Messages in this thread | | | Date | Thu, 1 Mar 2007 02:29:19 +0100 (CET) | From | Tim Schmielau <> | Subject | Re: [PATCH] udivdi3: 64 bit divide |
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On Tue, 27 Feb 2007, Andrew Morton wrote: > > On Mon, 26 Feb 2007 17:35:17 -0800 Stephen Hemminger <shemminger@linux-foundation.org> wrote: > > The kernel already has several implmentations and usages of 64 by 64 > > bit divide. > > > > Although it is significantly slower, there are places that need it so > > provide one generic version using scaling, and allow existing platform > > versions to continue. > > The reason we implement 64/32 via do_div() is, for better or for worse, to > make people think before they use it. And to make it stand out, and so > that we discover places that are using it by accident, where they could use > something cheaper.
IMHO it is even more important that the user of your 64/64 div is aware that it only returns an approximate result.
I certainly don't want to have any code in the kernel that by accident makes an allocation a few bytes short of the actual size of the object (just to make up a drastic example).
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