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Re: GSoc2010 project suggestion: swcryptX
I mostly have no comment on this. But I did notice something:
> Offloading the cryptographic requests involves some overhead.
> Data needs to be transferred to the hardware and back. On
> systems with a slow CPU, this overhead is relatively small
> compared to the operation speed of the CPU. On faster CPUs, the
> overhead becomes more of a burden, making the benefit of the
> crypto hardware negligible.
This isn't just a question of CPU speed; also relevant are
- Does the CPU have anythiing else useful to do? If so, using crypto
hardware may be worth it even if it's slower than the main CPU at
the relevant operation (in which case it's not worth it if the CPU
has nothing better to do).
- How does the expense of just moving the data (including, eg, cache
effects), independent of the cost of the operation itself, compare
to the cost of doing the operation on the main CPU? Sometimes even
fast hardware is rendered effectively useless by setup cost.
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