Messages in this thread | | | Date | Sun, 12 Jun 2005 21:02:41 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] local_irq_disable removal |
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* Zwane Mwaikambo <zwane@fsmlabs.com> 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? > > Well you also have to take into account the memory access, so it's not > always that straightforward.
preempt_count resides in the first cacheline of 'current thread info' and is almost always cached. It's the same cacheline that 'current', 'smp_processor_id()' are using.
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