Commit ceb1cbac authored May 31, 2012 by Kamalesh Babulal Committed by Ingo Molnar Jun 06, 2012

sched/x86: Calculate booted cores after construction of sibling_mask



Commit 316ad248 ("sched/x86: Rewrite set_cpu_sibling_map()")
broke the booted_cores accounting.

The problem is that the booted_cores accounting needs all the
sibling links set up. So restore the second loop and add a comment as
to why its needed.

On qemu booted with -smp sockets=1,cores=2,threads=2;
Before:
 $ grep cores /proc/cpuinfo
 cpu cores       : 2
 cpu cores       : 1
 cpu cores       : 4
 cpu cores       : 3

With the patch:
 $ grep cores /proc/cpuinfo
 cpu cores       : 2
 cpu cores       : 2
 cpu cores       : 2
 cpu cores       : 2

Reported-by: Prarit Bhargava <prarit@redhat.com>
Reported-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120531073738.GH7511@linux.vnet.ibm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent eea5b551

arch/x86/kernel/smpboot.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -382,6 +382,15 @@ void __cpuinit set_cpu_sibling_map(int cpu)
		if ((i == cpu) \|\| (has_mc && match_llc(c, o)))
		link_mask(llc_shared, cpu, i);

		}

		/*
		* This needs a separate iteration over the cpus because we rely on all
		* cpu_sibling_mask links to be set-up.
		*/
		for_each_cpu(i, cpu_sibling_setup_mask) {
		o = &cpu_data(i);

		if ((i == cpu) \|\| (has_mc && match_mc(c, o))) {
		link_mask(core, cpu, i);