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samples/bpf: switch trace_output sample to perf_buffer API

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