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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CD153C2D0DB for ; Sat, 25 Jan 2020 20:19:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9160120716 for ; Sat, 25 Jan 2020 20:19:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="bMl/02vp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727479AbgAYUTL (ORCPT ); Sat, 25 Jan 2020 15:19:11 -0500 Received: from mail.skyhub.de ([5.9.137.197]:37680 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726454AbgAYUTL (ORCPT ); Sat, 25 Jan 2020 15:19:11 -0500 Received: from zn.tnic (p200300EC2F1CE900698071F6EB5AEF0D.dip0.t-ipconnect.de [IPv6:2003:ec:2f1c:e900:6980:71f6:eb5a:ef0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id BEFC91EC0AA0; Sat, 25 Jan 2020 21:19:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1579983549; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=GWPlkscBO5mlHw1+EDfCxlwtI5gheQRnpKKvPRbkm3o=; b=bMl/02vpaWe3auQVAi7TYHf+H47CENvzT6PRhVayXhI4THOoROdaKBOXsOP3YTOXNZc0+U Lpsphk4RWdBuLwrg+G4YjUex4/7xogRaXML4EkclGjOReRLWELixYsA0R2znOjfLWrfdL7 T4m0ZBme5GoxPH6FSrLBCilSTTzjo8s= Date: Sat, 25 Jan 2020 21:19:05 +0100 From: Borislav Petkov To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, x86 Subject: Re: [tip: core/rcu] rcu: Enable tick for nohz_full CPUs slow to provide expedited QS Message-ID: <20200125201904.GB4369@zn.tnic> References: <157994897654.396.5667707782512768142.tip-bot2@tip-bot2> <20200125131425.GB16136@zn.tnic> <20200125161050.GE2935@paulmck-ThinkPad-P72> <20200125175442.GA4369@zn.tnic> <20200125194846.GF2935@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200125194846.GF2935@paulmck-ThinkPad-P72> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 25, 2020 at 11:48:46AM -0800, Paul E. McKenney wrote: > My guess is "no" because the real-time application would not yet be > running during boot. On the other hand, if this issue is due not so much > to boot, but to (say) expensive filesystem operations on large systems, > that might be a different story. Possible - that warn happened around a btrfs init-something. > Except that I would have hard questions to ask of someone doing expensive > filesystem operations while their deep-sub-millisecond real-time > application was running. So even then, I doubt that they would care. > > Again, if I am wrong about this, this would be an excellent time for > them to let me know. I can see the hint there. :-) > In the meantime, one question... Are you testing for realtime suitability > on your big box? If so, to what extent? Nah, just boot-testing tip/master before the merge window opens. Got a couple of boxes on which I throw tip/master on from time to time and see what breaks. I have caught a number of issues in past years, so it is a useful exercise. > Aside from habitually failing to trim emails, which of these was I > violating? ;-) That's my mail signature. In the hope that people see that doc and stop doing the same annoying things on LKML, it gets pasted in every mail of mine. I didn't mean you or your mail. :-) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette