Add a command line argument, --jobs, to specify how many tests can
execute concurrently. Set default to 1.

Example:
  python3 runner --test-dirs tests -j 10

Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
 .../testing/selftests/kvm/runner/__main__.py  |  6 ++++
 .../selftests/kvm/runner/test_runner.py       | 28 +++++++++++++------
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/runner/__main__.py b/tools/testing/selftests/kvm/runner/__main__.py
index b27a41e86271..b98f72c9f7ee 100644
--- a/tools/testing/selftests/kvm/runner/__main__.py
+++ b/tools/testing/selftests/kvm/runner/__main__.py
@@ -54,6 +54,12 @@ def cli():
                         default=False,
                         help="Appends timestamp to the output directory.")
 
+    parser.add_argument("-j",
+                        "--jobs",
+                        default=1,
+                        type=int,
+                        help="Maximum number of tests that can be run concurrently. (Default: 1)")
+
     return parser.parse_args()
 
 
diff --git a/tools/testing/selftests/kvm/runner/test_runner.py b/tools/testing/selftests/kvm/runner/test_runner.py
index b9101f0e0432..92eec18fe5c6 100644
--- a/tools/testing/selftests/kvm/runner/test_runner.py
+++ b/tools/testing/selftests/kvm/runner/test_runner.py
@@ -4,6 +4,8 @@
 # Author: vipinsh@google.com (Vipin Sharma)
 
 import logging
+import concurrent.futures
+
 from selftest import Selftest
 from selftest import SelftestStatus
 
@@ -14,11 +16,16 @@ class TestRunner:
     def __init__(self, testcases, args):
         self.tests = []
         self.output_dir = args.output
+        self.jobs = args.jobs
 
         for testcase in testcases:
             self.tests.append(Selftest(testcase, args.path, args.timeout,
                                        args.output))
 
+    def _run_test(self, test):
+        test.run()
+        return test
+
     def _log_result(self, test_result):
         logger.info("*** stdout ***\n" + test_result.stdout)
         logger.info("*** stderr ***\n" + test_result.stderr)
@@ -28,12 +35,17 @@ class TestRunner:
     def start(self):
         ret = 0
 
-        for test in self.tests:
-            test.run()
-            self._log_result(test)
-
-            if (test.status not in [SelftestStatus.PASSED,
-                                    SelftestStatus.NO_RUN,
-                                    SelftestStatus.SKIPPED]):
-                ret = 1
+        with concurrent.futures.ProcessPoolExecutor(max_workers=self.jobs) as executor:
+            all_futures = []
+            for test in self.tests:
+                future = executor.submit(self._run_test, test)
+                all_futures.append(future)
+
+            for future in concurrent.futures.as_completed(all_futures):
+                test_result = future.result()
+                self._log_result(test_result)
+                if (test_result.status not in [SelftestStatus.PASSED,
+                                               SelftestStatus.NO_RUN,
+                                               SelftestStatus.SKIPPED]):
+                    ret = 1
         return ret
-- 
2.51.0.618.g983fd99d29-goog