On 24.06.2014 [09:33:48 +0200], Igor Mammedov wrote: > On Mon, 23 Jun 2014 12:33:10 -0700 > Nishanth Aravamudan <n...@linux.vnet.ibm.com> wrote: > > > Add a present field to NodeInfo which indicates if a given nodeid was > > present on the command-line or not. Current code relies on a memory > > value being passed for a node to indicate presence, which is > > insufficient in the presence of memoryless nodes or sparse numbering. > > Adjust the iteration of various NUMA loops to use the maximum known NUMA > > ID rather than the number of NUMA nodes. > Why would you need sparse numbering?
We already see this in practice under PowerVM on ppc. This would allow qemu/KVM to emulate the same behaviors (which often lead to bugs/testing of underused code-paths in the kernel). Also, sparse numbering is explicitly allowed by qemu already but doesn't work at all as expected, at least to me. That is, if I specify various node IDs, the nodes are allocated linearly in qemu and the NUMA node IDs in Linux don't correspond to the command-line. Further, the location of CPUs/memory doesn't correspond to the nodes requested by the user. > What task exactly are you trying to solve? I would like to be able to leverage qemu's command-line to reproduce the NUMA topology seen under PowerVM. I'll send v3 with a better changelog and a few changes from Hu Tao. Thanks, Nish
