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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 0EEB3C43464 for ; Fri, 18 Sep 2020 00:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4A8F20789 for ; Fri, 18 Sep 2020 00:02:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=networkplumber-org.20150623.gappssmtp.com header.i=@networkplumber-org.20150623.gappssmtp.com header.b="hsbyNOmN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726236AbgIRACN (ORCPT ); Thu, 17 Sep 2020 20:02:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726117AbgIRACM (ORCPT ); Thu, 17 Sep 2020 20:02:12 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD6F7C06174A for ; Thu, 17 Sep 2020 17:02:12 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id jw11so2053071pjb.0 for ; Thu, 17 Sep 2020 17:02:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/Z6/uk13fDdDtxzok5bqvhcNjwfgQSfjItx45RAkKMM=; b=hsbyNOmNnu+3dyU50HMPOINq4tVVRyHudxgOhWxe4IOJlFnaIC9FCiM+bC0ZcI/Akk VUSzXPk2hc/0qRqxyvt4ivB+71QU4yuBzD8zkngQg6bCqFCiw94eQbxZMRpbMTgAsFNt jHtkzEEt5TJgQ1ZHYWWZcVsaz3FYnpls9py69nYJJN+1lhqNr6op4zF4Ch4xl4G6XTNs 3C60yRDAghia+qJVohd78KAYk7wRrdmAdX80qll/P86Anb5y71VDJ8HWgUTzhEumWwcB NL+NoGnzRH4Kg/T6jRZ3ynx/dw4lr8P72jVu8m8HXobN7pccHHcMuP8J4eO9iIZN/xCd sdzA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=/Z6/uk13fDdDtxzok5bqvhcNjwfgQSfjItx45RAkKMM=; b=XKIF0noL8Umv0zsAkCZppcncipCbh2LUdtz7vSSvgZSHsNeJGp6Fx4OqSZcVIAbLJm gk6ZLPkoFRX5zvQ8EfVYX+NGX4NuRCfBRJdRNWCY5bhu4s8NjI3BYFfYLmsTya4fx1m7 4fLPzZxPbgKFbLilfLnb3h8Knh+uzB6rt1qmN+dzGLZzsgIT/1/Z4gj65BLjMinb/sHs UMVnbBBy1a5Plx5mHBDlHLRvltCMzFXRiXzGAjstd7uO4hhFBnZHaTTwbhQK9DcMYQC2 F5v0rZGUtxrCXQcdSiwx2tdZHKNy+6eWxFJ8bIQF3JaSwI5PXi7IKF4U4RI8NIQEMhzW eK3w== X-Gm-Message-State: AOAM5328gp9feANx99EKhqkSPz2K/lDmZ/E2vz9KsK8fX8YYVcmkxpLb CzKUDs898hsqfhuvrUA5EW0abA== X-Google-Smtp-Source: ABdhPJwQp2qR21KZabTeKaqQ56ZDW9ZR64gwodC+vJPyOYuI3+yKcUAEIuLEVY70q4dA9tJ1lJbS5g== X-Received: by 2002:a17:90a:fc6:: with SMTP id 64mr11048059pjz.194.1600387332194; Thu, 17 Sep 2020 17:02:12 -0700 (PDT) Received: from hermes.lan (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id 16sm749246pjl.27.2020.09.17.17.02.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2020 17:02:11 -0700 (PDT) Date: Thu, 17 Sep 2020 17:02:03 -0700 From: Stephen Hemminger To: fruggeri@arista.com (Francesco Ruggeri) Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, xiyou.wangcong@gmail.com, ap420073@gmail.com, andriin@fb.com, edumazet@google.com, jiri@mellanox.com, ast@kernel.org, kuba@kernel.org, davem@davemloft.net Subject: Re: [PATCH v3] net: use exponential backoff in netdev_wait_allrefs Message-ID: <20200917170203.1a363082@hermes.lan> In-Reply-To: <20200917234953.CB1D295C0A69@us180.sjc.aristanetworks.com> References: <20200917234953.CB1D295C0A69@us180.sjc.aristanetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 17 Sep 2020 16:49:53 -0700 fruggeri@arista.com (Francesco Ruggeri) wrote: > The combination of aca_free_rcu, introduced in commit 2384d02520ff > ("net/ipv6: Add anycast addresses to a global hashtable"), and > fib6_info_destroy_rcu, introduced in commit 9b0a8da8c4c6 ("net/ipv6: > respect rcu grace period before freeing fib6_info"), can result in > an extra rcu grace period being needed when deleting an interface, > with the result that netdev_wait_allrefs ends up hitting the msleep(250), > which is considerably longer than the required grace period. > This can result in long delays when deleting a large number of interfaces, > and it can be observed with this script: > Is there anyway to make RCU trigger faster?