Subject: Re: IFQ_MAXLEN: How large can it be?
To: Greg Troxel <>
From: Manuel Bouyer <>
List: tech-net
Date: 11/15/2006 22:56:18
On Wed, Nov 15, 2006 at 02:10:12PM -0500, Greg Troxel wrote:
>  So I bumped this number on our quite busy firewall up from 256 
>  to 1024 and later to 4096, but I still get 1'026'678 dropped 
>  packets during 8 days uptime.
> I think this is unwise and will just result in more memory stress.  If
> 4096 doesn't help, you're not keeping up often, or there's something
> else going on.  I'd be nervous putting this above 256 - people usually
> don't and then you'll be stressing the mbuf system more than others
> have stressed it and fixed it.

Well, actually you have to bump it if you have more than one busy interface
with large ring. The wm interface can have a ring of 256 packet, so
you could get in worse case 256 packets in one interrrupt; and if you have
more than one interface you loose.

BTW, Christoph, where do you see these drops ? On the IP input queue, or
interfaces output queues ?

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference