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 1CC32CDB474 for ; Tue, 17 Oct 2023 14:11:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343890AbjJQOLR (ORCPT ); Tue, 17 Oct 2023 10:11:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233670AbjJQOLP (ORCPT ); Tue, 17 Oct 2023 10:11:15 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43DDEF0 for ; Tue, 17 Oct 2023 07:11:14 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6F0FC433C8; Tue, 17 Oct 2023 14:11:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697551873; bh=C+zGadaHwfOd74zIWHTHTzMU6aRU34ew/PXDW8ogT5w=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=tugooydZmUt5cJGnJ6rQmHx8hq0BedzTJK2w+XwhNQypjTYFQbBZYP04G4vOEf8mx Q8JWv+5o984m/LEuPmU0xcWyYtOxPpXWReczc3runKKsUsbVTyeZI/c2HkIZan3YUF fyUZ6cUSYUexU0gsTPbK4YuF4BXs7ZN7GA72c+LmmptccLWFmkbOCPo9Sgg+4vKVm4 AQ1MHmjcXvyMiG19gxe4ePWDXm6HR+VinUSypeZ40Cqzlf0rCk4NS2wA8qlH5w9a/C hvk1Q1Oi99JVDfYVzsjBbKUvZj2aXEMFTbKWT2jdDIzCvGnSWODYOnANQC8eXghaqs tEt/LVdcyRN5A== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 98B56CE03B0; Tue, 17 Oct 2023 07:11:13 -0700 (PDT) Date: Tue, 17 Oct 2023 07:11:13 -0700 From: "Paul E. McKenney" To: Thomas Gleixner Cc: John Stultz , Tetsuo Handa , Stephen Boyd , LKML , Sebastian Andrzej Siewior , x86@kernel.org Subject: Re: [PATCH] clocksource: disable irq when holding watchdog_lock. Message-ID: Reply-To: paulmck@kernel.org References: <80ff5036-8449-44a6-ba2f-0130d3be6b57@I-love.SAKURA.ne.jp> <878r826xys.ffs@tglx> <8734y97ng5.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8734y97ng5.ffs@tglx> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 17, 2023 at 08:49:46AM +0200, Thomas Gleixner wrote: > On Mon, Oct 16 2023 at 16:03, Paul E. McKenney wrote: > > On Mon, Oct 16, 2023 at 11:47:55PM +0200, Thomas Gleixner wrote: > >> That said, this whole clocksource watchdog mess wants a proper > >> overhaul. It has become a pile of warts and duct tape by now and after > >> staring at it long enough there is no real reason to run it in a timer > >> callback anymore. It just can move into delayed work and the whole > >> locking problem can be reduced to the clocksource_mutex and some well > >> thought out atomic operations to handle the mark unstable case. But > >> that's a different story and not relevant for curing the problem at > >> hand. > > > > Moving the code to delayed work seems quite reasonable. > > > > But Thomas, you do understand that the way things have been going for > > the clocksource watchdog, pushing it out to delayed work will no doubt > > add yet more hair on large busy systems, right? Yeah, yeah, I know, > > delayed work shouldn't be any worse than ksoftirqd. The key word of > > course being "shouldn't". ;-) > > Yes, I'm aware of that. I still think it's worth at least to try it. OK, good. And again, agreed. Thanx, Paul