From patchwork Wed Sep 30 19:21:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Wang X-Patchwork-Id: 259813 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=-21.1 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 4D269C4727C for ; Wed, 30 Sep 2020 19:22:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 064BA2071E for ; Wed, 30 Sep 2020 19:22:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Y2I3C0RC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730117AbgI3TWh (ORCPT ); Wed, 30 Sep 2020 15:22:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbgI3TWh (ORCPT ); Wed, 30 Sep 2020 15:22:37 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5569C061755 for ; Wed, 30 Sep 2020 12:22:36 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id d20so1519936plr.18 for ; Wed, 30 Sep 2020 12:22:36 -0700 (PDT) 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=q0P1tSMlNAWIV7zQIDv2HdEMyoD3KRTuWxJZUM97nVU=; b=Y2I3C0RCK6Hx5PXS6nbwME5Pvk1+4meeGGrm/v21y0zr4shYRlAZOsphdLF8wNwg9l N5a/lQ6DAko9cFZTCHzfuSeD638v3BV7zSmha7G7xwyr33divE0ZyAVcZZRuWihjXpXX BpX3/+4dmLzxjjvHBVOeUPYDKPfXFzVl3jTdOxOc/muAi6YKXxsllNUXlwZD4VeW82J4 cFCSpiwpRlsl7ZW94qiaxqBDzvGUyWVwuO1oBegX0q4ur6x/Fizkux9jU990LdRtepLq Zxn71aX+PKh9+tSB4aaLUxeuhyQgKS6MKv/lev5P69NqYPW/1slpUBfBlHViXbS1Zo8X 4vBg== 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=q0P1tSMlNAWIV7zQIDv2HdEMyoD3KRTuWxJZUM97nVU=; b=QcR6EeNWAd2vM41VPYIL8uiQmlOBgw/WjpzQoecavAj2hUb3Biz5CkSVON9nQg7sYX NltkFobB9YZgOyxIXKzTuEuLfbCGdp4fy7pUBwBmgwWS/AN9B8rRiLuomsAZRelzkBvM klVsqfxeIObIIK8SdmlUQogoa9NH6gwxpQdki+2MRgldDZU0CBRtuhp1T9LbdTXD7g7z aRyof7y2hFP4+/HkE9xc23Lp1gOCQODDFmbxrcYAoQE/PsOXOrXnMig5Ku5p0HtR9rZY bTMK+t93G22AwZ/3AvLSbqJpRljLabK9o90pWzrHXG38eS4J669jo+PUfOeqzR+3CXtK uYbw== X-Gm-Message-State: AOAM533iK7jbwlJkhfJFHXTW9Dp7Cl3CSiRVWLTAHJjR5dO87ILEpz0p thWwRY8HcFxQKgEcqnGvlSX0quJVKhg= X-Google-Smtp-Source: ABdhPJzsjnyILZ8+Xe9eHao7/1qdUQkUum8OCbGs+2flAKvowDAZdkEI876QVRQXgB0rRm24MDSwVDvfs4A= Sender: "weiwan via sendgmr" X-Received: from weiwan.svl.corp.google.com ([2620:15c:2c4:201:1ea0:b8ff:fe75:cf08]) (user=weiwan job=sendgmr) by 2002:a65:5185:: with SMTP id h5mr3325872pgq.37.1601493756340; Wed, 30 Sep 2020 12:22:36 -0700 (PDT) Date: Wed, 30 Sep 2020 12:21:39 -0700 In-Reply-To: <20200930192140.4192859-1-weiwan@google.com> Message-Id: <20200930192140.4192859-5-weiwan@google.com> Mime-Version: 1.0 References: <20200930192140.4192859-1-weiwan@google.com> X-Mailer: git-send-email 2.28.0.709.gb0816b6eb0-goog Subject: [PATCH net-next 4/5] net: modify kthread handler to use __napi_poll() From: Wei Wang To: "David S . Miller" , netdev@vger.kernel.org Cc: Eric Dumazet , Jakub Kicinski , Hannes Frederic Sowa , Paolo Abeni , Felix Fietkau , Wei Wang Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Jakub Kicinski The current kthread handler calls napi_poll() and has to pass a dummy repoll list to the function, which seems redundent. The new proposed kthread handler calls the newly proposed __napi_poll(), and respects napi->weight as before. If repoll is needed, cond_resched() is called first to give other tasks a chance to run before repolling. This change is proposed by Jakub Kicinski on top of the previous patch. Signed-off-by: Jakub Kicinski Signed-off-by: Wei Wang --- net/core/dev.c | 62 +++++++++++++++++++------------------------------- 1 file changed, 24 insertions(+), 38 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index c82522262ca8..b4f33e442b5e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6827,6 +6827,15 @@ static int __napi_poll(struct napi_struct *n, bool *repoll) gro_normal_list(n); + /* Some drivers may have called napi_schedule + * prior to exhausting their budget. + */ + if (unlikely(!list_empty(&n->poll_list))) { + pr_warn_once("%s: Budget exhausted after napi rescheduled\n", + n->dev ? n->dev->name : "backlog"); + return work; + } + *repoll = true; return work; @@ -6847,15 +6856,6 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll) if (!do_repoll) goto out_unlock; - /* Some drivers may have called napi_schedule - * prior to exhausting their budget. - */ - if (unlikely(!list_empty(&n->poll_list))) { - pr_warn_once("%s: Budget exhausted after napi rescheduled\n", - n->dev ? n->dev->name : "backlog"); - goto out_unlock; - } - list_add_tail(&n->poll_list, repoll); out_unlock: @@ -6884,40 +6884,26 @@ static int napi_thread_wait(struct napi_struct *napi) static int napi_threaded_poll(void *data) { struct napi_struct *napi = data; + void *have; while (!napi_thread_wait(napi)) { - struct list_head dummy_repoll; - int budget = netdev_budget; - unsigned long time_limit; - bool again = true; + for (;;) { + bool repoll = false; - INIT_LIST_HEAD(&dummy_repoll); - local_bh_disable(); - time_limit = jiffies + 2; - do { - /* ensure that the poll list is not empty */ - if (list_empty(&dummy_repoll)) - list_add(&napi->poll_list, &dummy_repoll); - - budget -= napi_poll(napi, &dummy_repoll); - if (unlikely(budget <= 0 || - time_after_eq(jiffies, time_limit))) { - cond_resched(); - - /* refresh the budget */ - budget = netdev_budget; - __kfree_skb_flush(); - time_limit = jiffies + 2; - } + local_bh_disable(); - if (napi_disable_pending(napi)) - again = false; - else if (!test_bit(NAPI_STATE_SCHED, &napi->state)) - again = false; - } while (again); + have = netpoll_poll_lock(napi); + __napi_poll(napi, &repoll); + netpoll_poll_unlock(have); - __kfree_skb_flush(); - local_bh_enable(); + __kfree_skb_flush(); + local_bh_enable(); + + if (!repoll) + break; + + cond_resched(); + } } return 0; }