linux/samples/bpf/tracex2_user.c

96 lines
1.9 KiB
C
Raw Normal View History

samples/bpf: Add counting example for kfree_skb() function calls and the write() syscall this example has two probes in one C file that attach to different kprove events and use two different maps. 1st probe is x64 specific equivalent of dropmon. It attaches to kfree_skb, retrevies 'ip' address of kfree_skb() caller and counts number of packet drops at that 'ip' address. User space prints 'location - count' map every second. 2nd probe attaches to kprobe:sys_write and computes a histogram of different write sizes Usage: $ sudo tracex2 location 0xffffffff81695995 count 1 location 0xffffffff816d0da9 count 2 location 0xffffffff81695995 count 2 location 0xffffffff816d0da9 count 2 location 0xffffffff81695995 count 3 location 0xffffffff816d0da9 count 2 557145+0 records in 557145+0 records out 285258240 bytes (285 MB) copied, 1.02379 s, 279 MB/s syscall write() stats byte_size : count distribution 1 -> 1 : 3 | | 2 -> 3 : 0 | | 4 -> 7 : 0 | | 8 -> 15 : 0 | | 16 -> 31 : 2 | | 32 -> 63 : 3 | | 64 -> 127 : 1 | | 128 -> 255 : 1 | | 256 -> 511 : 0 | | 512 -> 1023 : 1118968 |************************************* | Ctrl-C at any time. Kernel will auto cleanup maps and programs $ addr2line -ape ./bld_x64/vmlinux 0xffffffff81695995 0xffffffff816d0da9 0xffffffff81695995: ./bld_x64/../net/ipv4/icmp.c:1038 0xffffffff816d0da9: ./bld_x64/../net/unix/af_unix.c:1231 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1427312966-8434-8-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 20:49:24 +01:00
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/bpf.h>
#include "libbpf.h"
#include "bpf_load.h"
#define MAX_INDEX 64
#define MAX_STARS 38
static void stars(char *str, long val, long max, int width)
{
int i;
for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
str[i] = '*';
if (val > max)
str[i - 1] = '+';
str[i] = '\0';
}
static void print_hist(int fd)
{
int key;
long value;
long data[MAX_INDEX] = {};
char starstr[MAX_STARS];
int i;
int max_ind = -1;
long max_value = 0;
for (key = 0; key < MAX_INDEX; key++) {
bpf_lookup_elem(fd, &key, &value);
data[key] = value;
if (value && key > max_ind)
max_ind = key;
if (value > max_value)
max_value = value;
}
printf(" syscall write() stats\n");
printf(" byte_size : count distribution\n");
for (i = 1; i <= max_ind + 1; i++) {
stars(starstr, data[i - 1], max_value, MAX_STARS);
printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
(1l << i) >> 1, (1l << i) - 1, data[i - 1],
MAX_STARS, starstr);
}
}
static void int_exit(int sig)
{
print_hist(map_fd[1]);
exit(0);
}
int main(int ac, char **argv)
{
char filename[256];
long key, next_key, value;
FILE *f;
int i;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
signal(SIGINT, int_exit);
/* start 'ping' in the background to have some kfree_skb events */
f = popen("ping -c5 localhost", "r");
(void) f;
/* start 'dd' in the background to have plenty of 'write' syscalls */
f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
(void) f;
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
for (i = 0; i < 5; i++) {
key = 0;
while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {
bpf_lookup_elem(map_fd[0], &next_key, &value);
printf("location 0x%lx count %ld\n", next_key, value);
key = next_key;
}
if (key)
printf("\n");
sleep(1);
}
print_hist(map_fd[1]);
return 0;
}