tools/kvm_stat: add command line switch '-s' to set update interval

This now controls both, the refresh rate of the interactive mode as well
as the logging mode. Which, as a consequence, means that the default of
logging mode is now 3s, too (use command line switch '-s' to adjust to
your liking).

Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Message-Id: <20200306114250.57585-4-raspl@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -974,15 +974,17 @@ DELAY_DEFAULT = 3.0
 MAX_GUEST_NAME_LEN = 48
 MAX_REGEX_LEN = 44
 SORT_DEFAULT = 0
+MIN_DELAY = 0.1
+MAX_DELAY = 25.5
 
 
 class Tui(object):
     """Instruments curses to draw a nice text ui."""
-    def __init__(self, stats):
+    def __init__(self, stats, opts):
         self.stats = stats
         self.screen = None
         self._delay_initial = 0.25
-        self._delay_regular = DELAY_DEFAULT
+        self._delay_regular = opts.set_delay
         self._sorting = SORT_DEFAULT
         self._display_guests = 0
 
@@ -1282,7 +1284,8 @@ class Tui(object):
                '   p     filter by guest name/PID',
                '   q     quit',
                '   r     reset stats',
-               '   s     set update interval',
+               '   s     set delay between refreshs (value range: '
+               '%s-%s secs)' % (MIN_DELAY, MAX_DELAY),
                '   x     toggle reporting of stats for individual child trace'
                ' events',
                'Any other key refreshes statistics immediately')
@@ -1348,11 +1351,9 @@ class Tui(object):
             try:
                 if len(val) > 0:
                     delay = float(val)
-                    if delay < 0.1:
+                    err = is_delay_valid(delay)
-                        msg = '"' + str(val) + '": Value must be >=0.1'
+                    if err is not None:
-                        continue
+                        msg = err
-                    if delay > 25.5:
-                        msg = '"' + str(val) + '": Value must be <=25.5'
                         continue
                 else:
                     delay = DELAY_DEFAULT
@@ -1488,7 +1489,7 @@ def batch(stats):
         pass
 
 
-def log(stats):
+def log(stats, opts):
     """Prints statistics as reiterating key block, multiple value blocks."""
     keys = sorted(stats.get().keys())
 
@@ -1506,7 +1507,7 @@ def log(stats):
     banner_repeat = 20
     while True:
         try:
-            time.sleep(1)
+            time.sleep(opts.set_delay)
             if line % banner_repeat == 0:
                 banner()
             statline()
@@ -1515,6 +1516,16 @@ def log(stats):
             break
 
 
+def is_delay_valid(delay):
+    """Verify delay is in valid value range."""
+    msg = None
+    if delay < MIN_DELAY:
+        msg = '"' + str(delay) + '": Delay must be >=%s' % MIN_DELAY
+    if delay > MAX_DELAY:
+        msg = '"' + str(delay) + '": Delay must be <=%s' % MAX_DELAY
+    return msg
+
+
 def get_options():
     """Returns processed program arguments."""
     description_text = """
@@ -1604,6 +1615,13 @@ Press any other key to refresh statistics immediately.
                            default=0,
                            help='restrict statistics to pid',
                            )
+    argparser.add_argument('-s', '--set-delay',
+                           type=float,
+                           default=DELAY_DEFAULT,
+                           metavar='DELAY',
+                           help='set delay between refreshs (value range: '
+                                '%s-%s secs)' % (MIN_DELAY, MAX_DELAY),
+                           )
     argparser.add_argument('-t', '--tracepoints',
                            action='store_true',
                            default=False,
@@ -1675,6 +1693,10 @@ def main():
         sys.stderr.write('Did you use a (unsupported) tid instead of a pid?\n')
         sys.exit('Specified pid does not exist.')
 
+    err = is_delay_valid(options.set_delay)
+    if err is not None:
+        sys.exit('Error: ' + err)
+
     stats = Stats(options)
 
     if options.fields == 'help':
@@ -1686,9 +1708,9 @@ def main():
         sys.exit(0)
 
     if options.log:
-        log(stats)
+        log(stats, options)
     elif not options.once:
-        with Tui(stats) as tui:
+        with Tui(stats, options) as tui:
             tui.show_stats()
     else:
         batch(stats)

tools/kvm/kvm_stat/kvm_stat.txt

@@ -92,6 +92,10 @@ OPTIONS
 --pid=<pid>::
 	limit statistics to one virtual machine (pid)
 
+-s::
+--set-delay::
+        set delay between refreshs (value range: 0.1-25.5 secs)
+
 -t::
 --tracepoints::
         retrieve statistics from tracepoints