Subject: Re: FreeBSD Bus DMA
To: David Edelsohn <>
From: Simon Burge <>
List: tech-kern
Date: 06/13/1998 11:29:22
On Fri, 12 Jun 1998 15:09:00 -0400  David Edelsohn wrote:

> >>>>> "John S Dyson" writes:
> John> I compile exactly the same code, for the same target NetBSD
> John> platform, the only difference is running freebsd emulation of
> John> NetBSD for compiling the platform.  The compile times compiling
> John> EXACTLY the same code, in EXACTLY the same circumstance, on 
> John> EXACTLY the same hardware, for EXACTLY the same NetBSD client.
> John> We are either cross-compiling the target code under NetBSD, or
> John> cross compiling the target code under FreeBSD.  Absolutely
> John> no differences in the code being compiled.
> >> 1) the code base being compiled
> John> Our product.
> >> 2) the compile times
> John> About 1.5Hrs vs. about 30-40mins or so.
> >> 3) the machine types
> John> X86. 
> >> 4) the versions of the OS that were running.
> John> FreeBSD-current, vs. a recent NetBSD.
> Separately you also have mentioned 256MB physical memory and that your
> entire product including header files, the working set of the toolchain,
> and the OS all fit within your physical memory.

So, conceivably, you may be able to get something similar with NetBSD
by setting the BUFPAGES option (ie, the size of the byuffer cache) to a
size that equates to say 200MB on a 256MB RAM machine?  Obviously this
is no where near as useful in day-to-day life as a merged VM/buffer
cache setup, but probably less effort than most vendors go to to get
good SPEC numbers...