Messages in this thread | | | From | Bjorn Helgaas <> | Subject | Re: [PATCH] remove empty node at boot time | Date | Tue, 11 Jul 2006 09:37:11 -0600 |
| |
On Tuesday 11 July 2006 00:55, KAMEZAWA Hiroyuki wrote: > On Mon, 10 Jul 2006 11:03:03 -0600 > Bjorn Helgaas <bjorn.helgaas@hp.com> wrote: > > > On Sunday 09 July 2006 23:19, KAMEZAWA Hiroyuki wrote: > > > Could you try this patch ? (against 2.6.18-rc1) > > > > Your patch does fix it. But I'm worried about removing > > empty nodes at boot-time. I want to support the following > > scenario: > > > > node 0: 1 enabled CPU, 3 disabled CPUs, no local memory > > node 1: 4 disabled CPUs, no local memory > > node 2: no CPUs, big interleaved memory across nodes 0 & 1 > > > > At run-time, I'd like to be able to enable any or all of the > > 7 disabled CPUs. If you remove the "empty" node 1 at boot-time, > > it sounds like I won't be able to enable its CPUs later. > > > > Hmm.. in my understanding, all structures for *possible* cpus are allocated > at boot time. Then, only problem seems that a cpu is tied to > not-exisiting-node at boot time. > (see arch/ia64/kernel/numa.c, build_cpu_to_node_map()) > > ==== > void __init build_cpu_to_node_map(void) > { > int cpu, i, node; > > for(node=0; node < MAX_NUMNODES; node++) > cpus_clear(node_to_cpu_mask[node]); > > for(cpu = 0; cpu < NR_CPUS; ++cpu) { > node = -1; > for (i = 0; i < NR_CPUS; ++i) > if (cpu_physical_id(cpu) == node_cpuid[i].phys_id) { > node = node_cpuid[i].nid; > break; > } > cpu_to_node_map[cpu] = (node >= 0) ? node : 0; > if (node >= 0) > cpu_set(cpu, node_to_cpu_mask[node]); > } > } > ===== > > Then what we have to do here are > 1. remap cpu to the first existing node at hot-add event > or > 2. implement node-hot-add triggered by cpu-hot-add. > Because we already have implemented node-hot-add triggered by memory-hotadd > we can do it by small effort.
I haven't paid much attention to the memory/cpu/node hotplug stuff, but (2) sounds reasonable.
> I think above will work for your environment. > do you have any idea other than "don't remove empty node at boot time" ? > or reserve empty node is the best way ? - 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/
| |