From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamal Hadi Salim Subject: Re: [PATCH v2 net] fq_codel: fix NET_XMIT_CN behavior Date: Mon, 6 Jun 2016 06:49:26 -0400 Message-ID: <57555536.1090801@mojatatu.com> References: <1465062227.2968.7.camel@edumazet-glaptop3.roam.corp.google.com> <20160604190301.GA8857@strlen.de> <1465070113.2968.18.camel@edumazet-glaptop3.roam.corp.google.com> <1465160087.2968.51.camel@edumazet-glaptop3.roam.corp.google.com> <1465160123.2968.52.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Florian Westphal , David Miller , netdev , Stas Nichiporovich To: Cong Wang , Eric Dumazet Return-path: Received: from mail-it0-f42.google.com ([209.85.214.42]:37896 "EHLO mail-it0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751125AbcFFKt2 (ORCPT ); Mon, 6 Jun 2016 06:49:28 -0400 Received: by mail-it0-f42.google.com with SMTP id i65so31976435ith.1 for ; Mon, 06 Jun 2016 03:49:28 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 16-06-05 07:30 PM, Cong Wang wrote: > Potentially all of the following: > > net/sched/sch_choke.c: return NET_XMIT_CN; > net/sched/sch_fifo.c: return NET_XMIT_CN; > net/sched/sch_generic.c: return NET_XMIT_CN; > net/sched/sch_gred.c: return NET_XMIT_CN; > net/sched/sch_hhf.c: return NET_XMIT_CN; > net/sched/sch_red.c: return NET_XMIT_CN; > net/sched/sch_sfb.c: return NET_XMIT_CN; > net/sched/sch_sfq.c: return NET_XMIT_CN; > As long as we are not loosing the stat that the packet is dropped. Some qdiscs have a counter which indicates congestion drops(look at RED variants of early drops); maybe codel needs one. The parent also must account for childs drops. BTW, returning NET_XMIT_CN could be confusing to tcp; it does not mean that the packet that we are getting return code for was dropped; it could mean _another_ packet in the queue was dropped. cheers, jamal