tools/kvm_stat: separate drilldown and fields filtering

Drilldown (i.e. toggle display of child trace events) was implemented by
overriding the fields filter. This resulted in inconsistencies: E.g. when
drilldown was not active, adding a filter that also matches child trace
events would not only filter fields according to the filter, but also add
in the child trace events matching the filter. E.g. on x86, setting
'kvm_userspace_exit' as the fields filter after startup would result in
display of kvm_userspace_exit(DCR), although that wasn't previously
present - not exactly what one would expect from a filter.
This patch addresses the issue by keeping drilldown and fields filter
separate. While at it, we also fix a PEP8 issue by adding a blank line
at one place (since we're in the area...).
We implement this by adding a framework that also allows to define a
taxonomy among the debugfs events to identify child trace events. I.e.
drilldown using 'x' can now also work with debugfs. A respective parent-
child relationship is only known for S390 at the moment, but could be
added adjusting other platforms' ARCH.dbg_is_child() methods
accordingly.
Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -228,6 +228,7 @@ IOCTL_NUMBERS = {
 }
 
 ENCODING = locale.getpreferredencoding(False)
+TRACE_FILTER = re.compile(r'^[^\(]*$')
 
 
 class Arch(object):
@@ -260,6 +261,11 @@ class Arch(object):
                     return ArchX86(SVM_EXIT_REASONS)
                 return
 
+    def tracepoint_is_child(self, field):
+        if (TRACE_FILTER.match(field)):
+            return None
+        return field.split('(', 1)[0]
+
 
 class ArchX86(Arch):
     def __init__(self, exit_reasons):
@@ -267,6 +273,10 @@ class ArchX86(Arch):
         self.ioctl_numbers = IOCTL_NUMBERS
         self.exit_reasons = exit_reasons
 
+    def debugfs_is_child(self, field):
+        """ Returns name of parent if 'field' is a child, None otherwise """
+        return None
+
 
 class ArchPPC(Arch):
     def __init__(self):
@@ -282,6 +292,10 @@ class ArchPPC(Arch):
         self.ioctl_numbers['SET_FILTER'] = 0x80002406 | char_ptr_size << 16
         self.exit_reasons = {}
 
+    def debugfs_is_child(self, field):
+        """ Returns name of parent if 'field' is a child, None otherwise """
+        return None
+
 
 class ArchA64(Arch):
     def __init__(self):
@@ -289,6 +303,10 @@ class ArchA64(Arch):
         self.ioctl_numbers = IOCTL_NUMBERS
         self.exit_reasons = AARCH64_EXIT_REASONS
 
+    def debugfs_is_child(self, field):
+        """ Returns name of parent if 'field' is a child, None otherwise """
+        return None
+
 
 class ArchS390(Arch):
     def __init__(self):
@@ -296,6 +314,12 @@ class ArchS390(Arch):
         self.ioctl_numbers = IOCTL_NUMBERS
         self.exit_reasons = None
 
+    def debugfs_is_child(self, field):
+        """ Returns name of parent if 'field' is a child, None otherwise """
+        if field.startswith('instruction_'):
+            return 'exit_instruction'
+
+
 ARCH = Arch.get_arch()
 
 
@@ -472,6 +496,10 @@ class Event(object):
 
 class Provider(object):
     """Encapsulates functionalities used by all providers."""
+    def __init__(self, pid):
+        self.child_events = False
+        self.pid = pid
+
     @staticmethod
     def is_field_wanted(fields_filter, field):
         """Indicate whether field is valid according to fields_filter."""
@@ -499,7 +527,7 @@ class TracepointProvider(Provider):
         self.group_leaders = []
         self.filters = self._get_filters()
         self.update_fields(fields_filter)
-        self.pid = pid
+        super(TracepointProvider, self).__init__(pid)
 
     @staticmethod
     def _get_filters():
@@ -519,7 +547,7 @@ class TracepointProvider(Provider):
         return filters
 
     def _get_available_fields(self):
-        """Returns a list of available event's of format 'event name(filter
+        """Returns a list of available events of format 'event name(filter
         name)'.
 
