On 12/13/2023 6:30 AM, Yonghong Song wrote:
> 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.
>
> Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
> ---
> kernel/bpf/memalloc.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
> index 84987e97fd0a..a1d718ee264d 100644
> --- a/kernel/bpf/memalloc.c
> +++ b/kernel/bpf/memalloc.c
> @@ -483,11 +483,15 @@ static void init_refill_work(struct bpf_mem_cache *c)
>
> static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
> {
> + int cnt = 1;
> +
> /* 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
> */
Please update the comments accordingly.
> - 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)
