rtla/tests: Test setting default options

Add function to test engine to test with pre-set osnoise options, and
use it to test whether osnoise period (as an example) is set correctly.

The test works by pre-setting a high period of 10 minutes and stop on
threshold. Thus, it is easy to check whether rtla is properly resetting
the period to default: if it is, the test will complete on time, since
the first sample will overflow the threshold. If not, it will time out.

Cc: Luis Goncalves <lgoncalv@redhat.com>
Link: https://lore.kernel.org/20250320092500.101385-7-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Reviewed-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/tracing/rtla/tests/engine.sh

@@ -61,6 +61,32 @@ check() {
 	fi
 }
 
+check_with_osnoise_options() {
+	# Do the same as "check", but with pre-set osnoise options.
+	# Note: rtla should reset the osnoise options, this is used to test
+	# if it indeed does so.
+	# Save original arguments
+	arg1=$1
+	arg2=$2
+
+	# Apply osnoise options (if not dry run)
+	if [ -n "$TEST_COUNT" ]
+	then
+		[ "$NO_RESET_OSNOISE" == 1 ] || reset_osnoise
+		shift
+		while shift
+		do
+			[ "$1" == "" ] && continue
+			option=$(echo $1 | cut -d '=' -f 1)
+			value=$(echo $1 | cut -d '=' -f 2)
+			echo "option: $option, value: $value"
+			echo "$value" > "/sys/kernel/tracing/osnoise/$option" || return 1
+		done
+	fi
+
+	NO_RESET_OSNOISE=1 check "$arg1" "$arg2"
+}
+
 set_timeout() {
 	TIMEOUT="timeout -v -k 15s $1"
 }

tools/tracing/rtla/tests/osnoise.t

@@ -16,4 +16,10 @@ check "verify the  --trace param" \
 check "verify the --entries/-E param" \
 	"osnoise hist -P F:1 -c 0 -r 900000 -d 1M -b 10 -E 25"
 
+# Test setting default period by putting an absurdly high period
+# and stopping on threshold.
+# If default period is not set, this will time out.
+check_with_osnoise_options "apply default period" \
+	"osnoise hist -s 1" period_us=600000000
+
 test_end