Messages in this thread | | | Date | Fri, 1 Nov 2002 11:17:04 -0700 | From | Matt Porter <> | Subject | Re: What's left over. |
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On Fri, Nov 01, 2002 at 10:50:45AM -0500, Gerald Britton wrote: > On Fri, Nov 01, 2002 at 03:25:01PM +0000, Linus Torvalds wrote: > > 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. > > This may be true of a typical workstation or large server, but your router > may not have such a modern CPU in it. Crypto accelerators are likely a > much bigger win on embedded routers or other small appliances with CPUs such > as the AMD Elan or other 486 to Pentium class processors.
Yes, and as a tangent, the same class of embedded devices also benefit from TCP/IP offload facilities. The same argument against a crypto-api supporting crypto hardware has been used in the past to argue against a Linux kernel TCP/IP hardware offload layer. The argument is completely invalid once one considers the typically lower speed of an embedded processor going into a crypto or network-edge device.
Even better, synthesizable SoC designs like IBM PPC4xx and reconfigurable processors architectures have opened further the concept of an on-chip crypto or tcp/ip offload macro cell which virtually eliminates PCI speed/latency concerns for these assist engines. It should be no surprise that embedded Linux is highly desired in these application specific processors.
Regards, -- Matt Porter porter@cox.net This is Linux Country. On a quiet night, you can hear Windows reboot. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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