At 08/20/2012 02:21 PM, wujianguo Wrote:
> From: Jianguo Wu <wujian...@huawei.com>
>
> Hi all,
> When doing memory-hot-plug, We found node distance is wrong after
> offline
> a node in IA64 platform. For example system has 4 nodes:
> node distances:
> node 0 1 2 3
> 0: 10 21 21 32
> 1: 21 10 32 21
> 2: 21 32 10 21
> 3: 32 21 21 10
>
> linux-drf:/sys/devices/system/node/node0 # cat distance
> 10 21 21 32
> linux-drf:/sys/devices/system/node/node1 # cat distance
> 21 10 32 21
>
> After offline node2:
> linux-drf:/sys/devices/system/node/node0 # cat distance
> 10 21 32
> linux-drf:/sys/devices/system/node/node1 # cat distance
> 32 21 32 --------->expected value is: 21 10 21
>
> In arch IA, we have following definition:
> extern u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES];
> #define node_distance(from,to) (numa_slit[(from) * num_online_nodes() + (to)])
>
> node distance is setup as following:
> acpi_numa_arch_fixup()
> {
> ...
> memset(numa_slit, -1, sizeof(numa_slit));
> for (i = 0; i < slit_table->locality_count; i++) {
> if (!pxm_bit_test(i))
> continue;
> node_from = pxm_to_node(i);
> for (j = 0; j < slit_table->locality_count; j++) {
> if (!pxm_bit_test(j))
> continue;
> node_to = pxm_to_node(j);
> node_distance(node_from, node_to) =
> slit_table->entry[i * slit_table->locality_count +
> j];
> }
> }
> ...
> }
> num_online_nodes() is a variable value, during system boot the return
> vale is 4,
> but after offline node2, the return value is 3, so we read a wrong node
> distance value.
> This patch is trying to fix this bug.
>
> Signed-off-by: Jianguo Wu <wujian...@huawei.com>
> ---
> arch/ia64/include/asm/numa.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/ia64/include/asm/numa.h b/arch/ia64/include/asm/numa.h
> index 6a8a27c..2e27ef1 100644
> --- a/arch/ia64/include/asm/numa.h
> +++ b/arch/ia64/include/asm/numa.h
> @@ -59,7 +59,7 @@ extern struct node_cpuid_s node_cpuid[NR_CPUS];
> */
>
> extern u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES];
> -#define node_distance(from,to) (numa_slit[(from) * num_online_nodes() +
> (to)])
> +#define node_distance(from,to) (numa_slit[(from) * MAX_NUMNODES + (to)])
Hmm, MAX_NUMNODES is too large. I think num_possible_nodes() is better.
Thanks
Wen Congyang
>
> extern int paddr_to_nid(unsigned long paddr);
>
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