* strange cpu number from xm info
@ 2012-04-06 12:45 Zhigang Wang
2012-04-06 19:52 ` Jan Beulich
0 siblings, 1 reply; 7+ messages in thread
From: Zhigang Wang @ 2012-04-06 12:45 UTC (permalink / raw)
To: xen-devel
Hi,
I see this output from xm info:
# xm info
...
release : 2.6.32.21-45.6xen
version : #1 SMP Wed Feb 29 23:42:59 EST 2012
machine : x86_64
nr_cpus : 8
nr_nodes : 1
cores_per_socket : 4
threads_per_core : 1
cpu_mhz : 2826
I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
But the above output is not.
Could anyone explain it a little?
Thanks,
Zhigang
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-04-06 12:45 strange cpu number from xm info Zhigang Wang
@ 2012-04-06 19:52 ` Jan Beulich
2012-04-06 20:01 ` Zhigang Wang
0 siblings, 1 reply; 7+ messages in thread
From: Jan Beulich @ 2012-04-06 19:52 UTC (permalink / raw)
To: zhigang.x.wang; +Cc: xen-devel
>>> Zhigang Wang <zhigang.x.wang@oracle.com> 04/06/12 2:45 PM >>>
>nr_cpus : 8
>nr_nodes : 1
>cores_per_socket : 4
>threads_per_core : 1
>
>I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * threads_per_core
Jan
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-04-06 19:52 ` Jan Beulich
@ 2012-04-06 20:01 ` Zhigang Wang
2012-04-06 21:09 ` Dan Magenheimer
2012-04-07 7:39 ` Ian Campbell
0 siblings, 2 replies; 7+ messages in thread
From: Zhigang Wang @ 2012-04-06 20:01 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel
On 04/06/2012 03:52 PM, Jan Beulich wrote:
>>>> Zhigang Wang <zhigang.x.wang@oracle.com> 04/06/12 2:45 PM >>>
>> nr_cpus : 8
>> nr_nodes : 1
>> cores_per_socket : 4
>> threads_per_core : 1
>>
>> I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
> nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * threads_per_core
It seems on xm/xl info we don't show how many sockets_per_node. Can we do that
in the future?
It seems this machine has: sockets_per_node = 2.
Thanks very much Jan.
Zhigang
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-04-06 20:01 ` Zhigang Wang
@ 2012-04-06 21:09 ` Dan Magenheimer
2012-04-07 7:39 ` Ian Campbell
1 sibling, 0 replies; 7+ messages in thread
From: Dan Magenheimer @ 2012-04-06 21:09 UTC (permalink / raw)
To: Zhigang Wang, Jan Beulich; +Cc: xen-devel
> From: Zhigang Wang
> Sent: Friday, April 06, 2012 2:01 PM
> To: Jan Beulich
> Cc: xen-devel@lists.xen.org
> Subject: Re: [Xen-devel] strange cpu number from xm info
>
> On 04/06/2012 03:52 PM, Jan Beulich wrote:
> >>>> Zhigang Wang <zhigang.x.wang@oracle.com> 04/06/12 2:45 PM >>>
> >> nr_cpus : 8
> >> nr_nodes : 1
> >> cores_per_socket : 4
> >> threads_per_core : 1
> >>
> >> I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
> > nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * threads_per_core
> It seems on xm/xl info we don't show how many sockets_per_node. Can we do that
> in the future?
>
> It seems this machine has: sockets_per_node = 2.
>
> Thanks very much Jan.
>
> Zhigang
Hi Zhigang --
Unfortunately, the world of CPUs is getting more complicated
and can no longer be described so simply. See for example:
http://lists.xen.org/archives/html/xen-devel/2009-11/msg00885.html
On a Friday afternoon, this makes my head hurt...
