The current numa emulation capabilities for splitting System RAM by a
fixed size or by a set number of nodes may result in some nodes being
larger than others. The implementation prioritizes establishing a
minimum usable memory size over satisfying the requested number of numa
nodes.
Introduce a uniform split capability that evenly partitions each
physical numa node into N emulated nodes. For example numa=fake=3U
creates 6 emulated nodes total on a system that has 2 physical nodes.
This capability is useful for debugging and evaluating platform
memory-side-cache capabilities as described by the ACPI HMAT (see
5.2.27.5 Memory Side Cache Information Structure in ACPI 6.2a)
Compare numa=fake=6 that results in only 5 nodes being created against
numa=fake=3U which takes the 2 physical nodes and evenly divides them.
numa=fake=6
available: 5 nodes (0-4)
node 0 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
node 0 size: 2648 MB
node 0 free: 2443 MB
node 1 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 1 size: 2672 MB
node 1 free: 2442 MB
node 2 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
node 2 size: 5291 MB
node 2 free: 5278 MB
node 3 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 3 size: 2677 MB
node 3 free: 2665 MB
node 4 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 4 size: 2676 MB
node 4 free: 2663 MB
node distances:
node 0 1 2 3 4
0: 10 20 10 20 20
1: 20 10 20 10 10
2: 10 20 10 20 20
3: 20 10 20 10 10
4: 20 10 20 10 10
numa=fake=3U
# numactl --hardware
available: 6 nodes (0-5)
node 0 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
node 0 size: 2900 MB
node 0 free: 2637 MB
node 1 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
node 1 size: 3023 MB
node 1 free: 3012 MB
node 2 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
node 2 size: 2015 MB
node 2 free: 2004 MB
node 3 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 3 size: 2704 MB
node 3 free: 2522 MB
node 4 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 4 size: 2709 MB
node 4 free: 2698 MB
node 5 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
node 5 size: 2612 MB
node 5 free: 2601 MB
node distances:
node 0 1 2 3 4 5
0: 10 10 10 20 20 20
1: 10 10 10 20 20 20
2: 10 10 10 20 20 20
3: 20 20 20 10 10 10
4: 20 20 20 10 10 10
5: 20 20 20 10 10 10
Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <x86@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Documentation/x86/x86_64/boot-options.txt | 4 +
arch/x86/mm/numa_emulation.c | 96 +++++++++++++++++++++++------
2 files changed, 81 insertions(+), 19 deletions(-)
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index b297c48389b9..d1332609a17e 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -156,6 +156,10 @@ NUMA
If given as an integer, fills all system RAM with N fake nodes
interleaved over physical nodes.
+ numa=fake=<N>U
+ If given as an integer followed by 'U', it will divide each
+ physical node into N emulated nodes.
+
ACPI
acpi=off Don't enable ACPI
diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 22cbad56acab..039db00541b7 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -204,34 +204,58 @@ static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
*
* Returns zero on success or negative on error.
*/
-static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
+static int __init split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
struct numa_meminfo *pi,
- u64 addr, u64 max_addr, u64 size)
+ u64 addr, u64 max_addr, u64 size,
+ int nr_nodes, struct numa_memblk *pblk,
+ int nid)
{
nodemask_t physnode_mask = numa_nodes_parsed;
+ int i, ret, uniform = 0;
u64 min_size;
- int nid = 0;
- int i, ret;
- if (!size)
+ if ((!size && !nr_nodes) || (nr_nodes && !pblk))
return -1;
+
/*
- * The limit on emulated nodes is MAX_NUMNODES, so the size per node is
- * increased accordingly if the requested size is too small. This
- * creates a uniform distribution of node sizes across the entire
- * machine (but not necessarily over physical nodes).
+ * In the 'uniform' case split the passed in physical node by
+ * nr_nodes, in the non-uniform case, ignore the passed in
+ * physical block and try to create nodes of at least size
+ * @size.
+ *
+ * In the uniform case, split the nodes strictly by physical
+ * capacity, i.e. ignore holes. In the non-uniform case account
+ * for holes and treat @size as a minimum floor.
