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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 D5C4CC10F13 for ; Mon, 8 Apr 2019 15:10:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A43D021473 for ; Mon, 8 Apr 2019 15:10:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554736242; bh=EKpT785ZLjUmMCMjDY46/ivjsr8FzlRFFl9usJre3lQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=HwXoscg/QFaf2qRl8deasdCVtFoKCZH7GV9Ritj54xqKQqWWk9rPsL4PALlF8cRRN K6xQNRwnwpJ6OozfasndO5zD9ALDtBEESz69HvLI/kWDsUgVAo123DB+C+hH7OCmFT qzajqELvdywb+tCI1dLSvmzO0rIt6Btqbm9z2+gQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728659AbfDHPKl (ORCPT ); Mon, 8 Apr 2019 11:10:41 -0400 Received: from mail-yb1-f193.google.com ([209.85.219.193]:32996 "EHLO mail-yb1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726716AbfDHPKl (ORCPT ); Mon, 8 Apr 2019 11:10:41 -0400 Received: by mail-yb1-f193.google.com with SMTP id i10so5294919ybk.0 for ; Mon, 08 Apr 2019 08:10:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=9m4FOQLfq7QfTKu/uMXz/CdulaGpOhzU3DCk+O7A7Xg=; b=pN+HkcLnV8ezBOW1/NsYLNwrJxtlO/qc4IIPyzFdhmcUWnfkXggQ7Xp+b0tas9V+fh Y10NgLybZkPZNOfwdVIoV+i6jx2kV3qInL49aVAeSazFG8Vyby3YVjkEokkSLphQC56G aEPR+pM9+rHX5qtf+eb3h0ks7Nw9TvUSlH4qWNQ7og/sFqHKUxJ2aCkwvQQ8x+XNf3Cn lF+DCpY+4T7994iUvZWbviLxfnZs31RYCRE5AqCjA7tUasXDopBUMClc0KXD6DxkL8FW kRJt0biVb0qPK/iib/WY9xLlPyPIZObe3KGbVxExoEHu869sljGa4skUlU1iBQVt2AZM rsSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=9m4FOQLfq7QfTKu/uMXz/CdulaGpOhzU3DCk+O7A7Xg=; b=XGF6Fui9VnFcKbYctdXIqwmVxjpBF6Wa+7YOiVvnGkVbUhx0qwIvzH916b58TMS7GE ThyzbDMMyW/oq1C9IBLryi00RpnHimOqekLUg6sK4K9+RJbNX8SrEidWvOW8uPkrbRWL laWLclIkBm9J1svdueg7aeZkg7MbE70Ko09eZ7Qa3+QvaWJ1Nf5/LgvHrkIq7k84BJ1D rRoQOrM5pBnrclHslDxDexSJz+t5ENzXJHrEskoiwc/9PcsAXC1VgBXhwsknjuYtu9Va 7UquXMsL0pQEuQszcZvzOlFSmPuGqhtTC4XkpI+yMiL7Gh3LcBaAmaN+UOwI3DRY09c5 ANXw== X-Gm-Message-State: APjAAAVGG+NrEHlVDX3TCxWmVSz5Z4qqyi3LZgFkGhvx3TQyTHDq1CGd XB8cwwM6+xHaTu9kGq/1zJ4= X-Google-Smtp-Source: APXvYqzyC6L4oXjjyLLMrTIPMzcyInhtygGxy5lMNqxtJUBmyjyunnG0fL8zAk0xfSg3i1kVNwmnlQ== X-Received: by 2002:a25:81c9:: with SMTP id n9mr5893691ybm.246.1554736240054; Mon, 08 Apr 2019 08:10:40 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::3:135c]) by smtp.gmail.com with ESMTPSA id l82sm10590289ywl.6.2019.04.08.08.10.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Apr 2019 08:10:39 -0700 (PDT) Date: Mon, 8 Apr 2019 08:10:37 -0700 From: Tejun Heo To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Lai Jiangshan , Ingo Molnar , Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH 1/2] workqueue: Use normal rcu Message-ID: <20190408151037.GH1975820@devbig004.ftw2.facebook.com> References: <20190313165548.19713-1-bigeasy@linutronix.de> <20190313165548.19713-2-bigeasy@linutronix.de> <20190321205935.7ndo5k5zumc77h37@linutronix.de> <20190322174334.GC69236@devbig004.ftw2.facebook.com> <20190322175923.5o6y53yiseo3phif@linutronix.de> <20190405144218.gvfft6aw36ciogfi@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190405144218.gvfft6aw36ciogfi@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Sebastian. On Fri, Apr 05, 2019 at 04:42:18PM +0200, Sebastian Andrzej Siewior wrote: > On 2019-03-22 18:59:23 [+0100], To Tejun Heo wrote: > > On 2019-03-22 10:43:34 [-0700], Tejun Heo wrote: > > > Hello, > Hi, > > > > We can switch but it doesn't really say why we'd want to. Can you > > > please explain why this is better? > > > > there is this undocumented part. Avoiding the sched RCU means also we > > are more preemptible which is good :) Especially on -RT where we can't > > disable preemption across the whole critical section. > > > > Is this good enough? > > a gentle ping. Heh, yeah, sorry about dragging my feet on it. The patchset itself doesn't actually improve the upstream kernel (except for the obvious bug fix where it's using the wrong call_rcu right now), so I've been constantly on the fence. At the same time, it doesn't really worsen anything either. Imma look through the patches once more later today. Thanks. -- tejun