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    SubjectRe: vmalloced stacks on x86_64?
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    On Fri, 2014-10-24 at 19:38 -0700, H. Peter Anvin wrote:
    > On 10/24/2014 05:22 PM, Andy Lutomirski wrote:
    > > Is there any good reason not to use vmalloc for x86_64 stacks?
    >
    > Additional TLB pressure if anything else.

    It seems TLB pressure gets less and less interest these days...

    Is it still worth trying to reduce it ?

    I was wondering for example why 'hashdist' is not cleared if current
    host runs a NUMA enabled kernel, but has a single node.

    Something like following maybe ?

    diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
    index 7dbe5ec9d9cd08afac13797e2adac291fb703eec..0846ef054b0620a7be0c6f69b1a2f21c78d57d3b 100644
    --- a/Documentation/kernel-parameters.txt
    +++ b/Documentation/kernel-parameters.txt
    @@ -1181,7 +1181,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
    hashdist= [KNL,NUMA] Large hashes allocated during boot
    are distributed across NUMA nodes. Defaults on
    for 64-bit NUMA, off otherwise.
    - Format: 0 | 1 (for off | on)
    + Format: 0 | 1 | 2 (for off | on if NUMA host | on)

    hcl= [IA-64] SGI's Hardware Graph compatibility layer

    diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
    index 1a883705a12a8a12410914be93b2ee65807cc423..8aded4c11c8c1cc5778e9ae2b9cd5146070b5b03 100644
    --- a/arch/x86/mm/numa.c
    +++ b/arch/x86/mm/numa.c
    @@ -668,7 +668,8 @@ static int __init dummy_numa_init(void)

    node_set(0, numa_nodes_parsed);
    numa_add_memblk(0, 0, PFN_PHYS(max_pfn));
    -
    + if (hashdist == HASHDIST_DEFAULT)
    + hashdist = 0;
    return 0;
    }




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