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authorJakub Kicinski <jakub.kicinski@netronome.com>2018-05-10 10:24:37 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-05-11 01:40:51 +0200
commite3687510fce2a5b039133be8979b2c8e8cbffa67 (patch)
tree2bccacf26947c659d816faafcc6eeaabf980cbca /tools/bpf
parentcb9c28ef579debbc51e48b37f2534390f5da8467 (diff)
tools: bpftool: use PERF_SAMPLE_TIME instead of reading the clock
Ask the kernel to include sample time in each even instead of reading the clock. This is also more accurate because our clock reading was done when user space would dump the buffer, not when sample was produced. Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools/bpf')
-rw-r--r--tools/bpf/bpftool/map_perf_ring.c17
1 files changed, 6 insertions, 11 deletions
diff --git a/tools/bpf/bpftool/map_perf_ring.c b/tools/bpf/bpftool/map_perf_ring.c
index c5a2ced8552d..9ae4bb8a2cad 100644
--- a/tools/bpf/bpftool/map_perf_ring.c
+++ b/tools/bpf/bpftool/map_perf_ring.c
@@ -39,6 +39,7 @@ struct event_ring_info {
struct perf_event_sample {
struct perf_event_header header;
+ u64 time;
__u32 size;
unsigned char data[];
};
@@ -57,17 +58,9 @@ print_bpf_output(struct event_ring_info *ring, struct perf_event_sample *e)
__u64 id;
__u64 lost;
} *lost = (void *)e;
- struct timespec ts;
-
- if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
- perror("Can't read clock for timestamp");
- return;
- }
if (json_output) {
jsonw_start_object(json_wtr);
- jsonw_name(json_wtr, "timestamp");
- jsonw_uint(json_wtr, ts.tv_sec * 1000000000ull + ts.tv_nsec);
jsonw_name(json_wtr, "type");
jsonw_uint(json_wtr, e->header.type);
jsonw_name(json_wtr, "cpu");
@@ -75,6 +68,8 @@ print_bpf_output(struct event_ring_info *ring, struct perf_event_sample *e)
jsonw_name(json_wtr, "index");
jsonw_uint(json_wtr, ring->key);
if (e->header.type == PERF_RECORD_SAMPLE) {
+ jsonw_name(json_wtr, "timestamp");
+ jsonw_uint(json_wtr, e->time);
jsonw_name(json_wtr, "data");
print_data_json(e->data, e->size);
} else if (e->header.type == PERF_RECORD_LOST) {
@@ -89,8 +84,8 @@ print_bpf_output(struct event_ring_info *ring, struct perf_event_sample *e)
jsonw_end_object(json_wtr);
} else {
if (e->header.type == PERF_RECORD_SAMPLE) {
- printf("== @%ld.%ld CPU: %d index: %d =====\n",
- (long)ts.tv_sec, ts.tv_nsec,
+ printf("== @%lld.%09lld CPU: %d index: %d =====\n",
+ e->time / 1000000000ULL, e->time % 1000000000ULL,
ring->cpu, ring->key);
fprint_hex(stdout, e->data, e->size, " ");
printf("\n");
@@ -185,7 +180,7 @@ static void perf_event_unmap(void *mem)
static int bpf_perf_event_open(int map_fd, int key, int cpu)
{
struct perf_event_attr attr = {
- .sample_type = PERF_SAMPLE_RAW,
+ .sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_TIME,
.type = PERF_TYPE_SOFTWARE,
.config = PERF_COUNT_SW_BPF_OUTPUT,
};