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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F28C8C07E9D for ; Thu, 29 Sep 2022 08:52:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235144AbiI2IwH (ORCPT ); Thu, 29 Sep 2022 04:52:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234687AbiI2IwF (ORCPT ); Thu, 29 Sep 2022 04:52:05 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA99312ED89 for ; Thu, 29 Sep 2022 01:52:04 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 74B1B21B9B; Thu, 29 Sep 2022 08:52:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1664441523; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ffWNYmFzwrjWe/3G6b1ASR1aTachXTJ2+796fvJOEPg=; b=mkdGZEPVkeuo0nZiAXHPXQDBjcYkjILKqlyu9PP5fPa8TSAnOHSmaUh23EOcypGiMOU5zr DDYDaI+NAxcWMgEzb/nncqpFRieZveBnnEFS6G3W5BAhh/gzBzHL/Cb8P3+ruQ2/hFd0eY 5UyUpukd8tA7fPd22QRNxCs4VCWJLq4= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 58F652C146; Thu, 29 Sep 2022 08:51:56 +0000 (UTC) Date: Thu, 29 Sep 2022 10:52:02 +0200 From: Petr Mladek To: "Jason A. Donenfeld" Cc: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, Theodore Ts'o , Andy Shevchenko , John Ogness , Mike Galbraith , Peter Zijlstra , Rasmus Villemoes , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , Tejun Heo Subject: Re: [PATCH v4 2/2] lib/vsprintf: Initialize vsprintf's pointer hash once the random core is ready. Message-ID: References: <20220927104912.622645-1-bigeasy@linutronix.de> <20220927104912.622645-3-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2022-09-28 11:21:05, Jason A. Donenfeld wrote: > On 9/28/22, Sebastian Andrzej Siewior wrote: > > > >> I could replace "system_unbound_wq" with "system_wq" when > >> pushing. Is anybody against it, please? > > > > so schedule_delayed_work() then? yup. > > I don't mind at all. I used that one just because serialisation is not > > needed and neither is the CPU important. > > Indeed, given that this very much is unbound, I think Sebastian's > original patch makes most sense. Yes, the work does not need any specific CPU. The thing is that the normal system_wq is the preferred one. Any other workqueues should be used only when there is a particular reason for it. The unbound_wq should be used only when: + the work needs a lot of CPU time. + there are waves on related (sleeping) work items that might be triggered from different CPUs. In our case, the work is only one and short. The preferred system_wq is perfectly fine. Best Regards, Petr PS: It is not obvious. Tejun told me this when I converted a kthread into the workqueue API. Also I spent quite some time understanding the workqueue code recently.