On Sun 15-03-20 14:20:05, Cristopher Lameter wrote: > On Wed, 11 Mar 2020, Srikar Dronamraju wrote: > > > Currently Linux kernel with CONFIG_NUMA on a system with multiple > > possible nodes, marks node 0 as online at boot. However in practice, > > there are systems which have node 0 as memoryless and cpuless. > > Would it not be better and simpler to require that node 0 always has > memory (and processors)? A mininum operational set? I do not think you can simply ignore the reality. I cannot say that I am a fan of memoryless/cpuless numa configurations but they are a sad reality of different LPAR configurations. We have to deal with them. Besides that I do not really see any strong technical arguments to lack a support for those crippled configurations. We do have zonelists that allow to do reasonable decisions on memoryless nodes. So no, I do not think that this is a viable approach. > We can dynamically number the nodes right? So just make sure that the > firmware properly creates memory on node 0? Are you suggesting that the OS would renumber NUMA nodes coming from FW just to satisfy node 0 existence? If yes then I believe this is really a bad idea because it would make HW/LPAR configuration matching to the resulting memory layout really hard to follow. -- Michal Hocko SUSE Labs
