lkml.org 
[lkml]   [2015]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Xen-devel] [PATCH RFC] xen: if on Xen, "flatten" the scheduling domain hierarchy
On 09/23/2015 03:35 AM, Juergen Gross wrote:
>
> Depends on the hardware. On some AMD processors one socket covers
> multiple NUMA nodes. This is the critical case. set_sched_topology()
> will be called on those machines possibly multiple times when bringing
> up additional cpus.
>
>> I'm asking because trying this out, right now, is not straightforward,
>> as PV vNUMA, even with Wei's Linux patches and with either yours or
>> mine one, still incurs in the CPUID issue... I'll try that ASAP, but
>> there are a couple of things I've got to finish for the next few days.
>>
>>> One of NUMA and Xen will win and
>>> overwrite the other's settings.
>>>
>> Not sure what this means, but as I said, I'll try.
>
> Make sure to use the correct hardware (I'm pretty sure this should be
> the AMD "Magny-Cours" [1]).
>
>
> Juergen
>
> [1]:
> http://developer.amd.com/resources/documentation-articles/articles-whitepapers/introduction-to-magny-cours/
>


There are few family 0x10 and 0x15 processors that are like that. You
can see whether you have such a system by comparing number of NUMA nodes
with number of physical IDs, e.g.:

[root@ovs106 ~]# numactl --hardware |grep available
available: 4 nodes (0-3)
[root@ovs106 ~]# grep "physical id" /proc/cpuinfo | uniq
physical id : 0
physical id : 1
[root@ovs106 ~]#


-boris


\
 
 \ /
  Last update: 2015-09-23 14:41    [W:0.069 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site