Dan
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-04-06 20:01 ` Zhigang Wang
2012-04-06 21:09 ` Dan Magenheimer
@ 2012-04-07 7:39 ` Ian Campbell
2012-05-31 13:15 ` Zhigang Wang
1 sibling, 1 reply; 7+ messages in thread
From: Ian Campbell @ 2012-04-07 7:39 UTC (permalink / raw)
To: Zhigang Wang; +Cc: Jan Beulich, xen-devel
On Fri, 2012-04-06 at 21:01 +0100, Zhigang Wang wrote:
> On 04/06/2012 03:52 PM, Jan Beulich wrote:
> >>>> Zhigang Wang <zhigang.x.wang@oracle.com> 04/06/12 2:45 PM >>>
> >> nr_cpus : 8
> >> nr_nodes : 1
> >> cores_per_socket : 4
> >> threads_per_core : 1
> >>
> >> I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
> > nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * threads_per_core
> It seems on xm/xl info we don't show how many sockets_per_node. Can we do that
> in the future?
We can and should. Are you able to send a patch for xl at least?
Thanks,
Ian.
> It seems this machine has: sockets_per_node = 2.
>
> Thanks very much Jan.
>
> Zhigang
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-04-07 7:39 ` Ian Campbell
@ 2012-05-31 13:15 ` Zhigang Wang
2012-05-31 14:00 ` Dario Faggioli
0 siblings, 1 reply; 7+ messages in thread
From: Zhigang Wang @ 2012-05-31 13:15 UTC (permalink / raw)
To: Ian Campbell; +Cc: Dan Magenheimer, Jan Beulich, xen-devel
On 04/07/2012 03:39 AM, Ian Campbell wrote:
> On Fri, 2012-04-06 at 21:01 +0100, Zhigang Wang wrote:
>> On 04/06/2012 03:52 PM, Jan Beulich wrote:
>>>>>> Zhigang Wang <zhigang.x.wang@oracle.com> 04/06/12 2:45 PM >>>
>>>> nr_cpus : 8
>>>> nr_nodes : 1
>>>> cores_per_socket : 4
>>>> threads_per_core : 1
>>>>
>>>> I thought nr_cpus = nr_nodes * cores_per_socket * threads_per_core
>>> nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * threads_per_core
>> It seems on xm/xl info we don't show how many sockets_per_node. Can we do that
>> in the future?
> We can and should. Are you able to send a patch for xl at least?
>
>
Here is another case:
# xm info
...
nr_cpus : 48
nr_nodes : 8
cores_per_socket : 12
threads_per_core : 1
This HP BL685 G7 (4 socket x 12 cores).
Actually sockets_per_node = 0.5. Xen calculates it correctly.
Should we should s 0.5 for sockets_per_node? Or just ignore sockets_per_node?
Thanks,
Zhigang
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: strange cpu number from xm info
2012-05-31 13:15 ` Zhigang Wang
@ 2012-05-31 14:00 ` Dario Faggioli
0 siblings, 0 replies; 7+ messages in thread
From: Dario Faggioli @ 2012-05-31 14:00 UTC (permalink / raw)
To: Zhigang Wang; +Cc: Dan Magenheimer, Ian Campbell, Jan Beulich, xen-devel
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On Thu, 2012-05-31 at 09:15 -0400, Zhigang Wang wrote:
> > We can and should. Are you able to send a patch for xl at least?
> >
> >
> Here is another case:
>
> # xm info
> ...
> nr_cpus : 48
> nr_nodes : 8
> cores_per_socket : 12
> threads_per_core : 1
>
> This HP BL685 G7 (4 socket x 12 cores).
>
> Actually sockets_per_node = 0.5. Xen calculates it correctly.
>
> Should we should s 0.5 for sockets_per_node? Or just ignore sockets_per_node?
>
I looked a bit into this and found out there has been some discussion
already on why such a "counter" (sockets_per_node) has been removed and
shouldn't be reintroduced, and those archs yielding fractional numbers
for it seem to be right that cause:
http://old-list-archives.xen.org/xen-changelog/2010-04/msg00074.html
http://old-list-archives.xen.org/archives/html/xen-devel/2010-02/msg00005.html
Not sure what TheRightThing is here, just wanted to point these out...
Regards,
Dario
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
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2012-04-06 12:45 strange cpu number from xm info Zhigang Wang
2012-04-06 19:52 ` Jan Beulich
2012-04-06 20:01 ` Zhigang Wang
2012-04-06 21:09 ` Dan Magenheimer
2012-04-07 7:39 ` Ian Campbell
2012-05-31 13:15 ` Zhigang Wang
2012-05-31 14:00 ` Dario Faggioli
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