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authorMike Travis <travis@sgi.com>2007-10-17 12:04:39 -0400
committerThomas Gleixner <tglx@inhelltoy.tec.linutronix.de>2007-10-17 14:16:37 -0400
commit98c9e27a56a2d9f9148992b0b9a9a36760ea4eb9 (patch)
tree1f454309248477977d6654ee57480ef18140dce6 /arch/x86/mm/srat_64.c
parent6b556ffc4b8fc71445156bcdd02a16a364a36356 (diff)
x86: fix cpu_to_node references
In x86_64 and i386 architectures most arrays that are sized using NR_CPUS lay in local memory on node 0. Not only will most (99%?) of the systems not use all the slots in these arrays, particularly when NR_CPUS is increased to accommodate future very high cpu count systems, but a number of cache lines are passed unnecessarily on the system bus when these arrays are referenced by cpus on other nodes. Typically, the values in these arrays are referenced by the cpu accessing it's own values, though when passing IPI interrupts, the cpu does access the data relevant to the targeted cpu/node. Of course, if the referencing cpu is not on node 0, then the reference will still require cross node exchanges of cache lines. A common use of this is for an interrupt service routine to pass the interrupt to other cpus local to that node. Ideally, all the elements in these arrays should be moved to the per_cpu data area. In some cases (such as x86_cpu_to_apicid) the array is referenced before the per_cpu data areas are setup. In this case, a static array is declared in the __initdata area and initialized by the booting cpu (BSP). The values are then moved to the per_cpu area after it is initialized and the original static array is freed with the rest of the __initdata. This patch: Fix four instances where cpu_to_node is referenced by array instead of via the cpu_to_node macro. This is preparation to moving it to the per_cpu data area. Signed-off-by: Mike Travis <travis@sgi.com> Cc: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/mm/srat_64.c')
-rw-r--r--arch/x86/mm/srat_64.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/mm/srat_64.c b/arch/x86/mm/srat_64.c
index acdf03e19146..56089ccc3949 100644
--- a/arch/x86/mm/srat_64.c
+++ b/arch/x86/mm/srat_64.c
@@ -431,9 +431,9 @@ int __init acpi_scan_nodes(unsigned long start, unsigned long end)
431 setup_node_bootmem(i, nodes[i].start, nodes[i].end); 431 setup_node_bootmem(i, nodes[i].start, nodes[i].end);
432 432
433 for (i = 0; i < NR_CPUS; i++) { 433 for (i = 0; i < NR_CPUS; i++) {
434 if (cpu_to_node[i] == NUMA_NO_NODE) 434 if (cpu_to_node(i) == NUMA_NO_NODE)
435 continue; 435 continue;
436 if (!node_isset(cpu_to_node[i], node_possible_map)) 436 if (!node_isset(cpu_to_node(i), node_possible_map))
437 numa_set_node(i, NUMA_NO_NODE); 437 numa_set_node(i, NUMA_NO_NODE);
438 } 438 }
439 numa_init_array(); 439 numa_init_array();