Messages in this thread | | | Date | Sat, 11 Jun 2005 13:51:47 -0700 (PDT) | From | Daniel Walker <> | Subject | Re: [PATCH] local_irq_disable removal |
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On Sat, 11 Jun 2005, Ingo Molnar wrote:
> > * Esben Nielsen <simlo@phys.au.dk> wrote: > > > > the jury is still out on the accuracy of those numbers. The test had > > > RT_DEADLOCK_DETECT (and other -RT debugging features) turned on, which > > > mostly work with interrupts disabled. The other question is how were > > > interrupt response times measured. > > > > > You would accept a patch where I made this stuff optional? > > I'm not sure why. The soft-flag based local_irq_disable() should in fact > be a tiny bit faster than the cli based approach, on a fair number of > CPUs. But it should definitely not be slower in any measurable way.
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?
Daniel
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