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samples/bpf: switch trace_output sample to perf_buffer API 

Convert trace_output sample to libbpf's perf_buffer API.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2019-07-23 14:34:44 -07:00 committed by Alexei Starovoitov
parent f58a4d51d8
commit c17bec549c
1 changed files with 14 additions and 29 deletions
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43
samples/bpf/trace_output_user.c
View File

@ -18,9 +18,6 @@
#include <libbpf.h>
#include "bpf_load.h"
#include "perf-sys.h"
#include "trace_helpers.h"
static int pmu_fd;
static __u64 time_get_ns(void)
{
@ -31,12 +28,12 @@ static __u64 time_get_ns(void)
}
static __u64 start_time;
static __u64 cnt;
#define MAX_CNT 100000ll
static int print_bpf_output(void *data, int size)
static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
{
static __u64 cnt;
struct {
__u64 pid;
__u64 cookie;
@ -45,7 +42,7 @@ static int print_bpf_output(void *data, int size)
if (e->cookie != 0x12345678) {
printf("BUG pid %llx cookie %llx sized %d\n",
e->pid, e->cookie, size);
return LIBBPF_PERF_EVENT_ERROR;
return;
}
cnt++;
@ -53,30 +50,14 @@ static int print_bpf_output(void *data, int size)
if (cnt == MAX_CNT) {
printf("recv %lld events per sec\n",
MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
return LIBBPF_PERF_EVENT_DONE;
return;
}
return LIBBPF_PERF_EVENT_CONT;
}
static void test_bpf_perf_event(void)
{
struct perf_event_attr attr = {
.sample_type = PERF_SAMPLE_RAW,
.type = PERF_TYPE_SOFTWARE,
.config = PERF_COUNT_SW_BPF_OUTPUT,
};
int key = 0;
pmu_fd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
assert(pmu_fd >= 0);
assert(bpf_map_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
}
int main(int argc, char **argv)
{
struct perf_buffer_opts pb_opts = {};
struct perf_buffer *pb;
char filename[256];
FILE *f;
int ret;
@ -88,16 +69,20 @@ int main(int argc, char **argv)
return 1;
}
test_bpf_perf_event();
if (perf_event_mmap(pmu_fd) < 0)
pb_opts.sample_cb = print_bpf_output;
pb = perf_buffer__new(map_fd[0], 8, &pb_opts);
ret = libbpf_get_error(pb);
if (ret) {
printf("failed to setup perf_buffer: %d\n", ret);
return 1;
}
f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
(void) f;
start_time = time_get_ns();
ret = perf_event_poller(pmu_fd, print_bpf_output);
while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
}
kill(0, SIGINT);
return ret;
}