Slack 7.0 running a vanilla 2.2.18 kernel lo mtu is 3924.
Slack 8.0 running 2.4.17 lo mtu is 16436.

Fran
:):):)

On Fri, 04 Jan 2002 17:40, you wrote:
> On Fri, 4 Jan 2002, Juha Saarinen wrote:
> > > Did you fiddle yours ? As you can see, my lo adapter has a much
> > > smaller MTU.. from a default slackware 7.1 install. I also note that
> > > your one has a lot more activity than mine :)
> >
> > Nope... ~16KB seems to be the default. Checked two other RHL boxes,
> > plus two FreeBSD 4.x systems which have the same. BSDi 4.1 uses 4,352
> > bytes though.
>
> If you go into /usr/src/linux/drivers/loopback.c you'll see
> that the MTU of your loopback device is hard-coded. YMMV!
> on my SuSE 7.1 box running 2.2.18, it's 3924 but on 7.3 with
> a lovingly hand-crafted 2.4.16 (with PPPoATM bits added),
> it's 16KB or --
>
> dev->mtu = (16 * 1024) + 20 + 20 + 12;
>
> They've been gradually increasing the size with successive
> kernel versions. It's tuned so that when the kernel allocates
> space for the loopback pseudodevice's data in memory, so it
> all *just* fits into one page. Too large, you thrash your disk.
> routing. Too small, you're making too many calls to kmalloc.
>
> Read The Source, Luke!
>
> Cheryl

-- 
This message is part of the NZ ADSL mailing list. 
see http://unixathome.org/adsl/ for archives, FAQ, 
and various documents. 
To unsubscribe: send mail to majordomo@lists.unixathome.org 
with "unsubscribe adsl" in the body of the message