[RFC Patch V1 29/30] mm, x86: Enable memoryless node support to better support CPU/memory hotplug
From: Jiang Liu
Date: Fri Jul 11 2014 - 03:38:34 EST
With current implementation, all CPUs within a NUMA node will be
assocaited with another NUMA node if the node has no memory installed.
For example, on a four-node system, CPUs on node 2 and 3 are associated
with node 0 when are no memory install on node 2 and 3, which may
confuse users.
root@bkd01sdp:~# numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119
node 0 size: 15602 MB
node 0 free: 15014 MB
node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
node 1 size: 15985 MB
node 1 free: 15686 MB
node distances:
node 0 1
0: 10 21
1: 21 10
To be worse, the CPU affinity relationship won't get fixed even after
memory has been added to those nodes. After memory hot-addition to
node 2, CPUs on node 2 are still associated with node 0. This may cause
sub-optimal performance.
root@bkd01sdp:/sys/devices/system/node/node2# numactl --hardware
available: 3 nodes (0-2)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119
node 0 size: 15602 MB
node 0 free: 14743 MB
node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
node 1 size: 15985 MB
node 1 free: 15715 MB
node 2 cpus:
node 2 size: 128 MB
node 2 free: 128 MB
node distances:
node 0 1 2
0: 10 21 21
1: 21 10 21
2: 21 21 10
With support of memoryless node enabled, it will correctly report system
hardware topology for nodes without memory installed.
root@bkd01sdp:~# numactl --hardware
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74
node 0 size: 15725 MB
node 0 free: 15129 MB
node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
node 1 size: 15862 MB
node 1 free: 15627 MB
node 2 cpus: 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104
node 2 size: 0 MB
node 2 free: 0 MB
node 3 cpus: 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119
node 3 size: 0 MB
node 3 free: 0 MB
node distances:
node 0 1 2 3
0: 10 21 21 21
1: 21 10 21 21
2: 21 21 10 21
3: 21 21 21 10
With memoryless node enabled, CPUs are correctly associated with node 2
after memory hot-addition to node 2.
root@bkd01sdp:/sys/devices/system/node/node2# numactl --hardware
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74
node 0 size: 15725 MB
node 0 free: 14872 MB
node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
node 1 size: 15862 MB
node 1 free: 15641 MB
node 2 cpus: 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104
node 2 size: 128 MB
node 2 free: 127 MB
node 3 cpus: 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119
node 3 size: 0 MB
node 3 free: 0 MB
node distances:
node 0 1 2 3
0: 10 21 21 21
1: 21 10 21 21
2: 21 21 10 21
3: 21 21 21 10
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 3 +++
arch/x86/kernel/acpi/boot.c | 5 ++++-
arch/x86/kernel/smpboot.c | 2 ++
arch/x86/mm/numa.c | 42 +++++++++++++++++++++++++++++++++++-------
4 files changed, 44 insertions(+), 8 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8f749ef0fdc..f35b25b88625 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1887,6 +1887,9 @@ config USE_PERCPU_NUMA_NODE_ID
def_bool y
depends on NUMA
+config HAVE_MEMORYLESS_NODES
+ def_bool NUMA
+
config ARCH_ENABLE_SPLIT_PMD_PTLOCK
def_bool y
depends on X86_64 || X86_PAE
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 86281ffb96d6..3b5641703a49 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -612,6 +612,8 @@ static void acpi_map_cpu2node(acpi_handle handle, int cpu, int physid)
if (nid != -1) {
set_apicid_to_node(physid, nid);
numa_set_node(cpu, nid);
+ if (node_online(nid))
+ set_cpu_numa_mem(cpu, local_memory_node(nid));
}
#endif
}
@@ -644,9 +646,10 @@ int acpi_unmap_lsapic(int cpu)
{
#ifdef CONFIG_ACPI_NUMA
set_apicid_to_node(per_cpu(x86_cpu_to_apicid, cpu), NUMA_NO_NODE);
+ set_cpu_numa_mem(cpu, NUMA_NO_NODE);
#endif
- per_cpu(x86_cpu_to_apicid, cpu) = -1;
+ per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
set_cpu_present(cpu, false);
num_processors--;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 5492798930ef..4a5437989ffe 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -162,6 +162,8 @@ static void smp_callin(void)
__func__, cpuid);
}
+ set_numa_mem(local_memory_node(cpu_to_node(cpuid)));
+
/*
* the boot CPU has finished the init stage and is spinning
* on callin_map until we finish. We are free to set up this
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index eec4f6c322bb..0d17c05480d2 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -22,6 +22,7 @@
int __initdata numa_off;
nodemask_t numa_nodes_parsed __initdata;
+static nodemask_t numa_nodes_empty __initdata;
struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
EXPORT_SYMBOL(node_data);
@@ -523,8 +524,12 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
end = max(mi->blk[i].end, end);
}
- if (start < end)
+ if (start < end) {
setup_node_data(nid, start, end);
+ } else if (IS_ENABLED(CONFIG_HAVE_MEMORYLESS_NODES)) {
+ setup_node_data(nid, 0, 0);
+ node_set(nid, numa_nodes_empty);
+ }
}
/* Dump memblock with node info and return. */
@@ -541,14 +546,18 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
*/
static void __init numa_init_array(void)
{
- int rr, i;
+ int i, rr = MAX_NUMNODES;
- rr = first_node(node_online_map);
for (i = 0; i < nr_cpu_ids; i++) {
+ /* Search for an onlined node with memory */
+ do {
+ if (rr != MAX_NUMNODES)
+ rr = next_node(rr, node_online_map);
+ if (rr == MAX_NUMNODES)
+ rr = first_node(node_online_map);
+ } while (!node_spanned_pages(rr));
+
numa_set_node(i, rr);
- rr = next_node(rr, node_online_map);
- if (rr == MAX_NUMNODES)
- rr = first_node(node_online_map);
}
}
@@ -694,9 +703,12 @@ static __init int find_near_online_node(int node)
{
int n, val;
int min_val = INT_MAX;
- int best_node = -1;
+ int best_node = NUMA_NO_NODE;
for_each_online_node(n) {
+ if (!node_spanned_pages(n))
+ continue;
+
val = node_distance(node, n);
if (val < min_val) {
@@ -737,6 +749,22 @@ void __init init_cpu_to_node(void)
if (!node_online(node))
node = find_near_online_node(node);
numa_set_node(cpu, node);
+ if (node_spanned_pages(node))
+ set_cpu_numa_mem(cpu, node);
+ if (IS_ENABLED(CONFIG_HAVE_MEMORYLESS_NODES))
+ node_clear(node, numa_nodes_empty);
+ }
+
+ /* Destroy empty nodes */
+ if (IS_ENABLED(CONFIG_HAVE_MEMORYLESS_NODES)) {
+ int nid;
+ const size_t nd_size = roundup(sizeof(pg_data_t), PAGE_SIZE);
+
+ for_each_node_mask(nid, numa_nodes_empty) {
+ node_set_offline(nid);
+ memblock_free(__pa(node_data[nid]), nd_size);
+ node_data[nid] = NULL;
+ }
}
}
--
1.7.10.4
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