perf script: Support relative time

When comparing time stamps in 'perf script' traces it can be annoying to
work with the full perf time stamps.

Add a --reltime option that displays time stamps relative to the trace
start to make it easier to read the traces.

Note: not currently supported for --time. Report an error in this
case.

Before:

  % perf script
      swapper 0 [000] 245402.891216:    1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000] 245402.891223:    1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000] 245402.891227:    5 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000] 245402.891231:   41 cycles:ppp: ffffffffa0068816 native_write_msr+0x6 ([kernel.kallsyms])
      swapper 0 [000] 245402.891235:  355 cycles:ppp: ffffffffa000dd51 intel_bts_enable_local+0x21 ([kernel.kallsyms])
      swapper 0 [000] 245402.891239: 3084 cycles:ppp: ffffffffa0a0150a end_repeat_nmi+0x48 ([kernel.kallsyms])

After:

  % perf script --reltime

      swapper 0 [000]     0.000000:    1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000]     0.000006:    1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000]     0.000010:    5 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
      swapper 0 [000]     0.000014:   41 cycles:ppp: ffffffffa0068816 native_write_msr+0x6 ([kernel.kallsyms])
      swapper 0 [000]     0.000018:  355 cycles:ppp: ffffffffa000dd51 intel_bts_enable_local+0x21 ([kernel.kallsyms])
      swapper 0 [000]     0.000022: 3084 cycles:ppp: ffffffffa0a0150a end_repeat_nmi+0x48 ([kernel.kallsyms])

Committer notes:

Do not use 'time' as the name of a variable, as this breaks the build on
older glibcs:

  cc1: warnings being treated as errors
  builtin-script.c: In function 'perf_sample__fprintf_start':
  builtin-script.c:691: warning: declaration of 'time' shadows a global declaration
  /usr/include/time.h:187: warning: shadowed declaration is here

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
LPU-Reference: 20190314225002.30108-8-andi@firstfloor.org
Link: https://lkml.kernel.org/n/tip-bpahyi6pr9r399mvihu65fvc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 2f93d60c5a17..61cfd8f70989 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -53,6 +53,8 @@
 
 static char const               *script_name;
 static char const               *generate_script_lang;
+static bool                     reltime;
+static u64                      initial_time;
 static bool                     debug_mode;
 static u64                      last_timestamp;
 static u64                      nr_unordered;
@@ -686,7 +688,13 @@ static int perf_sample__fprintf_start(struct perf_sample *sample,
         }
 
         if (PRINT_FIELD(TIME)) {
-                nsecs = sample->time;
+                u64 t = sample->time;
+                if (reltime) {
+                        if (!initial_time)
+                                initial_time = sample->time;
+                        t = sample->time - initial_time;
+                }
+                nsecs = t;
                 secs = nsecs / NSEC_PER_SEC;
                 nsecs -= secs * NSEC_PER_SEC;
 
@@ -694,7 +702,7 @@ static int perf_sample__fprintf_start(struct perf_sample *sample,
                         printed += fprintf(fp, "%5lu.%09llu: ", secs, nsecs);
                 else {
                         char sample_time[32];
-                        timestamp__scnprintf_usec(sample->time, sample_time, sizeof(sample_time));
+                        timestamp__scnprintf_usec(t, sample_time, sizeof(sample_time));
                         printed += fprintf(fp, "%12s: ", sample_time);
                 }
         }
@@ -3413,6 +3421,7 @@ int cmd_script(int argc, const char **argv)
                      "Set the maximum stack depth when parsing the callchain, "
                      "anything beyond the specified depth will be ignored. "
                      "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
+        OPT_BOOLEAN(0, "reltime", &reltime, "Show time stamps relative to start"),
         OPT_BOOLEAN('I', "show-info", &show_full_info,
                     "display extended information from perf.data file"),
         OPT_BOOLEAN('\0', "show-kernel-path", &symbol_conf.show_kernel_path,
@@ -3487,6 +3496,11 @@ int cmd_script(int argc, const char **argv)
                 }
         }
 
+        if (script.time_str && reltime) {
+                fprintf(stderr, "Don't combine --reltime with --time\n");
+                return -1;
+        }
+
         if (itrace_synth_opts.callchain &&
             itrace_synth_opts.callchain_sz > scripting_max_stack)
                 scripting_max_stack = itrace_synth_opts.callchain_sz;