Subject: Re: [net-next PATCH 1/3] net: make default tx_queue_len configurable

From: Phil Sutter <[email-masked]>
Date: Wed, 29 Jul 2015 23:34:28 +0200

On Wed, Jul 29, 2015 at 11:06:18PM +0200, Florian Westphal wrote:
> Phil Sutter <[email-masked]> wrote:
[...]
> > +config DEFAULT_TX_QUEUE_LEN
> > +	prompt "Default TX queue length (in packets)" if EXPERT
> > +	int
> > +	default 1000	# Ethernet wants good queues
> > +	help
> > +	  Set the default value of tx_queue_len for newly created network
> > +	  interfaces. It is used by queueing disciplines to determine how many
> > +	  packets to keep in backlog before starting to drop new ones.
> > +
> > +	  The default value of 1000 packets is there for a very long time and
> > +	  in combination with GSO way too big.
> > +
> 
> I can't see how this could be used in a meaningful way.
> 
> No distro is going to touch this.
> 
> I don't think sysctl value would help either.

I just didn't want to introduce yet another magic value assignment. It's
merely a #define with a little flexibility and a subtle note that the
default should be changed attached.

Cheers, Phil