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    SubjectRe: [PATCH RT 00/02] SLOB optimizations

    * Eric Dumazet <dada1@cosmosbay.com> wrote:

    > >while it could possibly be cleaned up a bit, it's one of the
    > >best-optimized subsystems Linux has. Most of the "unnecessary
    > >complexity" in SLAB is related to a performance or a debugging feature.
    > >Many times i have looked at the SLAB code in a disassembler, right next
    > >to profile output from some hot workload, and have concluded: 'I couldnt
    > >do this any better even with hand-coded assembly'.
    >
    > Well, I miss a version of kmem_cache_alloc()/kmem_cache_free() that
    > wont play with IRQ masking.

    sure, but adding this sure wont reduce complexity ;)

    > The local_irq_save()/local_irq_restore() pair is quite expensive and
    > could be avoided for several caches that are exclusively used in
    > process context.

    in any case, on sane platforms (i386, x86_64) an irq-disable is
    well-optimized in hardware, and is just as fast as a preempt_disable().

    Combined with the fact that CLI/STI has no register side-effects, it can
    even be faster/cheaper, on x86 at least.

    Ingo
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