Messages in this thread | | | Date | Wed, 23 Sep 2015 08:25:44 -0400 | From | Boris Ostrovsky <> | Subject | Re: [Xen-devel] [PATCH RFC] xen: if on Xen, "flatten" the scheduling domain hierarchy |
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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
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