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Question about Linus' QOTWQuestion about Linus' QOTWPosted Aug 25, 2011 15:40 UTC (Thu) by bronson (subscriber, #4806)In reply to: Question about Linus' QOTW by pr1268 Parent article: Quotes of the week
Right. Instead of just switching to a 1-cycle bit shift, the author wrote a 64 bit do_div for 32 bit architectures that presumably takes ungodly cycles. Which, if I'm understanding correctly, is fairly insane.
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Question about Linus' QOTW Posted Aug 25, 2011 16:30 UTC (Thu) by hmh (subscriber, #3838) [Link] Linus says this later (which I also consider QotW material): Big 64-bit divides are bad bad bad. They are so horrendously bad on 32-bit that we don't even support them. Which is in no way an overstatement of the badness, so I think you got it just right. It is ungodly expensive, indeed.
Question about Linus' QOTW Posted Aug 25, 2011 17:51 UTC (Thu) by blitzkrieg3 (subscriber, #57873) [Link] do_div was already there
http://lxr.linux.no/#linux+v3.0.3/arch/x86/include/asm/div64.h#L20
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