On Thu, 2015-02-07 at 23:02:02 UTC, Nishanth Aravamudan wrote: > Much like on x86, now that powerpc is using USE_PERCPU_NUMA_NODE_ID, we > have an ordering issue during boot with early calls to cpu_to_node().
"now that .." implies we changed something and broke this. What commit was it that changed the behaviour? > The value returned by those calls now depend on the per-cpu area being > setup, but that is not guaranteed to be the case during boot. Instead, > we need to add an early_cpu_to_node() which doesn't use the per-CPU area > and call that from certain spots that are known to invoke cpu_to_node() > before the per-CPU areas are not configured. > > On an example 2-node NUMA system with the following topology: > > available: 2 nodes (0-1) > node 0 cpus: 0 1 2 3 > node 0 size: 2029 MB > node 0 free: 1753 MB > node 1 cpus: 4 5 6 7 > node 1 size: 2045 MB > node 1 free: 1945 MB > node distances: > node 0 1 > 0: 10 40 > 1: 40 10 > > we currently emit at boot: > > [ 0.000000] pcpu-alloc: [0] 0 1 2 3 [0] 4 5 6 7 > > After this commit, we correctly emit: > > [ 0.000000] pcpu-alloc: [0] 0 1 2 3 [1] 4 5 6 7 So it looks fairly sane, and I guess it's a bug fix. But I'm a bit reluctant to put it in straight away without some time in next. It looks like the symptom is that the per-cpu areas are all allocated on node 0, is that all that goes wrong? cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
