* Michal Hocko <mhocko@xxxxxxxxxx> [2020-03-16 09:54:25]: > 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. > I agree with Michal, kernel should accept the reality and work with different Lpar configurations. > > 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 Michal, Vlastimil, Christoph and others, do you have any more comments, suggestions or any other feedback. If not, can you please add your reviewed-by, acked etc. -- Thanks and Regards Srikar Dronamraju
