From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jack Steiner Date: Thu, 10 Nov 2005 02:54:21 +0000 Subject: Re: [RFC] 4-level page table directories. Message-Id: <20051110025421.GA3765@sgi.com> List-Id: References: <20051027041709.GA13193@attica.americas.sgi.com> In-Reply-To: <20051027041709.GA13193@attica.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Wed, Nov 09, 2005 at 04:27:48PM -0800, Luck, Tony wrote: > >Is it possible you are mixing up MAX_NUMALINK_NODES (the maximum > >system size, i.e., the maximum number of nodes in a numalink domain) > >with CONFIG_NR_CPUS (the maximum SSI size)? > > > >I'm pretty confident SGI has not proposed setting CONFIG_NR_CPUS384 > >to any OSV. ;-) > > It's always possible that I'm confused. Here's the message where > Robin introduced the rationale for 4-level page tables: You are not confused, but this is a confusing area. A lot of the terminology that we use to describe these configurations has been misused or poorly defined. Altix currently supports a max SSI of 256 nodes (1024p). However, multiple SSIs can be interconnected via NUMALINK. XPMEM provides the ability for a single task running within an SSI to access ALL the memory thruout the NUMALINK fabric, ie. memory can be exported from a task running within one SSI to a task running in another SSI. For example, if you have: 128 GB per SSI 16 SSIs connected via NUMALINK a task running within an SSI can access all 2TB of memory (excluding memory used by the kernel) Note: SSI = fat node = cluster > > http://tinyurl.com/bewsk > > In that he says "current = 2048" ... which I think is how many > cpus can be in the whole box ... 512 is the current max cpus in > a coherence domain (and thus the max that a single instance of > Linux will see today). > > With Montecito (dual core, two threads in each core) the number > of cpus Linux sees will be quadrupled in a system with the same > number of sockets. Add more sockets, and the 16384 number may > not be impossible. > > -Tony -- Thanks Jack Steiner (steiner@sgi.com) 651-683-5302 Principal Engineer SGI - Silicon Graphics, Inc.