         All available events have directories under
@@ -547,7 +575,8 @@ class TracepointProvider(Provider):
     def update_fields(self, fields_filter):
         """Refresh fields, applying fields_filter"""
         self.fields = [field for field in self._get_available_fields()
-                       if self.is_field_wanted(fields_filter, field)]
+                       if self.is_field_wanted(fields_filter, field) or
+                       ARCH.tracepoint_is_child(field)]
 
     @staticmethod
     def _get_online_cpus():
@@ -668,8 +697,12 @@ class TracepointProvider(Provider):
         ret = defaultdict(int)
         for group in self.group_leaders:
             for name, val in group.read().items():
-                if name in self._fields:
-                    ret[name] += val
+                if name not in self._fields:
+                    continue
+                parent = ARCH.tracepoint_is_child(name)
+                if parent:
+                    name += ' ' + parent
+                ret[name] += val
         return ret
 
     def reset(self):
@@ -687,7 +720,7 @@ class DebugfsProvider(Provider):
         self._baseline = {}
         self.do_read = True
         self.paths = []
-        self.pid = pid
+        super(DebugfsProvider, self).__init__(pid)
         if include_past:
             self._restore()
 
@@ -702,7 +735,8 @@ class DebugfsProvider(Provider):
     def update_fields(self, fields_filter):
         """Refresh fields, applying fields_filter"""
         self._fields = [field for field in self._get_available_fields()
-                        if self.is_field_wanted(fields_filter, field)]
+                        if self.is_field_wanted(fields_filter, field) or
+                        ARCH.debugfs_is_child(field)]
 
     @property
     def fields(self):
@@ -763,14 +797,15 @@ class DebugfsProvider(Provider):
                     self._baseline[key] = 0
                 if self._baseline.get(key, -1) == -1:
                     self._baseline[key] = value
-                increment = (results.get(field, 0) + value -
-                             self._baseline.get(key, 0))
-                if by_guest:
-                    pid = key.split('-')[0]
-                    if pid in results:
-                        results[pid] += increment
-                    else:
-                        results[pid] = increment
+                parent = ARCH.debugfs_is_child(field)
+                if parent:
+                    field = field + ' ' + parent
+                else:
+                    if by_guest:
+                        field = key.split('-')[0]    # set 'field' to 'pid'
+                increment = value - self._baseline.get(key, 0)
+                if field in results:
+                    results[field] += increment
                 else:
                     results[field] = increment
 
@@ -812,6 +847,7 @@ class Stats(object):
         self._pid_filter = options.pid
         self._fields_filter = options.fields
         self.values = {}
+        self._child_events = False
 
     def _get_providers(self, options):
         """Returns a list of data providers depending on the passed options."""
@@ -860,12 +896,29 @@ class Stats(object):
             for provider in self.providers:
                 provider.pid = self._pid_filter
 
+    @property
+    def child_events(self):
+        return self._child_events
+
+    @child_events.setter
+    def child_events(self, val):
+        self._child_events = val
+        for provider in self.providers:
+            provider.child_events = val
+
     def get(self, by_guest=0):
         """Returns a dict with field -> (value, delta to last value) of all
-        provider data."""
+        provider data.
+        Key formats:
+          * plain: 'key' is event name
+          * child-parent: 'key' is in format '<child> <parent>'
+          * pid: 'key' is the pid of the guest, and the record contains the
+               aggregated event data
+        These formats are generated by the providers, and handled in class TUI.
+        """
         for provider in self.providers:
             new = provider.read(by_guest=by_guest)
-            for key in new if by_guest else provider.fields:
+            for key in new:
                 oldval = self.values.get(key, EventStat(0, 0)).value
                 newval = new.get(key, 0)
                 newdelta = newval - oldval
@@ -898,10 +951,10 @@ class Stats(object):
         self.get(to_pid)
         return 0
 
+
 DELAY_DEFAULT = 3.0
 MAX_GUEST_NAME_LEN = 48
 MAX_REGEX_LEN = 44
-DEFAULT_REGEX = r'^[^\(]*$'
 SORT_DEFAULT = 0
 
 
@@ -1031,14 +1084,6 @@ class Tui(object):
 
