From 13808910713a98cc1159291e62cdfec92cc94d05 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 16 Oct 2007 01:25:27 -0700 Subject: Memoryless nodes: Generic management of nodemasks for various purposes Why do we need to support memoryless nodes? KAMEZAWA Hiroyuki wrote: > For fujitsu, problem is called "empty" node. > > When ACPI's SRAT table includes "possible nodes", ia64 bootstrap(acpi_numa_init) > creates nodes, which includes no memory, no cpu. > > I tried to remove empty-node in past, but that was denied. > It was because we can hot-add cpu to the empty node. > (node-hotplug triggered by cpu is not implemented now. and it will be ugly.) > > > For HP, (Lee can comment on this later), they have memory-less-node. > As far as I hear, HP's machine can have following configration. > > (example) > Node0: CPU0 memory AAA MB > Node1: CPU1 memory AAA MB > Node2: CPU2 memory AAA MB > Node3: CPU3 memory AAA MB > Node4: Memory XXX GB > > AAA is very small value (below 16MB) and will be omitted by ia64 bootstrap. > After boot, only Node 4 has valid memory (but have no cpu.) > > Maybe this is memory-interleave by firmware config. Christoph Lameter wrote: > Future SGI platforms (actually also current one can have but nothing like > that is deployed to my knowledge) have nodes with only cpus. Current SGI > platforms have nodes with just I/O that we so far cannot manage in the > core. So the arch code maps them to the nearest memory node. Lee Schermerhorn wrote: > For the HP platforms, we can configure each cell with from 0% to 100% > "cell local memory". When we configure with <100% CLM, the "missing > percentages" are interleaved by hardware on a cache-line granularity to > improve bandwidth at the expense of latency for numa-challenged > applications [and OSes, but not our problem ;-)]. When we boot Linux on > such a config, all of the real nodes have no memory--it all resides in a > single interleaved pseudo-node. > > When we boot Linux on a 100% CLM configuration [== NUMA], we still have > the interleaved pseudo-node. It contains a few hundred MB stolen from > the real nodes to contain the DMA zone. [Interleaved memory resides at > phys addr 0]. The memoryless-nodes patches, along with the zoneorder > patches, support this config as well. > > Also, when we boot a NUMA config with the "mem=" command line, > specifying less memory than actually exists, Linux takes the excluded > memory "off the top" rather than distributing it across the nodes. This > can result in memoryless nodes, as well. > This patch: Preparation for memoryless node patches. Provide a generic way to keep nodemasks describing various characteristics of NUMA nodes. Remove the node_online_map and the node_possible map and realize the same functionality using two nodes stats: N_POSSIBLE and N_ONLINE. [Lee.Schermerhorn@hp.com: Initialize N_*_MEMORY and N_CPU masks for non-NUMA config] Signed-off-by: Christoph Lameter Tested-by: Lee Schermerhorn Acked-by: Lee Schermerhorn Acked-by: Bob Picco Cc: Nishanth Aravamudan Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Signed-off-by: Lee Schermerhorn Cc: "Serge E. Hallyn" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 71013e6..0cc5b3e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -47,13 +47,21 @@ #include "internal.h" /* - * MCD - HACK: Find somewhere to initialize this EARLY, or make this - * initializer cleaner + * Array of node states. */ -nodemask_t node_online_map __read_mostly = { { [0] = 1UL } }; -EXPORT_SYMBOL(node_online_map); -nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL; -EXPORT_SYMBOL(node_possible_map); +nodemask_t node_states[NR_NODE_STATES] __read_mostly = { + [N_POSSIBLE] = NODE_MASK_ALL, + [N_ONLINE] = { { [0] = 1UL } }, +#ifndef CONFIG_NUMA + [N_NORMAL_MEMORY] = { { [0] = 1UL } }, +#ifdef CONFIG_HIGHMEM + [N_HIGH_MEMORY] = { { [0] = 1UL } }, +#endif + [N_CPU] = { { [0] = 1UL } }, +#endif /* NUMA */ +}; +EXPORT_SYMBOL(node_states); + unsigned long totalram_pages __read_mostly; unsigned long totalreserve_pages __read_mostly; long nr_swap_pages; -- cgit v1.1