From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: inaccurate packet scheduling Date: Wed, 02 Jan 2013 08:34:42 -0800 Message-ID: <1357144482.21409.16876.camel@edumazet-glaptop> References: <1355849503.9380.37.camel@edumazet-glaptop> <20130102152601.GB1532@minipsycho.orion> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: edumazet@google.com, netdev@vger.kernel.org To: Jiri Pirko Return-path: Received: from mail-da0-f50.google.com ([209.85.210.50]:59598 "EHLO mail-da0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752964Ab3ABQeq (ORCPT ); Wed, 2 Jan 2013 11:34:46 -0500 Received: by mail-da0-f50.google.com with SMTP id h15so6553641dan.9 for ; Wed, 02 Jan 2013 08:34:45 -0800 (PST) In-Reply-To: <20130102152601.GB1532@minipsycho.orion> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2013-01-02 at 16:26 +0100, Jiri Pirko wrote: > Tue, Dec 18, 2012 at 05:51:43PM CET, erdnetdev@gmail.com wrote: > >On Tue, 2012-12-18 at 08:26 -0800, Stephen Hemminger wrote: > > > >> Check kernel log for messages about clock. It could be that on the > >> machines with issues TSC is not usable for kernel clock. > >> Also turn off TSO since it screws up any form of rate control. > > > >Yes, but we should fix it eventually. I'll take a look. > > Hi Eric, did you have a chance to look at this? Or should I give it a try? I took a look, and TBF does : if (qdisc_pkt_len(skb) > q->max_size) return qdisc_reshape_fail(skb, sch); We have several choices : 1) Add a one time warning 2) cap dev->gso_max_size at Qdisc setup time 3) Re-segment the packet instead of dropping it (if GSO packet), and call the expensive qdisc_tree_decrease_qlen() function. 4) remove max_size limitation