Re: AES assembler optimizations

[H. Peter Anvin]

Followup to:  <20040809171231.GG2716@xxxxxxxxxxxxxxxxxxx>
By author:    Matti Aarnio <matti.aarnio@xxxxxxxxxxx>
In newsgroup: linux.dev.kernel
> 
> Usage of MMX inside the Linux kernel is like the usage of FP inside
> the Linux kernel:  Can be done after jumping complex hoops, BUT NOT
> RECOMMENDED... (MMX in intertwined with FP hardware, after all.)
> 
> You have to do lots of the MMXes in order to win after amortizing those
> necessary hoops...  RAID-5 code does XOR via MMX code, under some 
> conditions.  ... where that happens to become a win.
> 

It's not really that hard, you just have to have enough work to
amortize it over.  The two metrics are: how much work do you get per
call, and how much work do you get before the next schedule().

	-hpa
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