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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham 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 05A8BC43142 for ; Tue, 26 Jun 2018 19:48:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F34426E0D for ; Tue, 26 Jun 2018 19:48:22 +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="TtbxufXJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F34426E0D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932205AbeFZTsU (ORCPT ); Tue, 26 Jun 2018 15:48:20 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:42142 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752109AbeFZTsT (ORCPT ); Tue, 26 Jun 2018 15:48:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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: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=e9Yzis0G53lJlIZsDwZNWfZ2kQOZic6NEoa4ZcabL18=; b=TtbxufXJlZelO9q4QrXHIoChS xcbMdBwkM8+TTIA75AcbEsyRxMYEblJCZ7doapwNMhezXHzumaxDmC+prgBoU8qVT67c1HyeYTwBg +iqZx2qo42znwHXZNlUFBZhbjtV4i+A92pZhsDQCJLgcLum0WTe+5p46YpkhGa9+o+NmIZiFQnD/i SBH3l51ai7M2yiA10V519JTG8g56kcFERNO3vsUIyxWSAx1QTfHWlrjxoJjk0FSZa2TxHWiXXLwev QUZ8uSIuQp6f/9+KmvKMKFGkA/NQeUlkMHx8nD+KBDgfbeHjY4OHgpKeYnu37JV+yjeiRHA3ivLL2 GxQ/XY4vQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fXtwf-0004wG-3s; Tue, 26 Jun 2018 19:48:09 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8EAFE2029FA0A; Tue, 26 Jun 2018 21:48:07 +0200 (CEST) Date: Tue, 26 Jun 2018 21:48:07 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org Subject: Re: [PATCH tip/core/rcu 13/22] rcu: Fix grace-period hangs due to race with CPU offline Message-ID: <20180626194807.GQ2494@hirez.programming.kicks-ass.net> References: <20180626002052.GA24146@linux.vnet.ibm.com> <20180626171048.2181-13-paulmck@linux.vnet.ibm.com> <20180626174424.GK2494@hirez.programming.kicks-ass.net> <20180626181937.GG3593@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180626181937.GG3593@linux.vnet.ibm.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 26, 2018 at 11:19:37AM -0700, Paul E. McKenney wrote: > The initial reason for ____cacheline_internodealigned_in_smp was that > some of the fields can be accessed by random CPUs, while others are > used more locally, give or take our usual contention over the handling > of CPU numbers. ;-) So that whole internode thing only matters for the insane VSMP case, where they take node to mean a cluster node, not a numa node. VSMP is a networked shared memory machine where, by necessity, the MESI protocol operates on page granularity. In general I tend to completely and utterly ignore that and let the VSMP people worry about things.