Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 15 Jul 2003 14:52:50 -0700 | From | george anzinger <> | Subject | Re: do_div64 generic |
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Bernardo Innocenti wrote: > On Tuesday 15 July 2003 07:38, Andrew Morton wrote: > > >>> Here's a patch that takes care of all architectures. >> >>AFAICT, we can just rework posix-timers.c to use the standard do_div() and >>be done with it, can we not? ie: no div_long_long_rem(), no >>div_ll_X_l_rem(). Just do_div(). > > > We could, and it would be easy and almost as efficient in all places > where div_long_long_rem() is being used: > > value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec); > > becomes: > > value->tv_nsec = do_div(nsec, NSEC_PER_SEC); > value->tv_sec = nsec; > > George, do you agree? May I go on and post a patch killing > div_long_long_rem() everywhere?
The issue is that div is a very long instruction and the do_div() thing uses 2 or three of them, while the div_long_long_rem() is just 1. Also, a lot of archs already have the required div by a different name. It all boils down to a performance thing.
-g > > >>Please use `static inline', not `extern inline', btw. > > > Oops. Fixed. I had just copied it over from asm-i386/div64.h. > > Is it worth posting a big patch to replace all remaining > occurrences of 'extern inline' all over the kernel? > > I'd also like to point out that __inline__ is often being > used inconsistently. We should be using __inline__ rather > than inline in public headers needed by glibc for apps > compiled with -ansi. Since it's so ugly, it shouldn't > be used in other places. >
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
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