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Date:      Tue, 27 Aug 2013 13:05:05 +0800
From:      David Xu <davidxu@freebsd.org>
To:        freebsd-threads@freebsd.org
Subject:   Re: About CPU cores numbering an processor affinity
Message-ID:  <521C3381.3030207@freebsd.org>
In-Reply-To: <970B3263-4689-4F8A-B012-DA88A1266F45@gmail.com>
References:  <1D21F5BC-63CD-4B33-9286-6687E62FDB15@gmail.com> <970B3263-4689-4F8A-B012-DA88A1266F45@gmail.com>

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sysctl kern.sched.topology_spec ?


On 2013/08/26 21:33, Dmitry Sivachenko wrote:
> Nobody answered on -hackers, I try to ask there.
>
> Begin forwarded message:
>
>> From: Dmitry Sivachenko <trtrmitya@gmail.com>
>> Subject: About CPU cores numbering an processor affinity
>> Date: 23 августа 2013 г., 17:23:51 GMT+04:00
>> To: hackers@freebsd.org
>>
>> Hello!
>>
>> I am using FreeBSD-9-STABLE on the following hardware:
>>
>> FreeBSD/SMP: Multiprocessor System Detected: 24 CPUs
>> FreeBSD/SMP: 2 package(s) x 6 core(s) x 2 SMT threads
>>
>> So I have 2 physical CPUs with 6 core each.
>>
>> # cpuset -g
>> pid -1 mask: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23
>>
>>
>> So each of 24 cores are numbered 0..23.
>>
>> 1) In what particular order are these cores numbered?  Can I assume that 0..11 correspond to 1st physical CPU and 12..23 to second?  How SMT threads are numbered within each core?
>>
>> 2) This machine has Intel network adapter (em driver).  I want to pin network interrupt thread and proxy software to the same processor so they share at least L2 or L3 cache.  How can I do this?  From the one hand, I see the following processes:
>>
>>    11 root         -92    -     0K   720K WAIT   19 146:38  0.00% intr{irq260: em1:rx 0}
>>    11 root         -92    -     0K   720K WAIT   19  15:11  0.00% intr{irq261: em1:tx 0}
>>
>>  From the other hand, the following processes seems to be unrelated to network but they share same PID:
>>    11 root         -60    -     0K   720K WAIT    1 131:20  0.00% intr{swi4: clock}
>>    11 root         -88    -     0K   720K WAIT   17  40:03  0.00% intr{irq263: ahci0}
>>    11 root         -72    -     0K   720K WAIT   22  17:35  0.00% intr{swi1: netisr 0}
>>    11 root         -88    -     0K   720K WAIT    3   3:08  0.00% intr{irq256: mfi0}
>>
>> Should I use "-x" option of cpuset for that purpose (to bind irq 260 and 261 in my example)?
>>
>> Thanks in advance!
>>
>
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