From: Arnaldo Carvalho de Melo <a...@redhat.com> This was causing bogus values to be shown at the timestamp column:
Before: # trace --ev bpf-output/no-inherit,name=evt/ --ev /home/acme/bpf/test_bpf_trace.c/map:channel.event=evt/ usleep 10 94631143.385 ( 0.001 ms): brk( ) = 0x555555757000 94631143.398 ( 0.003 ms): mmap(len: 4096, prot: READ|WRITE, flags: PRIVATE|ANONYMOUS, fd: -1) = 0x7ffff7ff6000 94631143.406 ( 0.004 ms): access(filename: 0xf7df9e10, mode: R ) = -1 ENOENT No such file or directory 94631143.412 ( 0.004 ms): open(filename: 0xf7df8761, flags: CLOEXEC) = 3 94631143.415 ( 0.002 ms): fstat(fd: 3, statbuf: 0x7fffffffd6b0 ) = 0 94631143.419 ( 0.003 ms): mmap(len: 106798, prot: READ, flags: PRIVATE, fd: 3) = 0x7ffff7fdb000 94631143.420 ( 0.001 ms): close(fd: 3 ) = 0 94631143.432 ( 0.004 ms): open(filename: 0xf7ff6640, flags: CLOEXEC) = 3 <SNIP> After: # trace --ev bpf-output/no-inherit,name=evt/ --ev /home/acme/bpf/test_bpf_trace.c/map:channel.event=evt/ usleep 10 0.022 ( 0.001 ms): brk( ) = 0x55d7668a6000 0.037 ( 0.003 ms): mmap(len: 4096, prot: READ|WRITE, flags: PRIVATE|ANONYMOUS, fd: -1) = 0x7f8fbeb97000 0.123 ( 0.083 ms): access(filename: 0xbe995e10, mode: R ) = -1 ENOENT No such file or directory 0.130 ( 0.004 ms): open(filename: 0xbe994761, flags: CLOEXEC) = 3 0.133 ( 0.002 ms): fstat(fd: 3, statbuf: 0x7fff6487a890 ) = 0 0.138 ( 0.003 ms): mmap(len: 106798, prot: READ, flags: PRIVATE, fd: 3) = 0x7f8fbeb7c000 0.140 ( 0.001 ms): close(fd: 3 ) = 0 0.151 ( 0.004 ms): open(filename: 0xbeb97640, flags: CLOEXEC) = 3 <SNIP> Cc: Adrian Hunter <adrian.hun...@intel.com> Cc: David Ahern <dsah...@gmail.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Milian Wolff <milian.wo...@kdab.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Wang Nan <wangn...@huawei.com> Link: http://lkml.kernel.org/n/tip-p7m8llv81iv55ekxexdp5...@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/builtin-trace.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 99daeed55a9b..d309f4535a45 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -2401,10 +2401,19 @@ static bool skip_sample(struct trace *trace, struct perf_sample *sample) } static void trace__set_base_time(struct trace *trace, - struct perf_evsel *evsel __maybe_unused, + struct perf_evsel *evsel, struct perf_sample *sample) { - if (trace->base_time == 0 && !trace->full_time) + /* + * BPF events were not setting PERF_SAMPLE_TIME, so be more robust + * and don't use sample->time unconditionally, we may end up having + * some other event in the future without PERF_SAMPLE_TIME for good + * reason, i.e. we may not be interested in its timestamps, just in + * it taking place, picking some piece of information when it + * appears in our event stream (vfs_getname comes to mind). + */ + if (trace->base_time == 0 && !trace->full_time && + (evsel->attr.sample_type & PERF_SAMPLE_TIME)) trace->base_time = sample->time; } -- 2.5.5
