From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64C2C25B69A for ; Wed, 7 May 2025 12:04:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746619500; cv=none; b=mmAliIoxi39JTrN+DK87cR7m4yMoR+D3ecIgInY7580eHd/me6z7OC3d0wqXjuNUtTGI3DzceDlhW3e6k6yHYuOWbE9xMRJJw9CR+BQjmQrV+R8EPpXbmBCNNef9UED+tHPBKiCeh/+O75wXgea6om+Z22oCLq0yfeca5T+qMTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746619500; c=relaxed/simple; bh=+PpCMUgk4FbEhoWXHklabVAaqaVKA5WyEg9bsqcLB8A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dLZhGtl4rwTqJFPze+eCCbuVZRV9vQkQCPgmDJxpqPfxEaLLaC/XhDizYsWW2Gp67tX0xW71Q6lgImg/AhOCfW/7bLUV7ckvGJ1iNkwoGFhwqcD7ruTgX6xUxdqVe6L6066hu9rzJsONXgJr9dESjZyLYbIBN5ks/RxZuOjB29M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mef40GdD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mef40GdD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1332FC4CEF6; Wed, 7 May 2025 12:04:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746619499; bh=+PpCMUgk4FbEhoWXHklabVAaqaVKA5WyEg9bsqcLB8A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mef40GdDEMZX/AzH/S0ZuqxQOp6MQRbj9HVTmnVbcmKx2g5vp6Kqy5Ie3994l+Yjl B62JPNIjF3/RnSDCpnoI+lk4zOAp/T1R69RtsR4GYtGtt4dyYJStR0tdQCSbFGzBaR +49vVQqjrJVRV2AGXS5/g5K/ELso8vAUarxlOQEOzP5IZe4PzWdJZqbXZUIBDM/Vzy gN2MK4Ql8K4YxwTQx4Ai8pcDEJghnVABTStsOHMG1Hex4f8G+tYI68MjYWiW0TWoZ3 VI2vftbBLwIqm/C5O8hQlxmojDBlNvAeYa0om9TvqP22MEuGUQGDbKTM9z/mN2O6Jq xHUtlhbxVvEDg== Date: Wed, 7 May 2025 14:04:55 +0200 From: Frederic Weisbecker To: Tejun Heo Cc: Marco Crivellari , linux-kernel@vger.kernel.org, Lai Jiangshan , Thomas Gleixner , Sebastian Andrzej Siewior Subject: Re: [PATCH 0/4] Workqueue: rename system workqueue and add WQ_PERCPU Message-ID: References: <20250503082834.49413-1-marco.crivellari@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Le Tue, May 06, 2025 at 02:42:26PM -1000, Tejun Heo a écrit : > On Tue, May 06, 2025 at 02:55:14PM +0200, Frederic Weisbecker wrote: > > Le Tue, May 06, 2025 at 12:10:18PM +0200, Marco Crivellari a écrit : > > > Hi, > > > > > > > Can you please make a summary of the discussion here? Referring to old > > > > thread is useful but it'd be nice to have the rationales laid out in the > > > > patchset - why this is desirable, what is the transition plan and what are > > > > the rationales for it? Also, please include a short summary in the patches. > > > > > > Sure, thanks for the advice. > > > > > > > Let's keep the old names for a release or two and trigger printk_once() > > > > warnings about the renames. These are pretty widely used, so I think it > > > > warrants a bit of extra effort. > > > > > > Good, sounds fine. > > > But I don't understand where printk_once() should be placed. > > > Can you give me some further guidance? > > > > So one possibility to achieve this is to not do a rename of system_wq > > to system_percpu_wq but eventually keep system_wq around and create the > > new system_percpu_wq. Convert all current users of system_wq to system_percpu_wq > > and warn from queue_work() when system_wq is used. > > > > I would personally prefer that we use WARN_ON_ONCE() so that this really > > gets noticed. Tejun what do you think? > > I'd stick with printk_once() at least for a while. There are systems set up > to panic on warnings and there will be a bunch of out-of-tree usages too. > Let's latch it up over multiple releases. Fair enough! Thanks. -- Frederic Weisbecker SUSE Labs