Improve PSI files validation (fix #74)

tools/psi-top

@@ -73,8 +73,12 @@ else:
 
 psi_support = os.path.exists(psi_path)
 
-if not psi_support:
-    print('PSI is not supported, /proc/pressure/memory does not exist. Exit.')
+
+try:
+    psi_path_to_metrics(psi_path)
+except Exception as e:
+    print('ERROR: {}'.format(e))
+    print('PSI metrics are not provided by the kernel. Exit.')
     exit(1)
 
 

tools/psi2log

@@ -193,9 +193,12 @@ if log_file is not None:
     log('log file: {}'.format(log_file))
 
 
-if not os.path.exists('/proc/pressure'):
-    log('ERROR: /proc/pressure does not exist, PSI is not supported, exit')
-    exit()
+try:
+    psi_file_mem_to_metrics('/proc/pressure/memory')
+except Exception as e:
+    print('ERROR: {}'.format(e))
+    print('PSI metrics are not provided by the kernel. Exit.')
+    exit(1)
 
 
 if target == 'SYSTEM_WIDE':