Re: [PATCH 02/10] x86: Change size of node ids from u8 to u16 V3

Mike Travis
2008-01-16T18:10:29Z

Eric Dumazet wrote:
> On Wed, 16 Jan 2008 09:09:04 -0800
> travis@sgi.com wrote:
>
>> Change the size of node ids from 8 bits to 16 bits to
>> accomodate more than 256 nodes.
>>
>> Signed-off-by: Mike Travis <travis@sgi.com>
>> Reviewed-by: Christoph Lameter <clameter@sgi.com>
>> ---
>> V1->V2:
>> - changed pxm_to_node_map to u16
>> - changed memnode map entries to u16
>> V2->V3:
>> - changed memnode.embedded_map from [64-16] to [64-8]
>> (and size comment to 128 bytes)
>> ---
>> arch/x86/mm/numa_64.c | 9 ++++++---
>> arch/x86/mm/srat_64.c | 2 +-
>> drivers/acpi/numa.c | 2 +-
>> include/asm-x86/mmzone_64.h | 6 +++---
>> include/asm-x86/numa_64.h | 4 ++--
>> include/asm-x86/topology.h | 2 +-
>> 6 files changed, 14 insertions(+), 11 deletions(-)
>
> I know new typedefs are not welcome, but in this case, it could be nice
> to define a fundamental type node_t (like pte_t, pmd_t, pgd_t, ...).
>
> Clean NUMA code deserves it.
>
> #if MAX_NUMNODES > 256
> typedef u16 node_t;
> #else
> typedef u8 node_t;
> #endif
>

Funny, I had this in originally and someone suggested that it was
superfluous. ;-) But I agree, though I had called it numanode_t.
Even a cpu_t for size of the cpu index could be useful.

I'll wait for other opinions.

> In 2016, we can add u32 for MAX_NUMNODES > 65536

Probably 2010 is closer... ;-)

>
> Another point: you want this change, sorry if my previous mail was not detailed enough :
>
> --- a/arch/x86/mm/numa_64.c
> +++ b/arch/x86/mm/numa_64.c
> @@ -78,7 +78,7 @@ static int __init allocate_cachealigned_memnodemap(void)
> unsigned long pad, pad_addr;
>
> memnodemap = memnode.embedded_map;
> - if (memnodemapsize <= 48)
> + if (memnodemapsize <= ARRAY_SIZE(memnode.embedded_map))
> return 0;
>
> pad = L1_CACHE_BYTES - 1;
>
>
> Thanks

Thanks! This hash lookup is still a bit of a mystery to me.

I'll submit a 'fixup' patch momentarily, also removing:

--- linux.orig/arch/x86/mm/numa_64.c 2008-01-16 08:21:00.000000000 -0800
+++ linux/arch/x86/mm/numa_64.c 2008-01-16 09:57:27.168691249 -0800
@@ -35,8 +35,6 @@ u16 x86_cpu_to_node_map_init[NR_CPUS] __
[0 ... NR_CPUS-1] = NUMA_NO_NODE
};
void *x86_cpu_to_node_map_early_ptr;
-EXPORT_SYMBOL(x86_cpu_to_node_map_init);
-EXPORT_SYMBOL(x86_cpu_to_node_map_early_ptr);
DEFINE_PER_CPU(u16, x86_cpu_to_node_map) = NUMA_NO_NODE;
EXPORT_PER_CPU_SYMBOL(x86_cpu_to_node_map);

... to avoid section mismatches.

Thanks,
Mike