Subject: Re: FreeBSD Bus DMA
To: Matthew Jacob <>
From: John S. Dyson <>
List: tech-kern
Date: 06/12/1998 16:10:38
Matthew Jacob said:
> John S. Dyson wrote:
> >
> > To me, a machine with 256MB is very desirable, because FreeBSD
> > makes very effective use of the memory.  I really forget
> > what the effect of memory is on NetBSD (both MACH and UVM),
> > but I suspect that it doesn't help very much (only to cache
> > programs.)
> > 
> Really? Well, NASA/AMES has several machines with > 256MB memory
> (including
> a couple 8200's with 2GB)- seems to make some things a lot better,
> but to be honest I haven't actually done real benchmarks on them to
> see what the actual effects are. Mostly what we're trying to see is
> the effects of 64k and larger blocksizes. Seems to help to have the
> larger memory- but that's just a 'feel' for it.
Yes, I suppose that if you tune-up the buffer cache it could help.
I was kind-of thinking about default configs, but one should only
tune the buffer cache so far, deu to tradeoff issues.

John                  | Never try to teach a pig to sing,     | it just makes you look stupid,         | and it irritates the pig.