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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 93D49C433E0 for ; Thu, 4 Mar 2021 07:46:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 640DF64EFC for ; Thu, 4 Mar 2021 07:46:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233703AbhCDHqF (ORCPT ); Thu, 4 Mar 2021 02:46:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60362 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233035AbhCDHpf (ORCPT ); Thu, 4 Mar 2021 02:45:35 -0500 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90022C061574; Wed, 3 Mar 2021 23:44:55 -0800 (PST) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1lHifE-0007Ti-94; Thu, 04 Mar 2021 08:44:52 +0100 Date: Thu, 4 Mar 2021 08:44:52 +0100 From: Florian Westphal To: Mark Tomlinson Cc: pablo@netfilter.org, kadlec@netfilter.org, fw@strlen.de, netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] Revert "netfilter: x_tables: Switch synchronization to RCU" Message-ID: <20210304074452.GI17911@breakpoint.cc> References: <20210304013116.8420-1-mark.tomlinson@alliedtelesis.co.nz> <20210304013116.8420-3-mark.tomlinson@alliedtelesis.co.nz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210304013116.8420-3-mark.tomlinson@alliedtelesis.co.nz> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Mark Tomlinson wrote: > This reverts commit cc00bcaa589914096edef7fb87ca5cee4a166b5c. > > This (and the preceding) patch basically re-implemented the RCU > mechanisms of patch 784544739a25. That patch was replaced because of the > performance problems that it created when replacing tables. Now, we have > the same issue: the call to synchronize_rcu() makes replacing tables > slower by as much as an order of magnitude. Can you give roigh numbers? > See https://lore.kernel.org/patchwork/patch/151796/ for why using RCU is > not a good idea. Please, no link.