Messages in this thread |  | | | Date | Sun, 12 Jun 2005 08:57:33 +0200 | | From | Ingo Molnar <> | | Subject | Re: [PATCH] local_irq_disable removal |
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* 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.
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