Messages in this thread | | | Date | Sat, 02 Nov 2002 00:15:04 +0800 | From | Michael Clark <> | Subject | Re: What's left over. |
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On 11/01/02 23:25, Linus Torvalds wrote: > In article <20021031194351.GA24676@tapu.f00f.org>, > Chris Wedgwood <cw@f00f.org> wrote: > >>On Thu, Oct 31, 2002 at 10:49:10AM -0800, Linus Torvalds wrote: >> >> >>>Any hardware that needs to go off and think about how to encrypt >>>something sounds like it's so slow as to be unusable. I suspect that >>>anything that is over the PCI bus is already so slow (even if it >>>adds no extra cycles of its own) that you're better off using the >>>CPU for the encryption rather than some external hardware. >> >>Except almost all hardware out there that does this stuff is async to >>some extent... > > > That's not my argument. I realize that external hardware on a PCI bus > _has_ to be asynchronous, simply because it is so slow. > > The question I have is whether such external hardware is even worth it > any more for any standard crypto work. With a regular PCI bus > fundamentally limiting throughput to something like a maximum of 66MB/s > (copy-in and copy-out, and that's so theoretical that it's not even > funny - I'd be surprised if RL throughput copying back and forth over a > PCI bus is more than 25-30MB/s), I suspect that you can do most crypto > faster on the CPU directly these days. > > Maybe not. The only numbers I have is the slowness of PCI.
A 1GHz PIII will do about 8MBytes/sec of 3DES
Plug in a 2.4Gbs broadcom crypto chip into a 64bit PCI-X slot with the same CPU and you should be capable of doing at least 10 times that.
Stuff like RSA is much slower (and benefits more from hardware)
BTW - there are some outdated cryptolib patches with an async interface around somewhere (along with patches for freeswan to use the async api).
I guess the crypto guys like Chris will add the async API if they need it (which they do i think ;).
~mc
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