bpf: Allow selecting numa node during map creation

The current map creation API does not allow to provide the numa-node
preference.  The memory usually comes from where the map-creation-process
is running.  The performance is not ideal if the bpf_prog is known to
always run in a numa node different from the map-creation-process.

One of the use case is sharding on CPU to different LRU maps (i.e.
an array of LRU maps).  Here is the test result of map_perf_test on
the INNER_LRU_HASH_PREALLOC test if we force the lru map used by
CPU0 to be allocated from a remote numa node:

[ The machine has 20 cores. CPU0-9 at node 0. CPU10-19 at node 1 ]

># taskset -c 10 ./map_perf_test 512 8 1260000 8000000
5:inner_lru_hash_map_perf pre-alloc 1628380 events per sec
4:inner_lru_hash_map_perf pre-alloc 1626396 events per sec
3:inner_lru_hash_map_perf pre-alloc 1626144 events per sec
6:inner_lru_hash_map_perf pre-alloc 1621657 events per sec
2:inner_lru_hash_map_perf pre-alloc 1621534 events per sec
1:inner_lru_hash_map_perf pre-alloc 1620292 events per sec
7:inner_lru_hash_map_perf pre-alloc 1613305 events per sec
0:inner_lru_hash_map_perf pre-alloc 1239150 events per sec  #<<<

After specifying numa node:
># taskset -c 10 ./map_perf_test 512 8 1260000 8000000
5:inner_lru_hash_map_perf pre-alloc 1629627 events per sec
3:inner_lru_hash_map_perf pre-alloc 1628057 events per sec
1:inner_lru_hash_map_perf pre-alloc 1623054 events per sec
6:inner_lru_hash_map_perf pre-alloc 1616033 events per sec
2:inner_lru_hash_map_perf pre-alloc 1614630 events per sec
4:inner_lru_hash_map_perf pre-alloc 1612651 events per sec
7:inner_lru_hash_map_perf pre-alloc 1609337 events per sec
0:inner_lru_hash_map_perf pre-alloc 1619340 events per sec #<<<

This patch adds one field, numa_node, to the bpf_attr.  Since numa node 0
is a valid node, a new flag BPF_F_NUMA_NODE is also added.  The numa_node
field is honored if and only if the BPF_F_NUMA_NODE flag is set.

Numa node selection is not supported for percpu map.

This patch does not change all the kmalloc.  F.e.
'htab = kzalloc()' is not changed since the object
is small enough to stay in the cache.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index d771a3872500..96e9c5c1dfc9 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -49,13 +49,15 @@ static int bpf_array_alloc_percpu(struct bpf_array *array)
 static struct bpf_map *array_map_alloc(union bpf_attr *attr)
 {
         bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
+        int numa_node = bpf_map_attr_numa_node(attr);
         struct bpf_array *array;
         u64 array_size;
         u32 elem_size;
 
         /* check sanity of attributes */
         if (attr->max_entries == 0 || attr->key_size != 4 ||
-            attr->value_size == 0 || attr->map_flags)
+            attr->value_size == 0 || attr->map_flags & ~BPF_F_NUMA_NODE ||
+            (percpu && numa_node != NUMA_NO_NODE))
                 return ERR_PTR(-EINVAL);
 
         if (attr->value_size > KMALLOC_MAX_SIZE)
@@ -77,7 +79,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
                 return ERR_PTR(-ENOMEM);
 
         /* allocate all map elements and zero-initialize them */
-        array = bpf_map_area_alloc(array_size);
+        array = bpf_map_area_alloc(array_size, numa_node);
         if (!array)
                 return ERR_PTR(-ENOMEM);
 
@@ -87,6 +89,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
         array->map.value_size = attr->value_size;
         array->map.max_entries = attr->max_entries;
         array->map.map_flags = attr->map_flags;
+        array->map.numa_node = numa_node;
         array->elem_size = elem_size;
 
         if (!percpu)