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SubjectRe: [PATCH 2/2] x86/mm/numa: remove the numa_nodemask_from_meminfo()
Hi,

Willing to hear from all of you :-)

On Mon, Feb 6, 2017 at 11:35 PM, Wei Yang <richard.weiyang@gmail.com> wrote:
> numa_nodemask_from_meminfo() is called to set bit according to
> numa_meminfo. While the only two places for this call is used to set proper
> bit to a copy of numa_nodes_parsed from numa_meminfo. With current code
> path, those numa node information in numa_meminfo is a subset of
> numa_nodes_parsed. So it is not necessary to set the bits again.
>
> The following is a code path analysis to prove the numa node information in
> numa_meminfo is a subset of numa_nodes_parsed.
>
> x86_numa_init()
> numa_init()
> Case 1
> acpi_numa_init()
> acpi_parse_memory_affinity()
> numa_add_memblk()
> node_set(numa_nodes_parsed)
> acpi_parse_slit()
> numa_nodemask_from_meminfo()
>
> Case 2
> amd_numa_init()
> numa_add_memblk()
> node_set(numa_nodes_parsed)
>
> Case 3
> dummy_numa_init()
> node_set(numa_nodes_parsed)
> numa_add_memblk()
>
> numa_register_memblks()
> numa_nodemask_from_meminfo()
>
> From the code path analysis, we can see each time a memblk is added, the
> proper bit is set in numa_nodes_parsed, which means it is not necessary to
> set it again in numa_nodemask_from_meminfo() for a copy of
> numa_nodes_parsed.
>
> This patch removes numa_nodemask_from_meminfo().
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> ---
> arch/x86/mm/numa.c | 21 +--------------------
> 1 file changed, 1 insertion(+), 20 deletions(-)
>
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 3e9110b34147..4c9070507a59 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -314,20 +314,6 @@ int __init numa_cleanup_meminfo(struct numa_meminfo *mi)
> return 0;
> }
>
> -/*
> - * Set nodes, which have memory in @mi, in *@nodemask.
> - */
> -static void __init numa_nodemask_from_meminfo(nodemask_t *nodemask,
> - const struct numa_meminfo *mi)
> -{
> - int i;
> -
> - for (i = 0; i < ARRAY_SIZE(mi->blk); i++)
> - if (mi->blk[i].start != mi->blk[i].end &&
> - mi->blk[i].nid != NUMA_NO_NODE)
> - node_set(mi->blk[i].nid, *nodemask);
> -}
> -
> /**
> * numa_reset_distance - Reset NUMA distance table
> *
> @@ -347,16 +333,12 @@ void __init numa_reset_distance(void)
>
> static int __init numa_alloc_distance(void)
> {
> - nodemask_t nodes_parsed;
> size_t size;
> int i, j, cnt = 0;
> u64 phys;
>
> /* size the new table and allocate it */
> - nodes_parsed = numa_nodes_parsed;
> - numa_nodemask_from_meminfo(&nodes_parsed, &numa_meminfo);
> -
> - for_each_node_mask(i, nodes_parsed)
> + for_each_node_mask(i, numa_nodes_parsed)
> cnt = i;
> cnt++;
> size = cnt * cnt * sizeof(numa_distance[0]);
> @@ -535,7 +517,6 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
>
> /* Account for nodes with cpus and no memory */
> node_possible_map = numa_nodes_parsed;
> - numa_nodemask_from_meminfo(&node_possible_map, mi);
> if (WARN_ON(nodes_empty(node_possible_map)))
> return -EINVAL;
>
> --
> 2.11.0
>

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