*/
- min_size = (max_addr - addr - mem_hole_size(addr, max_addr)) / MAX_NUMNODES;
- min_size = max(min_size, FAKE_NODE_MIN_SIZE);
- if ((min_size & FAKE_NODE_MIN_HASH_MASK) < min_size)
- min_size = (min_size + FAKE_NODE_MIN_SIZE) &
- FAKE_NODE_MIN_HASH_MASK;
+ if (!nr_nodes)
+ nr_nodes = MAX_NUMNODES;
+ else {
+ nodes_clear(physnode_mask);
+ node_set(pblk->nid, physnode_mask);
+ uniform = 1;
+ }
+
+ if (uniform) {
+ min_size = (max_addr - addr) / nr_nodes;
+ size = min_size;
+ } else {
+ /*
+ * The limit on emulated nodes is MAX_NUMNODES, so the
+ * size per node is increased accordingly if the
+ * requested size is too small. This creates a uniform
+ * distribution of node sizes across the entire machine
+ * (but not necessarily over physical nodes).
+ */
+ min_size = (max_addr - addr - mem_hole_size(addr, max_addr))
+ / nr_nodes;
+ }
+ min_size = ALIGN(max(min_size, FAKE_NODE_MIN_SIZE), FAKE_NODE_MIN_SIZE);
if (size < min_size) {
pr_err("Fake node size %LuMB too small, increasing to %LuMB\n",
size >> 20, min_size >> 20);
size = min_size;
}
- size &= FAKE_NODE_MIN_HASH_MASK;
+ size = ALIGN_DOWN(size, FAKE_NODE_MIN_SIZE);
/*
* Fill physical nodes with fake nodes of size until there is no memory
@@ -248,10 +272,14 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
node_clear(i, physnode_mask);
continue;
}
+
start = pi->blk[phys_blk].start;
limit = pi->blk[phys_blk].end;
- end = find_end_of_node(start, limit, size);
+ if (uniform)
+ end = start + size;
+ else
+ end = find_end_of_node(start, limit, size);
/*
* If there won't be at least FAKE_NODE_MIN_SIZE of
* non-reserved memory in ZONE_DMA32 for the next node,
@@ -266,7 +294,8 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
* next node, this one must extend to the end of the
* physical node.
*/
- if (limit - end - mem_hole_size(end, limit) < size)
+ if ((limit - end - mem_hole_size(end, limit) < size)
+ && !uniform)
end = limit;
ret = emu_setup_memblk(ei, pi, nid++ % MAX_NUMNODES,
@@ -276,7 +305,15 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
return ret;
}
}
- return 0;
+ return nid;
+}
+
+static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
+ struct numa_meminfo *pi,
+ u64 addr, u64 max_addr, u64 size)
+{
+ return split_nodes_size_interleave_uniform(ei, pi, addr, max_addr, size,
+ 0, NULL, NUMA_NO_NODE);
}
int __init setup_emu2phys_nid(int *dfl_phys_nid)
@@ -346,7 +383,28 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
* the fixed node size. Otherwise, if it is just a single number N,
* split the system RAM into N fake nodes.
*/
- if (strchr(emu_cmdline, 'M') || strchr(emu_cmdline, 'G')) {
+ if (strchr(emu_cmdline, 'U')) {
+ nodemask_t physnode_mask = numa_nodes_parsed;
+ unsigned long n;
+ int nid = 0;
+
+ n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
+ ret = -1;
+ for_each_node_mask(i, physnode_mask) {
+ ret = split_nodes_size_interleave_uniform(&ei, &pi,
+ pi.blk[i].start, pi.blk[i].end, 0,
+ n, &pi.blk[i], nid);
+ if (ret < 0)
+ break;
+ if (ret < n) {
+ pr_info("%s: phys: %d only got %d of %ld nodes, failing\n",
+ __func__, i, ret, n);
+ ret = -1;
+ break;
+ }
+ nid = ret;
+ }
+ } else if (strchr(emu_cmdline, 'M') || strchr(emu_cmdline, 'G')) {
u64 size;
size = memparse(emu_cmdline, &emu_cmdline);
