From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 May 2005 09:47:08 -0700 (PDT) From: Christoph Lameter Subject: Re: NUMA aware slab allocator V3 In-Reply-To: <1116251568.1005.29.camel@localhost> Message-ID: References: <20050512000444.641f44a9.akpm@osdl.org> <20050513000648.7d341710.akpm@osdl.org> <20050513043311.7961e694.akpm@osdl.org> <1116251568.1005.29.camel@localhost> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: Andrew Morton , linux-mm , Linux Kernel Mailing List , shai@scalex86.org, steiner@sgi.com List-ID: On Mon, 16 May 2005, Dave Hansen wrote: > There are some broken assumptions in the kernel that > CONFIG_DISCONTIG==CONFIG_NUMA. These usually manifest when code assumes > that one pg_data_t means one NUMA node. > > However, NUMA node ids are actually distinct from "discontigmem nodes". > A "discontigmem node" is just one physically contiguous area of memory, > thus one pg_data_t. Some (non-NUMA) Mac G5's have a gap in their > address space, so they get two discontigmem nodes. I thought the discontigous memory in one node was handled through zones? I.e. ZONE_HIGHMEM in i386? > So, that #error is bogus. It's perfectly valid to have multiple > discontigmem nodes, when the number of NUMA nodes is 1. MAX_NUMNODES > refers to discontigmem nodes, not NUMA nodes. Ok. We looked through the code and saw that the check may be removed without causing problems. However, there is still a feeling of uneasiness about this. To what node does numa_node_id() refer? And it is legit to use numa_node_id() to index cpu maps and stuff? How do the concepts of numa node id relate to discontig node ids? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org