Messages in this thread | | | Date | Tue, 23 Apr 2013 10:24:36 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [Bug fix PATCH v2] numa, cpu hotplug: Change links of CPU and node when changing node number by onlining CPU |
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2013/04/23 9:34, Andrew Morton wrote: > On Tue, 23 Apr 2013 09:04:46 +0900 Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> wrote: > >> 2013/04/23 7:35, Andrew Morton wrote: >>> On Fri, 19 Apr 2013 14:23:23 +0900 Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> wrote: >>> >>>> When booting x86 system contains memoryless node, node numbers of CPUs >>>> on memoryless node were changed to nearest online node number by >>>> init_cpu_to_node() because the node is not online. >>>> >>>> ... >>>> >>>> If we hot add memory to memoryless node and offine/online all CPUs on >>>> the node, node numbers of these CPUs are changed to correct node numbers >>>> by srat_detect_node() because the node become online. >>> >>> OK, here's a dumb question. >>> >>> At boot time the CPUs are assigned to the "nearest online node" rather >>> than to their real memoryless node. The patch arranges for those CPUs >>> to still be assigned to the "nearest online node" _after_ some memory >>> is hot-added to their real node. Correct? >> >> Yes. For changing node number of CPUs safely, we should offline CPUs. >> >>> >>> Would it not be better to fix this by assigning those CPUs to their real, >>> memoryless node right at the initial boot? Or is there something in >>> the kernel which makes cpus-on-a-memoryless-node not work correctly? >>> >> >> I think assigning CPUs to real node is better. But current Linux's node >> strongly depend on memory. Thus if we just create cpus-on-a-memoryless-node, >> the kernel cannot work correctly. > > hm, why. I'd have thought that if we tell the kernel something like > "this node has one zone, the size of which is zero bytes" then a > surprising amount of the existing code will Just Work. > > What goes wrong?
Sorry I forgot detailed issue. When I saw following issue, I tried to fix it and found that current Linux's node strongly depend on memory. https://lkml.org/lkml/2012/9/12/20
I'll try to fix it again.
Thanks, Yasuaki Ishimatsu
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