From patchwork Thu Jun 3 01:47:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 454644 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 E3485C4708F for ; Thu, 3 Jun 2021 01:48:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD1EB613DC for ; Thu, 3 Jun 2021 01:48:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229947AbhFCBuL (ORCPT ); Wed, 2 Jun 2021 21:50:11 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:3518 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229833AbhFCBuB (ORCPT ); Wed, 2 Jun 2021 21:50:01 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4FwTHY2Q10zZcBy; Thu, 3 Jun 2021 09:45:29 +0800 (CST) Received: from dggpemm500005.china.huawei.com (7.185.36.74) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 3 Jun 2021 09:48:13 +0800 Received: from localhost.localdomain (10.69.192.56) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 3 Jun 2021 09:48:13 +0800 From: Yunsheng Lin To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH net-next v2 1/3] net: sched: avoid unnecessary seqcount operation for lockless qdisc Date: Thu, 3 Jun 2021 09:47:58 +0800 Message-ID: <1622684880-39895-2-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1622684880-39895-1-git-send-email-linyunsheng@huawei.com> References: <1622684880-39895-1-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.69.192.56] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org qdisc->running seqcount operation is mainly used to do heuristic locking on q->busylock for locked qdisc, see qdisc_is_running() and __dev_xmit_skb(). So avoid doing seqcount operation for qdisc with TCQ_F_NOLOCK flag. Signed-off-by: Yunsheng Lin --- include/net/sch_generic.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 1e62551..3ed6bcc 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -188,6 +188,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) nolock_empty: WRITE_ONCE(qdisc->empty, false); + return true; } else if (qdisc_is_running(qdisc)) { return false; } @@ -201,7 +202,6 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) static inline void qdisc_run_end(struct Qdisc *qdisc) { - write_seqcount_end(&qdisc->running); if (qdisc->flags & TCQ_F_NOLOCK) { spin_unlock(&qdisc->seqlock); @@ -210,6 +210,8 @@ static inline void qdisc_run_end(struct Qdisc *qdisc) clear_bit(__QDISC_STATE_MISSED, &qdisc->state); __netif_schedule(qdisc); } + } else { + write_seqcount_end(&qdisc->running); } }