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    SubjectRe: [PATCH 1/3] netfilter : 3 patches to boost ip_tables performance
    On Wed, Sep 21, 2005 at 11:29:13PM +0200, Eric Dumazet wrote:
    > Patch 1/3
    >
    > 1) No more one rwlock_t protecting the 'curtain'

    I have no problem with this change "per se", but with the
    implementation.

    As of now, we live without any ugly #ifdef CONFIG_SMP / #endif sections
    in the code - and if possible, I would continue this good tradition.

    For example the get_counters() function. Wouldn't all the smp specific
    code (for_each_cpu(), ...) be #defined to nothing anyway?

    And if we really need the #ifdef's, I would appreciate if those
    sectionas are as small as possible. in get_counters() the section can
    definitely be smaller, rather than basically having the whole function
    body separate for smp and non-smp cases.

    Also, how much would we loose in runtime performance if we were using a
    "rwlock_t *" even in the UP case?. I mean, it's just one more pointer
    dereference of something that is expected to be in cache anyway, isn't
    it? This gets rid of another huge set of #ifdefs that make the code
    unreadable and prone to errors being introduced later on.

    --
    - Harald Welte <laforge@netfilter.org> http://netfilter.org/
    ============================================================================
    "Fragmentation is like classful addressing -- an interesting early
    architectural error that shows how much experimentation was going
    on while IP was being designed." -- Paul Vixie
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