Tyrel Datwyler <tyr...@linux.vnet.ibm.com> writes: > On 05/16/2019 12:17 PM, Nathan Lynch wrote: >> Tyrel Datwyler <tyr...@linux.ibm.com> writes: >>> The current dlpar_cpu_readd() takes in a cpu_id and uses that to look up >>> the cpus device_node so that we can get at the ibm,my-drc-index >>> property. The only user of cpu readd is an OF notifier call back. This >>> call back already has a reference to the device_node and therefore can >>> retrieve the drc_index from the device_node. >> >> dlpar_cpu_readd is a hack to try to change the CPU-node relationship at >> runtime without destabilizing the system. It doesn't accomplish that and >> it should just be removed (and I'm working on that). >> > > I will politely disagree. We've done exactly this from userspace for > years. My experience still suggests that memory affinity is the > problem area, and that the work to push this all into the kernel > originally was poorly tested.
Kernel implementation details aside, how do you change the cpu-node relationship at runtime without breaking NUMA-aware applications? Is this not a fundamental issue to address before adding code like this?
