Messages in this thread | | | Subject | Re: Externalize SLIT table | From | Matthew Dobson <> | Date | Tue, 09 Nov 2004 15:58:44 -0800 |
| |
On Tue, 2004-11-09 at 12:34, Mark Goodwin wrote: > On Tue, 9 Nov 2004, Matthew Dobson wrote: > > ... > > I don't think we should export the *exact same* node distance information > > through the CPUs, though. > > We should still export cpu distances though because the distance between > cpus on the same node may not be equal. e.g. consider a node with multiple > cpu sockets, each socket with a hyperthreaded (or dual core) cpu.
Well, I'm not sure that just because a CPU has two hyperthread units in the same core that those HT units have a different distance or latency to memory...? The fact that it is a HT unit and not a physical core has implications to the scheduler, but I thought that the 2 siblings looked identical to userspace, no? If 2 CPUs in the same node are on the same bus, then in all likelihood they have the same "distance".
> Once again however, it depends on the definition of distance. For nodes, > we've established it's the ACPI SLIT (relative distance to memory). For > cpus, should it be distance to memory? Distance to cache? Registers? Or > what? > > -- Mark
That's the real issue. We need to agree upon a meaningful definition of CPU-to-CPU "distance". As Jesse mentioned in a follow-up, we can all agree on what Node-to-Node "distance" means, but there doesn't appear to be much consensus on what CPU "distance" means.
-Matt
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |