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Commit c17bec54 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

samples/bpf: switch trace_output sample to perf_buffer API 



Convert trace_output sample to libbpf's perf_buffer API.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent f58a4d51

samples/bpf/trace_output_user.c

+14 −29
Original line number Diff line number Diff line
@@ -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;

}