[Devel] [PATCH vz10] selftests/damon: wait for the merge to apply the new max_nr_regions

[Eva Kurchatova <eva.kurchatova@virtuozzo.com>]

damon_nr_regions sleeps 0.3s after committing max_nr_regions and then
reads the number of regions back, which assumes the merge has happened
by then.  On a machine that is not idle it has not, and the test fails
on a region count that is still the old one.

Poll until the count settles instead of sleeping for a fixed time.

https://virtuozzo.atlassian.net/browse/VSTOR-132453
Feature: fix selftests
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 .../selftests/damon/damon_nr_regions.py       | 35 +++++++++++--------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/damon/damon_nr_regions.py b/tools/testing/selftests/damon/damon_nr_regions.py
index cb31cd140d22..39063ce5b27d 100755
--- a/tools/testing/selftests/damon/damon_nr_regions.py
+++ b/tools/testing/selftests/damon/damon_nr_regions.py
@@ -4,6 +4,7 @@
 import subprocess
 import time
 
+
 import _damon_sysfs
 
 def test_nr_regions(real_nr_regions, min_nr_regions, max_nr_regions):
@@ -114,27 +115,31 @@ def main():
         proc.terminate()
         print('commit failed: %s' % err)
         exit(1)
-    # wait for next merge operation is executed
-    time.sleep(0.3)
+    # wait for the merge operations to apply the new max_nr_regions
+    nr_tried_regions = 0
+    for _ in range(50):
+        time.sleep(0.1)
 
-    err = kdamonds.kdamonds[0].update_schemes_tried_regions()
-    if err is not None:
-        proc.terminate()
-        print('tried regions update failed: %s' % err)
-        exit(1)
+        err = kdamonds.kdamonds[0].update_schemes_tried_regions()
+        if err is not None:
+            proc.terminate()
+            print('tried regions update failed: %s' % err)
+            exit(1)
 
-    scheme = kdamonds.kdamonds[0].contexts[0].schemes[0]
-    if scheme.tried_regions is None:
-        proc.terminate()
-        print('tried regions is not collected')
-        exit(1)
+        scheme = kdamonds.kdamonds[0].contexts[0].schemes[0]
+        if scheme.tried_regions is None:
+            proc.terminate()
+            print('tried regions is not collected')
+            exit(1)
+
+        nr_tried_regions = len(scheme.tried_regions)
+        if 0 < nr_tried_regions <= 7:
+            break
+    proc.terminate()
 
-    nr_tried_regions = len(scheme.tried_regions)
     if nr_tried_regions <= 0:
-        proc.terminate()
         print('tried regions is not created')
         exit(1)
-    proc.terminate()
 
     if nr_tried_regions > 7:
         print('fail online-tuned max_nr_regions: %d > 7' % nr_tried_regions)
-- 
2.55.0