Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 15 Jul 2003 17:07:35 -0700 | From | george anzinger <> | Subject | Re: do_div64 generic |
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Andrew Morton wrote: > george anzinger <george@mvista.com> wrote: > >>>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. > > > It is only used in nanosleep(), and then only in the case where the sleep > terminated early. > > If someone is calling nanosleep() so frequently for this to matter, the > time spent in divide is the least of their problems. Unless you have some > real-worldish benchmarks to demonstrate otherwise?
It is also used in the jiffies to timespec and jiffies to timeval code in timer.h, if memory serves. > > You know what they say about premtur optmstns, and having to propagate > funky new divide primitives across N architectures is indeed evil.
Hm. I only want the simple div. 64-bit/32-bit in two 32-bit results. Is this funky? And the "evil" #ifdef allows archs to not do it. > > Bernardo, can you do the patch please? > >
-- 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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