From patchwork Mon Feb 8 19:34:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Wang X-Patchwork-Id: 379894 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham 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 AA175C433DB for ; Mon, 8 Feb 2021 19:37:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A33664DDD for ; Mon, 8 Feb 2021 19:37:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236365AbhBHThM (ORCPT ); Mon, 8 Feb 2021 14:37:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236234AbhBHTfH (ORCPT ); Mon, 8 Feb 2021 14:35:07 -0500 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04055C0617A9 for ; Mon, 8 Feb 2021 11:34:18 -0800 (PST) Received: by mail-qk1-x74a.google.com with SMTP id x18so5814319qki.2 for ; Mon, 08 Feb 2021 11:34:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=lyNvFzLMOm6Vlunzw+chJzXZCFsEIptRnlpon2EJ7QE=; b=D71Zn6vuK8XSlgxDzvRcEJQl4Ibd6KtdKQeHiwNak5jL5Hy6YXscqQXfPiAwzI4dBk MGmCXys+LDyB1DSCJG/IGgXacfru34iy07yhfF1uQzK+TU7HJ//22SjpsO6FIvGSHg3L OO0mXoHC4CITBM0vEu9GIUGk/gvugo23FjGJeciKxVgfL6cTb1ST43SkmoLJvyP0NbUK v2rVXRPI/05hmrQTFYpGPlEo+eWXfLnauX0qUJbC+jw6XAsx8juovXX8owcBSJ1eKscm 5wDuS6227EtPCiVW/kzAyUyoSw5qvpbULNZkVGxAmVY/iVlfPM0YxkrZLNL4HywkraVp EFVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=lyNvFzLMOm6Vlunzw+chJzXZCFsEIptRnlpon2EJ7QE=; b=az3ZyQxxD12KU8qvvb/QuFlcvSJ7thl9+8Wo1O80/p8iEn57gaiiVVsuGtHogvYhv5 K4n0AfikJGRvLHOAFP1FVDDaalW7VsfLM6Sw4Xf0eZDyLbLphHOJCELjH8fHDmaTUwb+ AuUpqCgjeXos+uaTiXjrj2QsOtnFvAx7504ZDpjw3WJXl7xCbeq8bI7d6gaN7/kpLC9c 9zv0TJm69U1J+YkdbWQ7HCvBbeGA8JrsKp3cYPRUmzc/zqZIRnrGH+VzLox4+E+rgjpc aX2krE2DQ5S3kI8bfrE5tSVJHtgtrIjHqSaZlAxdV48DJM8oihnk3DEQTmXpMDwIAbsp zJoA== X-Gm-Message-State: AOAM531qRN/W0TYAd0pdZnVSh6uK1yYhaMqog9x4nnZxuz+cS1FuthNm 7PQhOVZKZRKAphxL0Fa2t0vmlPM7Wuw= X-Google-Smtp-Source: ABdhPJyoHBuestLi2dUzbpIEFWD/NQC6hlVGGNAgyvsKzrZAXn3lpS/oj+1Lt+9nWMCJJ++S7iTXYBjhY/s= Sender: "weiwan via sendgmr" X-Received: from weiwan.svl.corp.google.com ([2620:15c:2c4:201:35a9:bca1:5bb0:4132]) (user=weiwan job=sendgmr) by 2002:a0c:f94a:: with SMTP id i10mr17801668qvo.22.1612812857196; Mon, 08 Feb 2021 11:34:17 -0800 (PST) Date: Mon, 8 Feb 2021 11:34:10 -0800 In-Reply-To: <20210208193410.3859094-1-weiwan@google.com> Message-Id: <20210208193410.3859094-4-weiwan@google.com> Mime-Version: 1.0 References: <20210208193410.3859094-1-weiwan@google.com> X-Mailer: git-send-email 2.30.0.478.g8a0d178c01-goog Subject: [PATCH net-next v11 3/3] net: add sysfs attribute to control napi threaded mode From: Wei Wang To: "David S . Miller" , Jakub Kicinski , netdev@vger.kernel.org Cc: Eric Dumazet , Paolo Abeni , Hannes Frederic Sowa , Alexander Duyck , Felix Fietkau Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch adds a new sysfs attribute to the network device class. Said attribute provides a per-device control to enable/disable the threaded mode for all the napi instances of the given network device, without the need for a device up/down. User sets it to 1 or 0 to enable or disable threaded mode. Note: when switching between threaded and the current softirq based mode for a napi instance, it will not immediately take effect if the napi is currently being polled. The mode switch will happen for the next time napi_schedule() is called. Co-developed-by: Paolo Abeni Signed-off-by: Paolo Abeni Co-developed-by: Hannes Frederic Sowa Signed-off-by: Hannes Frederic Sowa Co-developed-by: Felix Fietkau Signed-off-by: Felix Fietkau Signed-off-by: Wei Wang --- Documentation/ABI/testing/sysfs-class-net | 15 +++++++ include/linux/netdevice.h | 2 + net/core/dev.c | 48 ++++++++++++++++++++++- net/core/net-sysfs.c | 40 +++++++++++++++++++ 4 files changed, 103 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net index 1f2002df5ba2..1419103d11f9 100644 --- a/Documentation/ABI/testing/sysfs-class-net +++ b/Documentation/ABI/testing/sysfs-class-net @@ -337,3 +337,18 @@ Contact: netdev@vger.kernel.org Description: 32-bit unsigned integer counting the number of times the link has been down + +What: /sys/class/net//threaded +Date: Jan 2021 +KernelVersion: 5.12 +Contact: netdev@vger.kernel.org +Description: + Boolean value to control the threaded mode per device. User could + set this value to enable/disable threaded mode for all napi + belonging to this device, without the need to do device up/down. + + Possible values: + == ================================== + 0 threaded mode disabled for this dev + 1 threaded mode enabled for this dev + == ================================== diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 99fb4ec9573e..1340327f7abf 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -497,6 +497,8 @@ static inline bool napi_complete(struct napi_struct *n) return napi_complete_done(n, 0); } +int dev_set_threaded(struct net_device *dev, bool threaded); + /** * napi_disable - prevent NAPI from scheduling * @n: NAPI context diff --git a/net/core/dev.c b/net/core/dev.c index 1e35f4f44f3b..7647278e46f0 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4291,8 +4291,9 @@ static inline void ____napi_schedule(struct softnet_data *sd, if (test_bit(NAPI_STATE_THREADED, &napi->state)) { /* Paired with smp_mb__before_atomic() in - * napi_enable(). Use READ_ONCE() to guarantee - * a complete read on napi->thread. Only call + * napi_enable()/dev_set_threaded(). + * Use READ_ONCE() to guarantee a complete + * read on napi->thread. Only call * wake_up_process() when it's not NULL. */ thread = READ_ONCE(napi->thread); @@ -6738,6 +6739,49 @@ static void init_gro_hash(struct napi_struct *napi) napi->gro_bitmask = 0; } +int dev_set_threaded(struct net_device *dev, bool threaded) +{ + struct napi_struct *napi; + int err = 0; + + if (dev->threaded == threaded) + return 0; + + if (threaded) { + list_for_each_entry(napi, &dev->napi_list, dev_list) { + if (!napi->thread) { + err = napi_kthread_create(napi); + if (err) { + threaded = false; + break; + } + } + } + } + + dev->threaded = threaded; + + /* Make sure kthread is created before THREADED bit + * is set. + */ + smp_mb__before_atomic(); + + /* Setting/unsetting threaded mode on a napi might not immediately + * take effect, if the current napi instance is actively being + * polled. In this case, the switch between threaded mode and + * softirq mode will happen in the next round of napi_schedule(). + * This should not cause hiccups/stalls to the live traffic. + */ + list_for_each_entry(napi, &dev->napi_list, dev_list) { + if (threaded) + set_bit(NAPI_STATE_THREADED, &napi->state); + else + clear_bit(NAPI_STATE_THREADED, &napi->state); + } + + return err; +} + void netif_napi_add(struct net_device *dev, struct napi_struct *napi, int (*poll)(struct napi_struct *, int), int weight) { diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index daf502c13d6d..e72d474c2623 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -538,6 +538,45 @@ static ssize_t phys_switch_id_show(struct device *dev, } static DEVICE_ATTR_RO(phys_switch_id); +static ssize_t threaded_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct net_device *netdev = to_net_dev(dev); + ssize_t ret = -EINVAL; + + if (!rtnl_trylock()) + return restart_syscall(); + + if (dev_isalive(netdev)) + ret = sprintf(buf, fmt_dec, netdev->threaded); + + rtnl_unlock(); + return ret; +} + +static int modify_napi_threaded(struct net_device *dev, unsigned long val) +{ + int ret; + + if (list_empty(&dev->napi_list)) + return -EOPNOTSUPP; + + if (val != 0 && val != 1) + return -EOPNOTSUPP; + + ret = dev_set_threaded(dev, val); + + return ret; +} + +static ssize_t threaded_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + return netdev_store(dev, attr, buf, len, modify_napi_threaded); +} +static DEVICE_ATTR_RW(threaded); + static struct attribute *net_class_attrs[] __ro_after_init = { &dev_attr_netdev_group.attr, &dev_attr_type.attr, @@ -570,6 +609,7 @@ static struct attribute *net_class_attrs[] __ro_after_init = { &dev_attr_proto_down.attr, &dev_attr_carrier_up_count.attr, &dev_attr_carrier_down_count.attr, + &dev_attr_threaded.attr, NULL, }; ATTRIBUTE_GROUPS(net_class);