perf stat: Add --interval-clear option

Adding --interval-clear option to clear the screen before next interval.

Committer testing:

  # perf stat -I 1000 --interval-clear

And, as expected, it behaves almost like:

  # watch -n 0 perf stat -a sleep 1

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180606221513.11302-4-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 12 insertions, 2 deletions

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 5dfe102fb5b5..b10a90b6a718 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -178,6 +178,9 @@ Print count deltas for fixed number of times.
 This option should be used together with "-I" option.
         example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
 
+--interval-clear::
+Clear the screen before next interval.
+
 --timeout msecs::
 Stop the 'perf stat' session and print count deltas after N milliseconds (minimum: 10 ms).
 This option is not supported with the "-I" option.
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 096ccb25c11f..f1532e3ac7d7 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -65,6 +65,7 @@
 #include "util/tool.h"
 #include "util/string2.h"
 #include "util/metricgroup.h"
+#include "util/top.h"
 #include "asm/bug.h"
 
 #include <linux/time64.h>
@@ -173,6 +174,7 @@ static struct cpu_map		*aggr_map;
 static aggr_get_id_t            aggr_get_id;
 static bool                     append_file;
 static bool                     interval_count;
+static bool                     interval_clear;
 static const char               *output_name;
 static int                      output_fd;
 static int                      print_free_counters_hint;
@@ -1704,9 +1706,12 @@ static void print_interval(char *prefix, struct timespec *ts)
         FILE *output = stat_config.output;
         static int num_print_interval;
 
+        if (interval_clear)
+                puts(CONSOLE_CLEAR);
+
         sprintf(prefix, "%6lu.%09lu%s", ts->tv_sec, ts->tv_nsec, csv_sep);
 
-        if (num_print_interval == 0 && !csv_output) {
+        if ((num_print_interval == 0 && !csv_output) || interval_clear) {
                 switch (stat_config.aggr_mode) {
                 case AGGR_SOCKET:
                         fprintf(output, "#           time socket cpus");
@@ -1738,7 +1743,7 @@ static void print_interval(char *prefix, struct timespec *ts)
                 }
         }
 
-        if (num_print_interval == 0 && metric_only)
+        if ((num_print_interval == 0 && metric_only) || interval_clear)
                 print_metric_headers(" ", true);
         if (++num_print_interval == 25)
                 num_print_interval = 0;
@@ -2057,6 +2062,8 @@ static const struct option stat_options[] = {
                     "(overhead is possible for values <= 100ms)"),
         OPT_INTEGER(0, "interval-count", &stat_config.times,
                     "print counts for fixed number of times"),
+        OPT_BOOLEAN(0, "interval-clear", &interval_clear,
+                    "clear screen in between new interval"),
         OPT_UINTEGER(0, "timeout", &stat_config.timeout,
                     "stop workload and print counts after a timeout period in ms (>= 10ms)"),
         OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,