{"id":807774,"url":"http://patchwork.ozlabs.org/api/1.0/covers/807774/?format=json","project":{"id":7,"url":"http://patchwork.ozlabs.org/api/1.0/projects/7/?format=json","name":"Linux network development","link_name":"netdev","list_id":"netdev.vger.kernel.org","list_email":"netdev@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20170830172458.18544-1-fw@strlen.de>","date":"2017-08-30T17:24:56","name":"[net-next,0/2] tcp: re-add header prediction","submitter":{"id":1025,"url":"http://patchwork.ozlabs.org/api/1.0/people/1025/?format=json","name":"Florian Westphal","email":"fw@strlen.de"},"series":[{"id":665,"url":"http://patchwork.ozlabs.org/api/1.0/series/665/?format=json","date":"2017-08-30T17:24:56","name":"tcp: re-add header prediction","version":1,"mbox":"http://patchwork.ozlabs.org/series/665/mbox/"}],"headers":{"Return-Path":"<netdev-owner@vger.kernel.org>","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=<UNKNOWN>)","Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xjC6y5QMpz9sN7\n\tfor <patchwork-incoming@ozlabs.org>;\n\tThu, 31 Aug 2017 03:24:42 +1000 (AEST)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1751947AbdH3RYl (ORCPT <rfc822;patchwork-incoming@ozlabs.org>);\n\tWed, 30 Aug 2017 13:24:41 -0400","from Chamillionaire.breakpoint.cc ([146.0.238.67]:35756 \"EHLO\n\tChamillionaire.breakpoint.cc\" rhost-flags-OK-OK-OK-OK)\n\tby vger.kernel.org with ESMTP id S1750972AbdH3RYk (ORCPT\n\t<rfc822;netdev@vger.kernel.org>); Wed, 30 Aug 2017 13:24:40 -0400","from fw by Chamillionaire.breakpoint.cc with local (Exim 4.84_2)\n\t(envelope-from <fw@breakpoint.cc>)\n\tid 1dn6gc-0007W0-S7; Wed, 30 Aug 2017 19:21:54 +0200"],"From":"Florian Westphal <fw@strlen.de>","To":"<netdev@vger.kernel.org>","Cc":"edumazet@google.com","Subject":"[PATCH net-next 0/2] tcp: re-add header prediction","Date":"Wed, 30 Aug 2017 19:24:56 +0200","Message-Id":"<20170830172458.18544-1-fw@strlen.de>","X-Mailer":"git-send-email 2.13.0","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"<netdev.vger.kernel.org>","X-Mailing-List":"netdev@vger.kernel.org"},"content":"Eric reported a performance regression caused by header prediction\nremoval.\n\nWe now call tcp_ack() much more frequently, for some workloads\nthis brings in enough cache line misses to become noticeable.\n\nWe could possibly still kill HP provided we find a different\nway to suppress unneeded tcp_ack, but given we're late in\nthe cycle it seems preferable to revert."}