* David Hildenbrand <david@xxxxxxxxxx> [2020-05-12 09:49:05]: > On 11.05.20 19:47, Srikar Dronamraju wrote: > > * David Hildenbrand <david@xxxxxxxxxx> [2020-05-08 15:42:12]: > > > > > > [root@localhost ~]# cat /sys/devices/system/node/online > > 0 > > [root@localhost ~]# cat /sys/devices/system/node/possible > > 0-1 > > > > Even without my patch, both the combinations, I am still unable to see a > > cpuless, memoryless node being online. And the interesting part being even > > Yeah, I think on x86, all memory-less and cpu-less nodes are offline as > default. Especially when hotunplugging cpus/memory, we set them offline > as well. I also came to the same conclusion that we may not have a cpuless,memoryless node on x86. > > But as Michal mentioned, the node handling code is complicated and > differs between various architectures. > I do agree that node handling code differs across various architectures and quite complicated. > > if I mark node 0 as cpuless,memoryless and node 1 as actual node, the system > > somewhere marks node 0 as the actual node. > > Is the kernel maybe mapping PXM 1 to node 0 in that case, because it > always requires node 0 to be online/contain memory? Would be interesting > what happens if you hotplug a DIMM to (QEMU )node 0 - if PXM 0 will be > mapped to node 1 then as well. > Satheesh Rajendra had tried with cpu hotplug on a similar setup and we found that it crashes the x86 system. reference: https://bugzilla.kernel.org/show_bug.cgi?id=202187 Even if we were able to hotplug 1 DIMM memory into node 1, that would no more be a memoryless node. -- Thanks and Regards Srikar Dronamraju
