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[Xen-devel] what the meaning of the per cpu variable cpu_core_mask and cpu_sibling_mask?

  • To: xen-devel@xxxxxxxxxxxxx
  • From: Demon King <kdmxen@xxxxxxxxx>
  • Date: Thu, 21 Mar 2013 17:53:28 +0800
  • Delivery-date: Thu, 21 Mar 2013 09:54:17 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>

I am a new comer of xen-devel. When I read the source code of sched_credit.c. I was confused by such codes below:

if ( cpumask_test_cpu(cpu, per_cpu(cpu_core_mask, nxt)) )
            /* We're on the same socket, so check the busy-ness of threads.
             * Migrate if # of idlers is less at all */
            ASSERT( cpumask_test_cpu(nxt, per_cpu(cpu_core_mask, cpu)) );
            migrate_factor = 1;
            cpumask_and(&cpu_idlers, &idlers, per_cpu(cpu_sibling_mask, cpu));
            cpumask_and(&nxt_idlers, &idlers, per_cpu(cpu_sibling_mask, nxt));

I don't know much about xen or linux. So I get confused in the per cpu variable: cpu_core_mask and cpu_sibling_mask
Is anyone willing to tell me? Thank you! And may I ask you where to get answers about this kind of question?
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