FreeBSD 5.3 Bridge performance take II

Robert Watson rwatson at
Thu Sep 9 20:02:06 PDT 2004

On Thu, 9 Sep 2004, jason wrote:

> >>If you're not already disabling harvesting of entropy on interrupts and
> >>in network processing, you really want to for performance purposes.
> >>    
> >
> >How do I disable this without causing entropy starvation for "typical" use
> >cases (ssl? ssh?)? I googled a bit and found nothing at all about how to
> >disable excessive harvesting.
> >
> ># sysctl -a | grep harvest
> >kern.random.sys.harvest.ethernet: 1
> >kern.random.sys.harvest.point_to_point: 1
> >kern.random.sys.harvest.interrupt: 1
> >kern.random.sys.harvest.swi: 0
> >
> >These are the knobs I know about. Is it enough to turn
> >kern.random.sys.harvest.ethernet and kern.random.sys.harvest.interrupt to 0,
> >or are there other things I need to do too?

I'd set kern.random.sys.harvest.ethernet to 0 because the incremental
benefits beyond harvesting the interrupt are pretty low.

> That is what I did.  I have not bench marked, but I did allot of
> searching on the web and reading man pages.  I just can't make the
> changes permanent.  When I put them in loader.conf they seem to be
> ignored.  Any suggestions to make it stick? 

I've CC'd markm because he's probably interested -- right now, you have to
set it in /etc/sysctl.conf because a tunable is not defined.  I think it
would be a good idea to make them tunable, however, as well.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at      Principal Research Scientist, McAfee Research

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