Subject: Re: Queue length
To: =?iso-8859-1?Q?P=E5l_Halvorsen?= <>
From: Manuel Bouyer <>
List: tech-kern
Date: 06/27/2001 21:24:51
On Wed, Jun 27, 2001 at 09:18:35AM +0200, Pål Halvorsen wrote:
> Hi!
> I'm sending data (with UDP/IP in an in-kernel data-path) too fast for the
> NIC, and the queue is filled up making the system to dropp packets with
> error ENOBUFS. Both ip_output and if_etheroutput checks the
> ifp->if_snd.ifq_maxlen which is by default
> IFQ_MAXLEN (50)!!?? Is this value increased somewhere if the queue starts
> to fill, because I printed this value and is says 511.....

Some interface drivers set it to something different than IFQ_MAXLEN.

> Could it help to increase this value?

It depends on your use, but it you're sending data faster than what the NIC
can cope, without mechanism to adjust the rate, then you're always going
to fill up the queue, whatever its size is.

Manuel Bouyer <>