From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH 1/1] net_sched: drr: warn when qdisc is not work conserving Date: Thu, 12 Jun 2014 18:38:03 +0200 Message-ID: <20140612163803.GD1982@breakpoint.cc> References: <1402511718-24203-1-git-send-email-fw@strlen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Florian Westphal , netdev@vger.kernel.org To: Patrick McHardy Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:55486 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753068AbaFLQiF (ORCPT ); Thu, 12 Jun 2014 12:38:05 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Patrick McHardy wrote: > On 11. Juni 2014 20:35:18 MESZ, Florian Westphal wrote: > >The DRR scheduler requires that items on the active list are work > >conserving, i.e. do not hold on to skbs for throttling purposes, etc. > >Attaching e.g. tbf renders DRR useless because all other classes on the > >active list are delayed as well. > > > >So, warn users that this configuration won't work as expected; we > >already do this in couple of other qdiscs, see e.g. > > Why don't prevent this during configuration time in the first place? > It doesn't work, a warning might trigger long after creating the broken > configuration and will more likely go unnoticed. That would be nice. But that would require some annotation of the qdiscs wheter they're wc or not, right? With such annotation, qdisc_graft() could refuse such request. Is that what you have in mind?