Re: [PATCH 2/4] lib: vsprintf: Optimize division by 10000

[Michal Nazarewicz]

On Mon, Sep 24 2012, George Spelvin wrote:
>> You are using a 64-bit multiply in a path that is designed for 32-bit
>> processors, which makes me feel that it will be slower.
>
> Slower than the divide it's replacing?

OK, granted, it might be faster after all. ;)  Still, I'd love to see
some benchmark.

> The following 32-bit processors have 32x32->64-bit multiply:
>
> x86
> ARM (as of ARMv4 = ARM7TDMI, the lowest version in common use)
> SPARCv7, SPARCv8

Didn't some SPARCs have 32x32->32 multiply?  I remember reading some
rant from a GMP developer about how SPARC is broken that way.

> MIPS32
> MC68020
> PA-RISC 1.1 (XMPYU)
> avr32
> PowerPC (MULHWU)
> VAX (EMUL)

> I could do some Kconfig hacking and make the code path
> architecture-dependent.  Do you think it's worth it?

Definitely not.

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