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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E1EFBC27C4F for ; Sat, 15 Jun 2024 08:59:37 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=PYbWvkuc; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4W1VT35N2Jz3cX7 for ; Sat, 15 Jun 2024 18:59:35 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=PYbWvkuc; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=infradead.org (client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=peterz@infradead.org; receiver=lists.ozlabs.org) Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4W1JrP3Tvhz3c4r for ; Sat, 15 Jun 2024 11:45:41 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Cmiivs9+4WenC6OP/1ZCnI/gkKg1dnHA0OIU4ZJ3byg=; b=PYbWvkucSg2aBQezLwmo+Qcd5e buXI3jXr9trafbVS5gAryDT/g51ZN2ZBHJAxUbhpaC2hB7zEs07wi7VegkBqFt449VYmSdHx7elSe WogNyhroF0DK54iaxAW50jWdlZDahTiZV5+Ls5WFRE8mrzX+a1Gce1UfgRgk+LFUxWnqraMHJ82U+ fjuNuq9GYv6VpVV9TPpSg4O/DlYpC/xa6zQU7QS5onXdbc6AjTRUO7+Q+u9isTmIEj0KMnjFgqrDf ebusEVDAofzzEFgSzUfwc/6aFrS74znvLxdtqTdMPASh9jObHTMaQX2D8eISlHn4iq1vMo6HzZ/MT vTtCcWSw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1sIITp-0000000HUbB-2pKJ; Sat, 15 Jun 2024 01:45:21 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 38AF1300886; Sat, 15 Jun 2024 03:45:21 +0200 (CEST) Date: Sat, 15 Jun 2024 03:45:21 +0200 From: Peter Zijlstra To: Vincent Guittot Subject: Re: [PATCH v2 00/14] Introducing TIF_NOTIFY_IPI flag Message-ID: <20240615014521.GR8774@noisy.programming.kicks-ass.net> References: <20240613181613.4329-1-kprateek.nayak@amd.com> <20240614092801.GL8774@noisy.programming.kicks-ass.net> <20240615012814.GP8774@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240615012814.GP8774@noisy.programming.kicks-ass.net> X-Mailman-Approved-At: Sat, 15 Jun 2024 18:57:30 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Rich Felker , Andreas Larsson , Dave Hansen , x86@kernel.org, "James E.J. Bottomley" , linux-openrisc@vger.kernel.org, Guo Ren , linux-csky@vger.kernel.org, David Vernet , "H. Peter Anvin" , Borislav Petkov , Thomas Gleixner , Kees Cook , Jonas Bonn , Valentin Schneider , Yoshinori Sato , linux-sh@vger.kernel.org, Helge Deller , "Rafael J. Wysocki" , Russell King , Christophe Leroy , Tony Battersby , Ingo Molnar , sparclinux@vger.kernel.org, Mel Gorman , "Naveen N. Rao" , Matt Turner , Benjamin Gray , Andrew Donnellan , "Paul E. McKenney" , Rik van Riel , Brian Gerst , Frederic Weisbecker , Xin Li , Richard Henderson , linuxppc-dev@lists.ozlabs.org, Nicholas Piggin , Stefan Kristiansson , Ivan Kokshaysky , Steven Rostedt , John Paul Adrian Glaubitz , Bjorn Helgaas , Stafford Horne , Dietmar Eggemann , linux-arm-kernel@lists.infradead.org, Ben Segall , Michal Simek , Daniel Lezcano , linux-parisc@vger.kernel.org, Tim Chen , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Julia Lawall , Dinh Nguyen , Leonardo Bras , "Gautham R. Shenoy" , linux-alpha@vger.kernel.org, Imran Khan , K Prateek Nayak , Rick Edgecombe , Daniel Bristot de Oliveira , "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sat, Jun 15, 2024 at 03:28:14AM +0200, Peter Zijlstra wrote: > On Fri, Jun 14, 2024 at 12:48:37PM +0200, Vincent Guittot wrote: > > The main problem is that need_resched becomes somewhat meaningless > > because it doesn't only mean "I need to resched a task" and we have > > to add more tests around even for those not using polling > > True, however we already had some of that by having the wakeup list, > that made nr_running less 'reliable'. Doesn't using !idle_cpu() instead of need_resched() in those balance paths already do the right thing? Checking need_resched() as an indicator of it getting work is already a bit an assumption. Also, Ingo, idle_cpu() and friends don't really belong in syscalls.c...