From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12192C433C1 for ; Mon, 22 Mar 2021 01:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D74A561937 for ; Mon, 22 Mar 2021 01:38:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229870AbhCVBhu (ORCPT ); Sun, 21 Mar 2021 21:37:50 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:3493 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229613AbhCVBhc (ORCPT ); Sun, 21 Mar 2021 21:37:32 -0400 Received: from DGGEML402-HUB.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4F3cWx3nwFzRSjD; Mon, 22 Mar 2021 09:35:41 +0800 (CST) Received: from dggpemm500005.china.huawei.com (7.185.36.74) by DGGEML402-HUB.china.huawei.com (10.3.17.38) with Microsoft SMTP Server (TLS) id 14.3.498.0; Mon, 22 Mar 2021 09:37:25 +0800 Received: from [127.0.0.1] (10.69.30.204) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2106.2; Mon, 22 Mar 2021 09:37:25 +0800 Subject: Re: [Linuxarm] [PATCH net] net: sched: fix packet stuck problem for lockless qdisc To: Cong Wang CC: David Miller , Jakub Kicinski , Vladimir Oltean , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eric Dumazet , Wei Wang , "Cong Wang ." , Taehee Yoo , "Linux Kernel Network Developers" , LKML , , Marc Kleine-Budde , , Jamal Hadi Salim , Jiri Pirko , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , , bpf , Jonas Bonn , Paolo Abeni , Michael Zhivich , Josh Hunt , "Jike Song" , Kehuan Feng , Ahmad Fatoum References: <1616050402-37023-1-git-send-email-linyunsheng@huawei.com> From: Yunsheng Lin Message-ID: <383f1c9b-016f-0aaa-def3-9d8786d40b01@huawei.com> Date: Mon, 22 Mar 2021 09:37:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.30.204] X-ClientProxiedBy: dggeme711-chm.china.huawei.com (10.1.199.107) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 2021/3/20 3:45, Cong Wang wrote: > On Fri, Mar 19, 2021 at 2:25 AM Yunsheng Lin wrote: >> I had done some performance test to see if there is value to >> fix the packet stuck problem and support lockless qdisc bypass, >> here is some result using pktgen in 'queue_xmit' mode on a dummy >> device as Paolo Abeni had done in [1], and using pfifo_fast qdisc: >> >> threads vanilla locked-qdisc vanilla+this_patch >> 1 2.6Mpps 2.9Mpps 2.5Mpps >> 2 3.9Mpps 4.8Mpps 3.6Mpps >> 4 5.6Mpps 3.0Mpps 4.7Mpps >> 8 2.7Mpps 1.6Mpps 2.8Mpps >> 16 2.2Mpps 1.3Mpps 2.3Mpps >> >> locked-qdisc: test by removing the "TCQ_F_NOLOCK | TCQ_F_CPUSTATS". > > I read this as this patch introduces somehow a performance > regression for -net, as the lockless bypass patch you submitted is > for -net-next. Yes, right now there is performance regression for fixing this bug, but the problem is that if we can not fix the above data race without any performance regression, do you prefer to send this patch to -net, or to -net-next with the lockless bypass patch? Any idea to fix this with less performance regression? > > Thanks. > > . >