Re: [PATCH] samples/bpf: Update sockex2: get the expected output results

guodongtai
2023-07-27T03:33:09Z

On Wed, 26 Jul 2023 23:22:49 +0200
Nicolas Schier <nicolas@fjasle.eu> wrote:

> On Wed, Jul 26, 2023 at 03:09:55PM +0800 George Guo wrote:
> > Running "ping -4 -c5 localhost" only shows 4 times prints not 5:
> >
> > $ sudo ./samples/bpf/sockex2
> > ip 127.0.0.1 bytes 392 packets 4
> > ip 127.0.0.1 bytes 784 packets 8
> > ip 127.0.0.1 bytes 1176 packets 12
> > ip 127.0.0.1 bytes 1568 packets 16
> >
> > debug it with num prints:
> > $ sudo ./samples/bpf/sockex2
> > num = 1: ip 127.0.0.1 bytes 392 packets 4
> > num = 2: ip 127.0.0.1 bytes 784 packets 8
> > num = 3: ip 127.0.0.1 bytes 1176 packets 12
> > num = 4: ip 127.0.0.1 bytes 1568 packets 16
> >
> > The reason is that we check it faster, just put sleep(1) before
> > check while(bpf_map_get_next_key(map_fd, &key, &next_key) == 0).
> > Now we get the expected results:
> >
> > $ sudo ./samples/bpf/sockex2
> > num = 0: ip 127.0.0.1 bytes 392 packets 4
> > num = 1: ip 127.0.0.1 bytes 784 packets 8
> > num = 2: ip 127.0.0.1 bytes 1176 packets 12
> > num = 3: ip 127.0.0.1 bytes 1568 packets 16
> > num = 4: ip 127.0.0.1 bytes 1960 packets 20
> >
> > Signed-off-by: George Guo <guodongtai@kylinos.cn>
> > ---
>
> Thanks, sounds reasonable to me (but I haven't checked it). Might
> you want to minimize the diff to only contain the move of the sleep
> call?
>
> Kind regards,
> Nicolas
>
>
> > samples/bpf/sockex2_user.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/samples/bpf/sockex2_user.c b/samples/bpf/sockex2_user.c
> > index 2c18471336f0..84bf1ab77649 100644
> > --- a/samples/bpf/sockex2_user.c
> > +++ b/samples/bpf/sockex2_user.c
> > @@ -18,8 +18,8 @@ int main(int ac, char **argv)
> > struct bpf_program *prog;
> > struct bpf_object *obj;
> > int map_fd, prog_fd;
> > - char filename[256];
> > - int i, sock, err;
> > + char filename[256], command[64];
> > + int i, sock, err, num = 5;
> > FILE *f;
> >
> > snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
> > @@ -42,21 +42,22 @@ int main(int ac, char **argv)
> > assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF,
> > &prog_fd, sizeof(prog_fd)) == 0);
> >
> > - f = popen("ping -4 -c5 localhost", "r");
> > + snprintf(command, sizeof(command), "ping -4 -c%d
> > localhost", num);
> > + f = popen(command, "r");
> > (void) f;
> >
> > - for (i = 0; i < 5; i++) {
> > + for (i = 0; i < num; i++) {
> > int key = 0, next_key;
> > struct pair value;
> >
> > + sleep(1);
> > while (bpf_map_get_next_key(map_fd, &key,
> > &next_key) == 0) { bpf_map_lookup_elem(map_fd, &next_key, &value);
> > - printf("ip %s bytes %lld packets %lld\n",
> > + printf("num = %d: ip %s bytes %lld packets
> > %lld\n", i, inet_ntoa((struct in_addr){htonl(next_key)}),
> > value.bytes, value.packets);
> > key = next_key;
> > }
> > - sleep(1);
> > }
> > return 0;
> > }
> > --
> > 2.34.1
>

hi，

the diff to only contain the move of the sleep call likes this:

diff --git a/samples/bpf/sockex2_user.c b/samples/bpf/sockex2_user.c
index 2c18471336f0..82bb38b9cab0 100644
--- a/samples/bpf/sockex2_user.c
+++ b/samples/bpf/sockex2_user.c
@@ -49,6 +49,7 @@ int main(int ac, char **argv)
int key = 0, next_key;
struct pair value;

+ sleep(1);
while (bpf_map_get_next_key(map_fd, &key, &next_key) ==
0) { bpf_map_lookup_elem(map_fd, &next_key, &value);
printf("ip %s bytes %lld packets %lld\n",
@@ -56,7 +57,6 @@ int main(int ac, char **argv)
value.bytes, value.packets);
key = next_key;
}
- sleep(1);
}
return 0;
}