From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Busch Subject: Re: [PATCH 1/7] node: Link memory nodes to their compute nodes Date: Thu, 15 Nov 2018 07:59:20 -0700 Message-ID: <20181115145920.GG11416@localhost.localdomain> References: <20181114224921.12123-2-keith.busch@intel.com> <20181115135710.GD19286@bombadil.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181115135710.GD19286@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , Rafael Wysocki , Dave Hansen , Dan Williams List-Id: linux-acpi@vger.kernel.org On Thu, Nov 15, 2018 at 05:57:10AM -0800, Matthew Wilcox wrote: > On Wed, Nov 14, 2018 at 03:49:14PM -0700, Keith Busch wrote: > > Memory-only nodes will often have affinity to a compute node, and > > platforms have ways to express that locality relationship. > > > > A node containing CPUs or other DMA devices that can initiate memory > > access are referred to as "memory iniators". A "memory target" is a > > node that provides at least one phyiscal address range accessible to a > > memory initiator. > > I think I may be confused here. If there is _no_ link from node X to > node Y, does that mean that node X's CPUs cannot access the memory on > node Y? In my mind, all nodes can access all memory in the system, > just not with uniform bandwidth/latency. The link is just about which nodes are "local". It's like how nodes have a cpulist. Other CPUs not in the node's list can acces that node's memory, but the ones in the mask are local, and provide useful optimization hints. Would a node mask would be prefered to symlinks?