Cover Letter Detail

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{
    "id": 807774,
    "url": "http://patchwork.ozlabs.org/api/covers/807774/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/netdev/cover/20170830172458.18544-1-fw@strlen.de/",
    "project": {
        "id": 7,
        "url": "http://patchwork.ozlabs.org/api/projects/7/?format=api",
        "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,
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        "list_archive_url_format": "",
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    },
    "msgid": "<20170830172458.18544-1-fw@strlen.de>",
    "list_archive_url": null,
    "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/people/1025/?format=api",
        "name": "Florian Westphal",
        "email": "fw@strlen.de"
    },
    "mbox": "http://patchwork.ozlabs.org/project/netdev/cover/20170830172458.18544-1-fw@strlen.de/mbox/",
    "series": [
        {
            "id": 665,
            "url": "http://patchwork.ozlabs.org/api/series/665/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/netdev/list/?series=665",
            "date": "2017-08-30T17:24:56",
            "name": "tcp: re-add header prediction",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/665/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/covers/807774/comments/",
    "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."
}