[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Spurious "NUMA placement failed, performance might be affected" message on ARM
On ven, 2014-04-25 at 11:37 +0100, Ian Campbell wrote: > Hi Dario, > > When starting a guest on ARM I'm seeing (with no additional verbosity): > libxl: notice: libxl_numa.c:494:libxl__get_numa_candidate: NUMA > placement failed, performance might be affected > > Which is a bit strong for a non-NUMA system. > Indeed. > Is there some hypercall we need to stub out or return -ENOSYS from to > cause this function to decide that this is not a NUMA system? > > Does the same message occur on non-NUMA x86 systems? > The message is printed inside libxl__get_numa_candidate() if no suitable placement candidate is found. It does not happen on x86 non-NUMA boxes as what happens there is that there is only 1 node, so the set of possible combinations of nodes is made up of only one element, which is deemed to be the best possible solution very quickly. While I wonder why that does not happen on ARM, a sensible solution would be to bail earlier, if we find only one NUMA node exist, for whatever arch. Would that be ok? If yes, I can arrange a patch pretty easily, I think. For figuring out why the different behavior... Do you have the output of `xl info -n' on that box handy, by any chance? Regards, Dario -- <<This happens because I choose it to happen!>> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) Attachment:
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