[PATCH bpf-next v2 1/2] samples: bpf: improve xdp1 example

[Matteo Croce]

Store only the total packet count for every protocol, instead of the
whole per-cpu array.
Use bpf_map_get_next_key() to iterate the map, instead of looking up
all the protocols.

Signed-off-by: Matteo Croce <mcr...@redhat.com>
---
 samples/bpf/xdp1_user.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c
index b02c531510ed..4f3d824fc044 100644
--- a/samples/bpf/xdp1_user.c
+++ b/samples/bpf/xdp1_user.c
@@ -34,26 +34,24 @@ static void int_exit(int sig)
 static void poll_stats(int map_fd, int interval)
 {
        unsigned int nr_cpus = bpf_num_possible_cpus();
-       const unsigned int nr_keys = 256;
-       __u64 values[nr_cpus], prev[nr_keys][nr_cpus];
-       __u32 key;
+       __u64 values[nr_cpus], prev[UINT8_MAX] = { 0 };
        int i;
 
-       memset(prev, 0, sizeof(prev));
-
        while (1) {
+               __u32 key = UINT32_MAX;
+
                sleep(interval);
 
-               for (key = 0; key < nr_keys; key++) {
+               while (bpf_map_get_next_key(map_fd, &key, &key) != -1) {
                        __u64 sum = 0;
 
                        assert(bpf_map_lookup_elem(map_fd, &key, values) == 0);
                        for (i = 0; i < nr_cpus; i++)
-                               sum += (values[i] - prev[key][i]);
-                       if (sum)
+                               sum += values[i];
+                       if (sum > prev[key])
                                printf("proto %u: %10llu pkt/s\n",
-                                      key, sum / interval);
-                       memcpy(prev[key], values, sizeof(values));
+                                      key, (sum - prev[key]) / interval);
+                       prev[key] = sum;
                }
        }
 }
-- 
2.19.1