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    Subject[tip:sched/urgent] sched/x86: Calculate booted cores after construction of sibling_mask
    Commit-ID:  ceb1cbac8eda66cf0f889def226b4e82f8ff857b
    Gitweb: http://git.kernel.org/tip/ceb1cbac8eda66cf0f889def226b4e82f8ff857b
    Author: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
    AuthorDate: Thu, 31 May 2012 13:07:38 +0530
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Wed, 6 Jun 2012 16:37:59 +0200

    sched/x86: Calculate booted cores after construction of sibling_mask

    Commit 316ad248307fb ("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>
    ---
    arch/x86/kernel/smpboot.c | 9 +++++++++
    1 files changed, 9 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
    index fd019d7..3fab55b 100644
    --- a/arch/x86/kernel/smpboot.c
    +++ b/arch/x86/kernel/smpboot.c
    @@ -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);


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