Hi,
On Mon, Mar 04, 2013 at 11:58:23AM -0600, Jon Hunter wrote:
> >>> while (isr) {
> >>> unsigned long bit = __ffs(isr);
> >>>
> >>> /* clear this bit */
> >>> isr &= ~bit;
> >>>
> >>> generic_handle_irq(irq_find_mapping(bank->domain, bit);
> >>> }
> >>>
> >>> this way you will only iterate the amount of bits enabled in the isr
> >>> register.
> >>
> >> Definitely cleaner but I am wondering which approach would be more
> >> efficient from an instruction standpoint. This could definitely be much
> >> more efficient if there is only a couple bits set.
> >
> > __ffs() is done with CLZ instruction, so it's pretty fast.
>
> Ok, yes I see that now for ARMv5 onwards. Grant has pushed the patch,
> but may be we can update this as an optimisation separately.
sure, that was my suggestion from the beginning :-) It's clearly subject
to a separate patch.
--
balbi
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