMA: Fix fakenuma boot failure") causes certain physical NUMA topologies (for example AMD Magny-Cours) to move sibling cpus to a single node when in reality they are in separate domains. This may result in some nodes being completely void of cpus, which doesn't accurately represent the correct topology. The system will boot, but will have suboptimal NUMA performance. This commit was intended as a fix for NUMA emulation, but should not cause a regression for real NUMA machines as a side effect. ( There will be a separate fix for the numa-debug code, which will not affect physical topologies. ) Reported-by:

Andreas Herrmann <herrmann.der.user@googlemail.com> Signed-off-by:

David Rientjes <rientjes@google.com> Acked-by:

KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.00.1104201918110.12634@chino.kir.corp.google.com Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/smpboot.c

+0 −23

Original line number	Diff line number	Diff line
		@@ -312,26 +312,6 @@ void __cpuinit smp_store_cpu_info(int id)
		identify_secondary_cpu(c);
		}

		static void __cpuinit check_cpu_siblings_on_same_node(int cpu1, int cpu2)
		{
		int node1 = early_cpu_to_node(cpu1);
		int node2 = early_cpu_to_node(cpu2);

		/*
		* Our CPU scheduler assumes all logical cpus in the same physical cpu
		* share the same node. But, buggy ACPI or NUMA emulation might assign
		* them to different node. Fix it.
		*/
		if (node1 != node2) {
		pr_warning("CPU %d in node %d and CPU %d in node %d are in the same physical CPU. forcing same node %d\n",
		cpu1, node1, cpu2, node2, node2);

		numa_remove_cpu(cpu1);
		numa_set_node(cpu1, node2);
		numa_add_cpu(cpu1);
		}
		}

		static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
		{
		cpumask_set_cpu(cpu1, cpu_sibling_mask(cpu2));
		@@ -340,7 +320,6 @@ static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
		cpumask_set_cpu(cpu2, cpu_core_mask(cpu1));
		cpumask_set_cpu(cpu1, cpu_llc_shared_mask(cpu2));
		cpumask_set_cpu(cpu2, cpu_llc_shared_mask(cpu1));
		check_cpu_siblings_on_same_node(cpu1, cpu2);
		}


		@@ -382,12 +361,10 @@ void __cpuinit set_cpu_sibling_map(int cpu)
		per_cpu(cpu_llc_id, cpu) == per_cpu(cpu_llc_id, i)) {
		cpumask_set_cpu(i, cpu_llc_shared_mask(cpu));
		cpumask_set_cpu(cpu, cpu_llc_shared_mask(i));
		check_cpu_siblings_on_same_node(cpu, i);
		}
		if (c->phys_proc_id == cpu_data(i).phys_proc_id) {
		cpumask_set_cpu(i, cpu_core_mask(cpu));
		cpumask_set_cpu(cpu, cpu_core_mask(i));
		check_cpu_siblings_on_same_node(cpu, i);
		/*
		* Does this new cpu bringup a new core?
		*/

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