[PATCH v1 08/10] perf, tools, script: Support relative time

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

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])

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/Documentation/perf-script.txt |  3 +++
 tools/perf/builtin-script.c              | 18 ++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 2e19fd7ffe35..9b0d04dd2a61 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -380,6 +380,9 @@ include::itrace.txt[]
 	Set the maximum number of program blocks to print with brstackasm for
 	each sample.
 
+--reltime::
+	Print time stamps relative to trace start.
+
 --per-event-dump::
 	Create per event files with a "perf.data.EVENT.dump" name instead of
         printing to stdout, useful, for instance, for generating flamegraphs.
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 111787e83784..9664db79dc5a 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 time = sample->time;
+		if (reltime) {
+			if (!initial_time)
+				initial_time = sample->time;
+			time = sample->time - initial_time;
+		}
+		nsecs = time;
 		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(time, sample_time, sizeof(sample_time));
 			printed += fprintf(fp, "%12s: ", sample_time);
 		}
 	}
@@ -3386,6 +3394,7 @@ 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,
@@ -3460,6 +3469,11 @@ 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;
-- 
2.20.1