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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 66992C2D0DB for ; Sat, 25 Jan 2020 11:20:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 300BF2070A for ; Sat, 25 Jan 2020 11:20:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ptV38WIP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726565AbgAYLUJ (ORCPT ); Sat, 25 Jan 2020 06:20:09 -0500 Received: from merlin.infradead.org ([205.233.59.134]:50382 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbgAYLUJ (ORCPT ); Sat, 25 Jan 2020 06:20:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=OP0jUwmmVf5k5VHaoyszroM7/NftdfADwRXKDwwLdIk=; b=ptV38WIPx+l6Yf6WtjGHgCfGFe AgMWOXh+dtKIvzf9sJr2QFX8KIPn567Cren4byAkUNCrELh2bnIGEhnjrzg4/VSpoBhaqJpz0wJdW v3WCYrq8Cj34EhWxdi0ImmM+Fxd5B5HQa9YqOZtpfsEwsMO0DtrC2ZmGNSZSEab7GSNSclh4zPLRt Mq/0W4rMTgG2ErY6PRFSi97BOwYqRryRjFWkt/r3EHJfqfHW/tRHlXM4uHxdB9NB+YDM/K1A5jThf 3GZY6UrKeKkFaEVrSzVzYPsqKPd0dKhxiReYfqGxATtZYQXzMJJwE86yhsNd/oWDiEhTTKjOX4PFU Wmw+TCmA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ivJTS-0004yl-Ip; Sat, 25 Jan 2020 11:19:34 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id C885F980BB0; Sat, 25 Jan 2020 12:19:31 +0100 (CET) Date: Sat, 25 Jan 2020 12:19:31 +0100 From: Peter Zijlstra To: Alex Kogan Cc: Waiman Long , linux@armlinux.org.uk, Ingo Molnar , Will Deacon , Arnd Bergmann , linux-arch@vger.kernel.org, linux-arm-kernel , linux-kernel@vger.kernel.org, Thomas Gleixner , Borislav Petkov , hpa@zytor.com, x86@kernel.org, Hanjun Guo , Jan Glauber , Steven Sistare , Daniel Jordan , dave.dice@oracle.com Subject: Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Message-ID: <20200125111931.GW11457@worktop.programming.kicks-ass.net> References: <20191230194042.67789-5-alex.kogan@oracle.com> <20200121132949.GL14914@hirez.programming.kicks-ass.net> <3862F8A1-FF9B-40AD-A88E-2C0BA7AF6F58@oracle.com> <20200124075235.GX14914@hirez.programming.kicks-ass.net> <2c6741c5-d89d-4b2c-cebe-a7c7f6eed884@redhat.com> <48ce49e5-98a7-23cd-09f4-8290a65abbb5@redhat.com> <8D3AFB47-B595-418C-9568-08780DDC58FF@oracle.com> <714892cd-d96f-4d41-ae8b-d7b7642a6e3c@redhat.com> <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> 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 Fri, Jan 24, 2020 at 01:19:05PM -0500, Alex Kogan wrote: > Is there a lightweight way to identify such a “prioritized” thread? No; people might for instance care about tail latencies between their identically spec'ed worker tasks. In general it turns out that priority is a dynamic concept, not a static one.