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    SubjectRe: [PATCH] local_irq_disable removal

    * Thomas Gleixner <tglx@linutronix.de> wrote:

    > On Sat, 2005-06-11 at 13:51 -0700, Daniel Walker wrote:
    > > On Sat, 11 Jun 2005, Ingo Molnar wrote:
    >
    > > Interesting .. So "cli" takes 7 cycles , "sti" takes 7 cycles. The current
    > > method does "lea" which takes 1 cycle, and "or" which takes 1 cycle. I'm
    > > not sure if there is any function call overhead .. So the soft replacment
    > > of cli/sti is 70% faster on a per instruction level .. So it's at least
    > > not any slower .. Does everyone agree on that?
    >
    > No, because x86 is not the whole universe

    x86 is actually a 'worst-case', because it has one of the cheapest CPU
    level cli/sti implementations. Usually it's the hard-local_irq_disable()
    overhead on non-x86 platforms that is a problem. (ARM iirc) So in this
    sense the soft-flag should be a win on most sane architectures.

    Ingo
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