selftests/damon/_damon_sysfs: support DAMOS apply interval

Update the test-purpose DAMON sysfs control Python module to support DAMOS
apply interval.

Link: https://lkml.kernel.org/r/20240207203134.69976-4-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/damon/_damon_sysfs.py

@@ -114,6 +114,7 @@ class Damos:
     action = None
     access_pattern = None
     quota = None
+    apply_interval_us = None
     # todo: Support watermarks, stats, tried_regions
     idx = None
     context = None
@@ -121,12 +122,13 @@ class Damos:
     stats = None
 
     def __init__(self, action='stat', access_pattern=DamosAccessPattern(),
-                 quota=DamosQuota()):
+                 quota=DamosQuota(), apply_interval_us=0):
         self.action = action
         self.access_pattern = access_pattern
         self.access_pattern.scheme = self
         self.quota = quota
         self.quota.scheme = self
+        self.apply_interval_us = apply_interval_us
 
     def sysfs_dir(self):
         return os.path.join(
@@ -139,6 +141,11 @@ class Damos:
         err = self.access_pattern.stage()
         if err != None:
             return err
+        err = write_file(os.path.join(self.sysfs_dir(), 'apply_interval_us'),
+                         '%d' % self.apply_interval_us)
+        if err != None:
+            return err
+
         err = self.quota.stage()
         if err != None:
             return err