From: Andi Kleen <ak@suse.de>
Apply this handy patch and boot with numa=fake=4 (or how many nodes you
want, 8 max right now).
There is a minor issue with the hash function, which can make the last node
be bigger than the others. Is probably fixable if it should be a problem.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
/dev/null | 0
25-akpm/arch/x86_64/mm/numa.c | 55 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 54 insertions(+), 1 deletion(-)
diff -puN arch/x86_64/mm/numa.c~x86_64-numa-emulation arch/x86_64/mm/numa.c
--- 25/arch/x86_64/mm/numa.c~x86_64-numa-emulation 2004-08-04 22:13:47.710023216 -0700
+++ 25-akpm/arch/x86_64/mm/numa.c 2004-08-04 22:13:47.717022152 -0700
@@ -163,10 +163,58 @@ void __init numa_init_array(void)
set_bit(0, &node_to_cpumask[cpu_to_node(0)]);
}
+int numa_fake __initdata = 0;
+
+/* Numa emulation */
+static int numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
+{
+ int i;
+ struct node nodes[MAXNODE];
+ unsigned long sz = ((end_pfn - start_pfn)<<PAGE_SHIFT) / numa_fake;
+
+ /* Kludge needed for the hash function */
+ if (hweight64(sz) > 1) {
+ unsigned long x = 1;
+ while ((x << 1) < sz)
+ x <<= 1;
+ if (x < sz/2)
+ printk("Numa emulation unbalanced. Complain to maintainer\n");
+ sz = x;
+ }
+
+ memset(&nodes,0,sizeof(nodes));
+ for (i = 0; i < numa_fake; i++) {
+ nodes[i].start = (start_pfn<<PAGE_SHIFT) + i*sz;
+ if (i == numa_fake-1)
+ sz = (end_pfn<<PAGE_SHIFT) - nodes[i].start;
+ nodes[i].end = nodes[i].start + sz;
+ if (i != numa_fake-1)
+ nodes[i].end--;
+ printk(KERN_INFO "Faking node %d at %016Lx-%016Lx (%LuMB)\n",
+ i,
+ nodes[i].start, nodes[i].end,
+ (nodes[i].end - nodes[i].start) >> 20);
+ }
+ numnodes = numa_fake;
+ memnode_shift = compute_hash_shift(nodes);
+ if (memnode_shift < 0) {
+ memnode_shift = 0;
+ printk(KERN_ERR "No NUMA hash function found. Emulation disabled.\n");
+ return -1;
+ }
+ for (i = 0; i < numa_fake; i++)
+ setup_node_bootmem(i, nodes[i].start, nodes[i].end);
+ numa_init_array();
+ return 0;
+}
+
void __init numa_initmem_init(unsigned long start_pfn, unsigned long end_pfn)
{
int i;
+ if (numa_fake && !numa_emulation(start_pfn, end_pfn))
+ return;
+
#ifdef CONFIG_K8_NUMA
if (!numa_off && !k8_scan_nodes(start_pfn<<PAGE_SHIFT, end_pfn<<PAGE_SHIFT))
return;
@@ -215,8 +263,13 @@ void __init paging_init(void)
/* [numa=off] */
__init int numa_setup(char *opt)
{
- if (!strncmp(opt,"off",3))
+ if (!strcmp(opt,"off"))
numa_off = 1;
+ if(!strncmp(opt, "fake=", 5)) {
+ numa_fake = simple_strtoul(opt+5,NULL,0); ;
+ if (numa_fake >= MAX_NUMNODES)
+ numa_fake = MAX_NUMNODES;
+ }
return 1;
}
diff -L arch/x86_64/mm/numa.c-EMU -puN /dev/null /dev/null
_