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    SubjectRe: [PATCH 22/23] sysctl arm: Remove binary sysctl support
    > Can you name one binary sysctl value that gets accessed more
    > than a few times during the execution of a vaguely common
    > application? We're talking about microseconds for typically
    > write-once or read-once settings.

    For example shell scripts tend to execute programs quite a lot.

    > The question is just how many sysctl values you regard as both
    > common and performance critical.

    Very little, I suspect in fact it's only one.

    > > > in glibc-ports for the support of arm inb/outb. The only other
    > > > use in older glibc was checking to see if we ran on an SMP kernel.
    > >
    > > That older glibc is widely deployed. And it won't go away next year.
    > So? Most users of old glibc are also using old kernels, and they

    How do you know? At least here it's quite common to use new kernels
    with old user land.

    > can still use the config option for the compatibility code.
    > There wouldn't even be a performance penalty over new glibc with
    > new kernels which already use procfs.

    When he drops the sysctl(2) API completely the old userland will
    be unhappy.

    > > I just think you should have two flavours of emulation layer:
    > > full and "common sysctls". This can be probably done with the same
    > > code and some strategic ifdefs.
    > If it's just about code size, I totally wouldn't bother. Just put the
    > emulation code in loadable module and add a 'printk("Warning, %s is
    > using sysctl %s, wasting %d kb of kernel memory")' to it's module_init
    > function.

    That means non modular kernels can't support old userland.

    -- -- Speaking for myself only.

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