FreeBSD beginner (NetBSD advanced)

Matthew Seaman m.seaman at
Thu Jul 15 12:30:19 PDT 2004

On Thu, Jul 15, 2004 at 08:30:10PM +0200, Wojciech Puchar wrote:
> i want to go to FreeBSD instead of NetBSD on my i386 machines because of 
> all "new features" :( introduced in NetBSD after 1.5 mostly crashing
> softdeps, strange memory/unified disk cache management (large writing to 
> file almost freezes everything) etc. etc.
> i installed FreeBSD once to do quick performance tests, and at least in 
> disk I/O and fair scheduling it's MUCH better (tested 4.10 and 5.1).
> my questions:
> 1) what is Buf and Cache in top exactly? why buf on 96MB machine gets to 
> near 20MB and never goes down? it's almost 1/4 of memory size.

These are part of the kernel VM system -- most of that space is used
for buffering IO to disk drives or other devices.  There are various
VM related sysctls you can use to tune things, but unless you've got a
pretty exceptional system just going with the defaults will probably
give you the best results.

> 2) can i compile kernel with -march=pentium,pentium[234] -O2 optimization?
> in NetBSD 2.0 doing -march=pentium produces kernel that doesn't boot at 
> all, just resets.

You can certainly compile with a different CPUTYPE setting in
/etc/make.conf -- works very well.

However under 4.x and any of the releases from 5.x to date you
shouldn't use any more that -O optimization.  There's a push on to
make world+kernel compile correctly using -O2 before 5.3-STABLE, but
that's not been completed yet.
> 3) how can i disable compiling, using etc.. all that LKM (KLD) stuff?
> i really prefer one static kernel.

Generally what happens is that a driver is either built into a kernel
image, or it's built as a loadable module.  Writing your own kernel
configuration to include the drivers for all of your hardware isn't
too difficult.  You can prevent any LKMs being build by setting:


in /etc/make.conf
> 4) is IPv6 working well? (i mean no crashes etc...) i will get real IPv6 
> zone allocation soon and want to use it.

Works for me.  But FreeBSD uses the same Kame IPv6 stack as NetBSD -- 
> 5) what is used in FreeBSD for traffic management. NetBSD has altq - 
> please just give me a name i will RTFM.

> 6) how to turn using serial port as console on i386? my home machine is 
> headless, i'm using X terminals to access it.

Simple.  It's pretty easy to install the system that way too:

> 7) does FreeBSD support 2 CPUs on i386?

Yes.  You will have to compile a custom kernel to get SMP support
under 4.x (you can always boot a UP kernel on a MP machine).  For 5.x,
it should all just work with the GENERIC kernel.



Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP:         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url :

More information about the freebsd-questions mailing list