perf stat: Clear sample_(type|period) for counting

Clear sample_(type|period) for counting, as it only confuses debug
output with unwanted sampling details:

Before:

$ sudo perf stat -e 'raw_syscalls:sys_enter' -vv ls
------------------------------------------------------------
perf_event_attr:
type 2
size 112
config 0x11
{ sample_period, sample_freq } 1
sample_type TIME|CPU|PERIOD|RAW
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
enable_on_exec 1
exclude_guest 1
...

After:
$ sudo perf stat -e 'raw_syscalls:sys_enter' -vv ls
------------------------------------------------------------
perf_event_attr:
type 2
size 112
config 0x11
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
enable_on_exec 1
exclude_guest 1
...

Signed-off-by: Jiri Olsa <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-stat.c

···
 
 	attr->inherit = !no_inherit;
 
+	/*
+	 * Some events get initialized with sample_(period/type) set,
+	 * like tracepoints. Clear it up for counting.
+	 */
+	attr->sample_period = 0;
+	attr->sample_type   = 0;
+
 	if (target__has_cpu(&target))
 		return perf_evsel__open_per_cpu(evsel, perf_evsel__cpus(evsel));