         return name
 
-    def _update_drilldown(self):
-        """Sets or removes a filter that only allows fields without braces."""
-        if not self.stats.fields_filter:
-            self.stats.fields_filter = DEFAULT_REGEX
-
-        elif self.stats.fields_filter == DEFAULT_REGEX:
-            self.stats.fields_filter = None
-
     def _update_pid(self, pid):
         """Propagates pid selection to stats object."""
         self.screen.addstr(4, 1, 'Updating pid filter...')
@@ -1060,8 +1105,7 @@ class Tui(object):
                                .format(pid, gname), curses.A_BOLD)
         else:
             self.screen.addstr(0, 0, 'kvm statistics - summary', curses.A_BOLD)
-        if self.stats.fields_filter and self.stats.fields_filter \
-           != DEFAULT_REGEX:
+        if self.stats.fields_filter:
             regex = self.stats.fields_filter
             if len(regex) > MAX_REGEX_LEN:
                 regex = regex[:MAX_REGEX_LEN] + '...'
@@ -1077,6 +1121,9 @@ class Tui(object):
         self.screen.refresh()
 
     def _refresh_body(self, sleeptime):
+        def is_child_field(field):
+            return field.find('(') != -1
+
         row = 3
         self.screen.move(row, 0)
         self.screen.clrtobot()
@@ -1084,7 +1131,11 @@ class Tui(object):
         total = 0.
         ctotal = 0.
         for key, values in stats.items():
-            if key.find('(') == -1:
+            if self._display_guests:
+                if self.get_gname_from_pid(key):
+                    total += values.value
+                continue
+            if not key.find(' ') != -1:
                 total += values.value
             else:
                 ctotal += values.value
@@ -1101,19 +1152,26 @@ class Tui(object):
                 # sort by overall value
                 return v.value
 
+        sorted_items = sorted(stats.items(), key=sortkey, reverse=True)
+
+        # print events
         tavg = 0
-        for key, values in sorted(stats.items(), key=sortkey, reverse=True):
+        for key, values in sorted_items:
             if row >= self.screen.getmaxyx()[0] - 1:
                 break
-            if not values.value and not values.delta:
-                break
+            if values == (0, 0):
+                continue
+            if not self.stats.child_events and key.find(' ') != -1:
+                continue
             if values.value is not None:
                 cur = int(round(values.delta / sleeptime)) if values.delta else ''
                 if self._display_guests:
                     key = self.get_gname_from_pid(key)
-                self.screen.addstr(row, 1, '%-40s %10d%7.1f %8s' %
-                                   (key, values.value, values.value * 100 / total,
-                                    cur))
+                    if not key:
+                        continue
+                self.screen.addstr(row, 1, '%-40s %10d%7.1f %8s' % (key
+                                   .split(' ')[0], values.value,
+                                   values.value * 100 / total, cur))
                 if cur != '' and key.find('(') == -1:
                     tavg += cur
             row += 1
@@ -1189,7 +1247,7 @@ class Tui(object):
             regex = self.screen.getstr().decode(ENCODING)
             curses.noecho()
             if len(regex) == 0:
-                self.stats.fields_filter = DEFAULT_REGEX
+                self.stats.fields_filter = ''
                 self._refresh_header()
                 return
             try:
@@ -1307,7 +1365,7 @@ class Tui(object):
                         self._display_guests = not self._display_guests
                     self._refresh_header()
                 if char == 'c':
-                    self.stats.fields_filter = DEFAULT_REGEX
+                    self.stats.fields_filter = ''
                     self._refresh_header(0)
                     self._update_pid(0)
                 if char == 'f':
@@ -1332,9 +1390,7 @@ class Tui(object):
                     curses.curs_set(0)
                     sleeptime = self._delay_initial
                 if char == 'x':
-                    self._update_drilldown()
-                    # prevents display of current values on next refresh
-                    self.stats.get(self._display_guests)
+                    self.stats.child_events = not self.stats.child_events
             except KeyboardInterrupt:
                 break
             except curses.error:
@@ -1348,7 +1404,8 @@ def batch(stats):
         time.sleep(1)
         s = stats.get()
         for key, values in sorted(s.items()):
-            print('%-42s%10d%10d' % (key, values.value, values.delta))
+            print('%-42s%10d%10d' % (key.split(' ')[0], values.value,
+                  values.delta))
     except KeyboardInterrupt:
         pass
 
@@ -1359,7 +1416,7 @@ def log(stats):
 
     def banner():
         for key in keys:
-            print(key, end=' ')
+            print(key.split(' ')[0], end=' ')
         print()
 
     def statline():
@@ -1470,7 +1527,7 @@ Press any other key to refresh statistics immediately.
                          )
     optparser.add_option('-f', '--fields',
                          action='store',
-                         default=DEFAULT_REGEX,
+                         default='',
                          dest='fields',
                          help='''fields to display (regex)
                                  "-f help" for a list of available events''',