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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7BE28C4363A for ; Wed, 28 Oct 2020 21:51:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F15552245A for ; Wed, 28 Oct 2020 21:51:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="G21GnSZb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728197AbgJ1Vvl (ORCPT ); Wed, 28 Oct 2020 17:51:41 -0400 Received: from casper.infradead.org ([90.155.50.34]:44160 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728165AbgJ1Vvf (ORCPT ); Wed, 28 Oct 2020 17:51:35 -0400 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=2SDn0M9nv4bcedmTJRWAQlXu0K5RKkS42iU0N8vEXgU=; b=G21GnSZbpM6NCtTezkcR78B+0u RNexbqEXd49aKPg8kAXOypkrq4KHX8M4DSTyLuX2Vk4HWkAktL1UfXkKNR2lHKUii32dJXhcpw+sd akfj4+Apt+QhBDZUcc3jQyO+v7awHhq3Yh00EpmrfsVZa6fSzFn4xqGb9YjPPVwUBg37S3XIQNlxr IkpRR3a7z2AWJpg9Xw/pES8IJ0Kfr/S+ljQwAuklwtHYc/+JYzkIIKnaKKiIr6bUQthvafLGqCl8J n4yGdSnDsVfXW0FXhLZwzFS11g47itqs5lI/zjrPKze1rI6Hb/rh7UEwZ+NX4v5yUaqbr9QtLTUs/ UUtJPkgA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kXmqL-0005Y9-7E; Wed, 28 Oct 2020 14:54:30 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id AD2203006D0; Wed, 28 Oct 2020 15:54:28 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9FA942B064B32; Wed, 28 Oct 2020 15:54:28 +0100 (CET) Date: Wed, 28 Oct 2020 15:54:28 +0100 From: Peter Zijlstra To: mingo@kernel.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, paulmck@kernel.org, hch@lst.de, axboe@kernel.dk, chris@chris-wilson.co.uk, davem@davemloft.net, kuba@kernel.org, fweisbec@gmail.com, oleg@redhat.com, vincent.guittot@linaro.org Subject: Re: [RFC][PATCH v3 6/6] rcu/tree: Use irq_work_queue_remote() Message-ID: <20201028145428.GE2628@hirez.programming.kicks-ass.net> References: <20201028110707.971887448@infradead.org> <20201028111221.584884062@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201028111221.584884062@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2020 at 12:07:13PM +0100, Peter Zijlstra wrote: > AFAICT we only need/use irq_work_queue_on() on remote CPUs, since we > can directly access local state. So avoid the IRQ_WORK dependency and > use the unconditionally available irq_work_queue_remote(). > > This survives a number of TREE01 runs. OK, Paul mentioned on IRC that while it is extremely unlikely, this code does not indeed guarantee it will not try to IPI self. I'll try again.