Odd performance results

From	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Odd performance results
Date	2016-07-10 06:30 +0200
Message-ID	<rTexs-4cA-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hello!

So I ran a quick benchmark which showed stair-step results.  I immediately
thought "Ah, this is due to CPU 0 and 1, 2 and 3, 4 and 5, and 6 and 7
being threads in a core."  Then I thought "Wait, this is an x86!"
Then I dumped out cpu*/topology/thread_siblings_list, getting the following:

	cpu0/topology/thread_siblings_list: 0-1
	cpu1/topology/thread_siblings_list: 0-1
	cpu2/topology/thread_siblings_list: 2-3
	cpu3/topology/thread_siblings_list: 2-3
	cpu4/topology/thread_siblings_list: 4-5
	cpu5/topology/thread_siblings_list: 4-5
	cpu6/topology/thread_siblings_list: 6-7
	cpu7/topology/thread_siblings_list: 6-7

Is this now expected behavior or a fluke of my particular laptop?  Here is
hoping for expected behavior, as it makes NUMA locality the default for
a great many workloads.

Enlightenment?

							Thanx, Paul

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Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-10 06:30 +0200
  Re: Odd performance results Peter Zijlstra <peterz@infradead.org> - 2016-07-10 07:20 +0200
    Re: Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-10 16:50 +0200
      Re: Odd performance results Peter Zijlstra <peterz@infradead.org> - 2016-07-12 17:00 +0200
        Re: Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-12 17:10 +0200
          Re: Odd performance results "H. Peter Anvin" <hpa@zytor.com> - 2016-07-12 20:00 +0200
            Re: Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-12 20:30 +0200
            Re: Odd performance results Peter Zijlstra <peterz@infradead.org> - 2016-07-12 21:00 +0200
              Re: [CRM114spam]: Re: Odd performance results "Dr. David Alan Gilbert" <dave@treblig.org> - 2016-07-12 21:40 +0200
                Re: [CRM114spam]: Re: Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-12 22:10 +0200
                Re: [CRM114spam]: Re: Odd performance results Ingo Molnar <mingo@kernel.org> - 2016-07-13 09:30 +0200
              Re: Odd performance results Ingo Molnar <mingo@kernel.org> - 2016-07-13 09:20 +0200
                Re: Odd performance results Henrique de Moraes Holschuh <hmh@hmh.eng.br> - 2016-07-13 14:40 +0200
                Re: Odd performance results Peter Zijlstra <peterz@infradead.org> - 2016-07-13 14:40 +0200
                Re: Odd performance results "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 16:10 +0200

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