RE: [PATCH] x86/apic: Use div64_ul() instead of do_div()

[H. Peter Anvin]

>> 
>> Change deltapm to unsigned long and replace do_div() with div64_ul()
>> which doesn't implicitly cast the divisor and doesn't unnecessarily
>> calculate the remainder.
>
>Eh? they are entirely different beasts.
>
>do_div() does a 64 by 32 divide that gives a 32bit quotient.
>div64_ul() does a much more expensive 64 by 64 divide that
>can generate a 64bit quotient.
>
>The remainder is pretty much free in both cases.
>If a cpu has a divide instruction it will almost certainly
>put the result in one register and the quotient in another.
>

Not on e.g. RISC-V.