From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jakub Kicinski Subject: [PATCH bpf-next 1/7] tools: bpftool: use PERF_SAMPLE_TIME instead of reading the clock Date: Thu, 10 May 2018 10:24:37 -0700 Message-ID: <20180510172443.17238-2-jakub.kicinski@netronome.com> References: <20180510172443.17238-1-jakub.kicinski@netronome.com> Cc: oss-drivers@netronome.com, netdev@vger.kernel.org, Jakub Kicinski To: alexei.starovoitov@gmail.com, daniel@iogearbox.net Return-path: Received: from mail-qt0-f196.google.com ([209.85.216.196]:39208 "EHLO mail-qt0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965017AbeEJRY6 (ORCPT ); Thu, 10 May 2018 13:24:58 -0400 Received: by mail-qt0-f196.google.com with SMTP id f1-v6so3559386qtj.6 for ; Thu, 10 May 2018 10:24:58 -0700 (PDT) In-Reply-To: <20180510172443.17238-1-jakub.kicinski@netronome.com> Sender: netdev-owner@vger.kernel.org List-ID: 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 Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet --- tools/bpf/bpftool/map_perf_ring.c | 17 ++++++----------- 1 file 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, }; -- 2.17.0