linux-kernel - Re: Odd performance results

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Message-ID: <7DF218CD-22F6-4E46-A628-2138AEA3A161@infradead.org>
Date:	Sun, 10 Jul 2016 07:17:19 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	paulmck@...ux.vnet.ibm.com, hpa@...or.com, tglx@...utronix.de,
	mingo@...e.hu, ak@...ux.intel.com
CC:	linux-kernel@...r.kernel.org
Subject: Re: Odd performance results



On 10 July 2016 06:26:39 CEST, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
>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


I'm guessing this is an AMD bulldozer like machine?
-- 
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