Typically for percpu map element or data structure, once allocated,
most operations are lookup or in-place update. Deletion are really
rare. Currently, for percpu data strcture, 4 elements will be
refilled if the size is <= 256. Let us just do with one element
for percpu data. For example, for size 256 and 128 cpus, the
potential saving will be 3 * 256 * 128 * 128 = 12MB.
Acked-by: Hou Tao <houtao1@xxxxxxxxxx>
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
kernel/bpf/memalloc.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index 50ab2fecc005..f37998662146 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -485,11 +485,16 @@ static void init_refill_work(struct bpf_mem_cache *c)
static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
{
- /* To avoid consuming memory assume that 1st run of bpf
- * prog won't be doing more than 4 map_update_elem from
- * irq disabled region
+ int cnt = 1;
+
+ /* To avoid consuming memory, for non-percpu allocation, assume that
+ * 1st run of bpf prog won't be doing more than 4 map_update_elem from
+ * irq disabled region if unit size is less than or equal to 256.
+ * For all other cases, let us just do one allocation.
*/
- alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false);
+ if (!c->percpu_size && c->unit_size <= 256)
+ cnt = 4;
+ alloc_bulk(c, cnt, cpu_to_node(cpu), false);
}
static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
--
2.34.1
