Hello, On Mon, Mar 02, 2015 at 05:41:05PM +0900, Kamezawa Hiroyuki wrote: > Let me start from explaining current behavior. > > - cpu-id is determined when a new processor(lapicid/x2apicid) is founded. > cpu-id<->nodeid relationship is _not_ recorded.
Is this something from the firmware side or is it just that we aren't maintaining the association right now? > - node-id is determined when a new pxm(firmware info) is founded. > pxm<->nodeid relationship is recorded. > > By this, there are 2 cases of cpu<->nodeid change. > > Case A) In x86, cpus on memory-less nodes are all tied to existing > nodes(round robin). > At memory-hotadd happens and a new node comes, cpus are moved to a newly > added node > based on pxm. Ah, okay, so the firmware doesn't provide proximity information at all for memory-less nodes so we end up putting all of them somewhere random and when memory is added to one of the memory-less nodes, the mapping information changes? Am I understanding it correctly? If so, it's super weird tho. Why wouldn't there be proximity information for a memless node? Not having memory doesn't mean it's at the same distance from all existing nodes. > Case B) Adding a node after removing another node, if pxm of them were > different from > each other, cpu<->node relatiionship changes. I don't get this either. Does proximity relationship actually change? Or is it that we're assigning different IDs to the same thing? Isn't proximity pretty much hardwired to how the system is architected to begin with? > I personally thinks proper fix is building persistent cpu-id <-> lapicid > relationship as > pxm does rather than creating band-aid. Oh if this is possible, I agree that's the right direction too. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
