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 C83951D86FF for ; Fri, 5 Sep 2025 16:42:53 +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=1757090573; cv=none; b=dHeWgHB+9tTub5ibckqhbVbLpDhQpRiaRNUJEgULQWNmLTOYEX32Gy9g0tlRIIy8vUId8ybNAMGtS5r9d2tquyxG4+3BM+icPhLTjhbsi0GxsBlvQAEGV9iirc36+vIwl4E10SNLnjXzfMIrbKWRhTTUqbAhXgy+73cDfg/PdDg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757090573; c=relaxed/simple; bh=wRUm2hwYPLI3a1cUGnowuCoYxvDFlUOcQoejEugtRzU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gxAf70qpHzcB57xHOzDmSnYK94kSSiQL96qvE32vzFrd4vQTyaYCILqkqabTr8nHZ5kT2soOfr+5yUn78qOJRXB0O1Rmxpio4nfrhaB9C10d0Iw6zWMacmoHGx9V+FoI/V2wYzp6vThT4e5ykwtG3tz7odgHIPJvyzadjd2ZmLE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YBo/Zn6L; 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="YBo/Zn6L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AC2EC4CEF1; Fri, 5 Sep 2025 16:42:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757090573; bh=wRUm2hwYPLI3a1cUGnowuCoYxvDFlUOcQoejEugtRzU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YBo/Zn6LplQPDTRKnETC3Ywms7EUCtiAjvMednwtMGAQ8B9cPzgBQWQOdTuB1Q/4j VO1vtzdTO6mGl/LlwUVnTHyXm0vLroB/42VleDvfNX+LgGiZHG7O6qx6WMYDS609UY YVjQPpWFe3b14tTYJId3Vy4SM0RbsqX6pzcB14Lk2jotwe7kAdLENusU2IyFiqGo2f Z43SdDB+o5saIlqxBXLwmUuvuPLt5NGcD8jC05v5vo/x1oEuO7l2ZkF72rY56ekYfU VZmfBP0cE5J22nV2Fe0zhBlo4T9tXC32VWRKKKu4n79zuzApXjpeJ0hu6HrI2JzHmH mzInJcrsgFxXA== Date: Fri, 5 Sep 2025 06:42:52 -1000 From: Tejun Heo To: Marco Crivellari Cc: linux-kernel@vger.kernel.org, Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Michal Hocko , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Subject: Re: [PATCH 1/1] sched: replace use of system_unbound_wq with system_dfl_wq Message-ID: References: <20250905090928.108703-1-marco.crivellari@suse.com> <20250905090928.108703-2-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=us-ascii Content-Disposition: inline In-Reply-To: <20250905090928.108703-2-marco.crivellari@suse.com> On Fri, Sep 05, 2025 at 11:09:28AM +0200, Marco Crivellari wrote: > Currently if a user enqueue a work item using schedule_delayed_work() the > used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use > WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to > schedule_work() that is using system_wq and queue_work(), that makes use > again of WORK_CPU_UNBOUND. > > This lack of consistentcy cannot be addressed without refactoring the API. > > system_unbound_wq should be the default workqueue so as not to enforce > locality constraints for random work whenever it's not required. > > Adding system_dfl_wq to encourage its use when unbound work should be used. > > queue_work() / queue_delayed_work() / mod_delayed_work() will now use the > new unbound wq: whether the user still use the old wq a warn will be > printed along with a wq redirect to the new one. > > The old system_unbound_wq will be kept for a few release cycles. > > Suggested-by: Tejun Heo > Signed-off-by: Marco Crivellari Acked-by: Tejun Heo Thanks. -- tejun