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    SubjectRe: [PATCH 0/8] v2 De-Couple sysfs memory directories from memory sections
      On 09/27/2010 09:09 PM, Nathan Fontenot wrote:
    > This set of patches decouples the concept that a single memory
    > section corresponds to a single directory in
    > /sys/devices/system/memory/. On systems
    > with large amounts of memory (1+ TB) there are perfomance issues
    > related to creating the large number of sysfs directories. For
    > a powerpc machine with 1 TB of memory we are creating 63,000+
    > directories. This is resulting in boot times of around 45-50
    > minutes for systems with 1 TB of memory and 8 hours for systems
    > with 2 TB of memory. With this patch set applied I am now seeing
    > boot times of 5 minutes or less.
    > The root of this issue is in sysfs directory creation. Every time
    > a directory is created a string compare is done against all sibling
    > directories to ensure we do not create duplicates. The list of
    > directory nodes in sysfs is kept as an unsorted list which results
    > in this being an exponentially longer operation as the number of
    > directories are created.
    > The solution solved by this patch set is to allow a single
    > directory in sysfs to span multiple memory sections. This is
    > controlled by an optional architecturally defined function
    > memory_block_size_bytes(). The default definition of this
    > routine returns a memory block size equal to the memory section
    > size. This maintains the current layout of sysfs memory
    > directories as it appears to userspace to remain the same as it
    > is today.

    Why not update sysfs directory creation to be fast, for example by using
    an rbtree instead of a linked list. This fixes an implementation
    problem in the kernel instead of working around it and creating a new ABI.

    New ABIs mean old tools won't work, and new tools need to understand
    both ABIs.

    error compiling committee.c: too many arguments to function

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      Last update: 2010-09-28 14:47    [W:0.021 / U:240.688 seconds]
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