Date: Mon, 16 Oct 2006 14:01:07 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-hardware@FreeBSD.ORG, soralx@cydem.org Subject: Re: Quiet computer Message-ID: <200610161201.k9GC17ol003191@lurza.secnetix.de> In-Reply-To: <200610150041.59870.soralx@cydem.org>
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soralx@cydem.org wrote:
>
> neither do I care how fast it is on someone else's system :p, but I'm
> just curious whether the speed VIA claims, 25Gbps(!) peak is achievable
Note that that number is just the "raw" rate at which the
circuit can produce bits. You still have some processing
overhead in the kernel and in the userland application
that uses the random device. There's no "zero-copy random
device" yet. ;-)
I also think that 25 Gbit/s is overly optimistic. I guess
it can only achieved for a short period ("burst"), hence
they call it peak. It's certainly not designed to keep
that data rate for a longer sustained period.
> > I just care that it offloads the ALU. I haven't gotten around to
> > proving whether (and by how much) it does so.
>
> did you get to the point that you're sure it's being used?
Now that's easy. Just type "sysctl kern.random". If you
get a bunch of lines talking about "yarrow" and "harvest",
then the kernel's software PRNG is used. If you get an
error message "unknown oid 'kern.random'", then a hardware
generator is being used.
Best regards
Oliver ("VIA C3 Nehemiah+RNG+AES ")
--
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.
"Unix gives you just enough rope to hang yourself --
and then a couple of more feet, just to be sure."
-- Eric Allman
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