From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [net-next PATCH 1/1 V4] qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE Date: Mon, 29 Sep 2014 22:14:31 +0200 Message-ID: <20140929221431.3e322aab@redhat.com> References: <20140924160932.9721.56450.stgit@localhost> <20140924161047.9721.43080.stgit@localhost> <1411579395.15395.41.camel@edumazet-glaptop2.roam.corp.google.com> <20140924195831.6fb91051@redhat.com> <54234225.5000503@mojatatu.com> <20140925102505.494acab1@redhat.com> <54240F34.1050707@mojatatu.com> <20140925165738.646d0783@redhat.com> <20140925172329.7460f787@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Tom Herbert , Jamal Hadi Salim , Eric Dumazet , Linux Netdev List , "David S. Miller" , Alexander Duyck , Toke =?UTF-8?B?SMO4aWxh?= =?UTF-8?B?bmQtSsO4cmdlbnNlbg==?= , Florian Westphal , Dave Taht , John Fastabend , Daniel Borkmann , Hannes Frederic Sowa To: Jesper Dangaard Brouer Return-path: Received: from mx1.redhat.com ([209.132.183.28]:61173 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754027AbaI2UPJ (ORCPT ); Mon, 29 Sep 2014 16:15:09 -0400 In-Reply-To: <20140925172329.7460f787@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 25 Sep 2014 17:23:29 +0200 Jesper Dangaard Brouer wrote: > I will redo the tests, once I get home to my testlab, as the remote lab > I'm using now is annoyingly slow rebooting machines, as we not longer > have a runtime option for enable/disable (I'm currently in Switzerland). I'm going to change the bulking "budget" from 8 packet to 7 packets, based on my netperf-wrapper test. I've designed some tests for the tool "netperf-wrapper" that tries to measure the HoL blocking effect. I've turned down the link speed to 100Mbit/s on driver igb. And uses a single TXQ setup (cmdline: ethtool -L eth1 combined 1). I can now show some kind of HoL blocking effect. The strange part is the HoL effect only occurs above 8 packets, 7 packet and below show no bad effect of this bulking patch. Results 100Mbit/s test qdisc_prio_hol, latency in high prio band: * GSO: stable average on 2.23ms * TSO: varies between min 4.13ms to 4.41ms (range 0.28ms) * No bulking: stable average on 1.71ms (3x outliners on 1.95ms) * Bulking(8): varies between 1.71ms to 1.95ms (range 0.24ms) * Bulking(7): stable average on 1.71ms (1x outliner on 1.95ms) * Bulking(6): stable average on 1.71ms (3x outliners on 1.91ms) * Bulking(5): stable average on 1.71ms (1x outliner on 1.91ms) * Bulking(5): stable average on 1.71ms (1x outliner on 1.91ms) * Bulking(4): stable average on 1.71ms (0x outliner) Bulking(8) the calculation: * Added delay were 0.24ms (1.95 - 1.71ms) corrosponding to 3000 bytes * 1500 bytes *8 / 100Mbit = 0.12 ms * (100*10^6)*(1.95/10^3)/8 = 24375 bytes * (100*10^6)*(1.71/10^3)/8 = 21375 bytes * Added HoL: 3000 bytes * Still compared to TSO and GSO, the added HoL blocking is small. -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer