[PATCH] perf script: add option to display time change between events

[David Ahern <dsahern@gmail.com>]

Add a 'dt' field option to show time change between events dumped to user:

         swapper     0 [000] 0.003780: netif_receive_skb: dev=wlan0 skbaddr=...
            vpnc 23605 [000] 0.000347: netif_rx: dev=tun0 skbaddr=...
            vpnc 23605 [000] 0.000007: netif_receive_skb: dev=tun0 skbaddr=...
 thunderbird-bin 22435 [000] 0.001043: net_dev_queue: dev=tun0 skbaddr=...
 thunderbird-bin 22435 [000] 0.000012: net_dev_xmit: dev=tun0 skbaddr=...

Signed-off-by: David Ahern <dsahern@gmail.com>
---
 tools/perf/Documentation/perf-script.txt |    2 +-
 tools/perf/builtin-script.c              |   20 +++++++++++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index db01786..4f996ab 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -115,7 +115,7 @@ OPTIONS
 -f::
 --fields::
         Comma separated list of fields to print. Options are:
-        comm, tid, pid, time, cpu, event, trace, ip, sym, dso, addr.
+        comm, tid, pid, time, dt, cpu, event, trace, ip, sym, dso, addr.
         Field list can be prepended with the type, trace, sw or hw,
         to indicate to which event type the field list applies.
         e.g., -f sw:comm,tid,time,ip,sym  and -f trace:time,cpu,trace
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 09024ec..541b30a 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -37,6 +37,7 @@ enum perf_output_field {
 	PERF_OUTPUT_SYM             = 1U << 8,
 	PERF_OUTPUT_DSO             = 1U << 9,
 	PERF_OUTPUT_ADDR            = 1U << 10,
+	PERF_OUTPUT_DT              = 1U << 11,
 };
 
 struct output_option {
@@ -54,6 +55,7 @@ struct output_option {
 	{.str = "sym",   .field = PERF_OUTPUT_SYM},
 	{.str = "dso",   .field = PERF_OUTPUT_DSO},
 	{.str = "addr",  .field = PERF_OUTPUT_ADDR},
+	{.str = "dt",    .field = PERF_OUTPUT_DT},
 };
 
 /* default set to maintain compatibility with current format */
@@ -207,6 +209,11 @@ static int perf_evsel__check_attr(struct perf_evsel *evsel,
 				       PERF_OUTPUT_TIME))
 		return -EINVAL;
 
+	if (PRINT_FIELD(DT) &&
+		perf_event_attr__check_stype(attr, PERF_SAMPLE_TIME, "DT",
+				       PERF_OUTPUT_DT))
+		return -EINVAL;
+
 	if (PRINT_FIELD(CPU) &&
 		perf_event_attr__check_stype(attr, PERF_SAMPLE_CPU, "CPU",
 				       PERF_OUTPUT_CPU))
@@ -288,6 +295,17 @@ static void print_sample_start(struct perf_sample *sample,
 		printf("%5lu.%06lu: ", secs, usecs);
 	}
 
+	if (PRINT_FIELD(DT)) {
+		static u64 prev_sample_time;
+
+		nsecs =  prev_sample_time ? sample->time - prev_sample_time : 0;
+		prev_sample_time = sample->time;
+		secs = nsecs / NSECS_PER_SEC;
+		nsecs -= secs * NSECS_PER_SEC;
+		usecs = nsecs / NSECS_PER_USEC;
+		printf("%lu.%06lu: ", secs, usecs);
+	}
+
 	if (PRINT_FIELD(EVNAME)) {
 		if (attr->type == PERF_TYPE_TRACEPOINT) {
 			type = trace_parse_common_type(sample->raw_data);
@@ -1080,7 +1098,7 @@ static const struct option options[] = {
 	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
 		    "Look for files with symbols relative to this directory"),
 	OPT_CALLBACK('f', "fields", NULL, "str",
-		     "comma separated output fields prepend with 'type:'. Valid types: hw,sw,trace,raw. Fields: comm,tid,pid,time,cpu,event,trace,ip,sym,dso,addr",
+		     "comma separated output fields prepend with 'type:'. Valid types: hw,sw,trace,raw. Fields: comm,tid,pid,time,dt,cpu,event,trace,ip,sym,dso,addr",
 		     parse_output_fields),
 	OPT_STRING('c', "cpu", &cpu_list, "cpu", "list of cpus to profile"),
 
-- 
1.7.6