tools: kvm_stat: Add comments (fabc7128) · Commits · 戴 / test

tools/kvm/kvm_stat/kvm_stat

+159 −2

Original line number	Original line	Diff line number	Diff line
	@@ -10,6 +10,15 @@
	#		#
	# This work is licensed under the terms of the GNU GPL, version 2. See		# This work is licensed under the terms of the GNU GPL, version 2. See
	# the COPYING file in the top-level directory.		# the COPYING file in the top-level directory.
			"""The kvm_stat module outputs statistics about running KVM VMs

			Three different ways of output formatting are available:
			- as a top-like text ui
			- in a key -> value format
			- in an all keys, all values format

			The data is sampled from the KVM's debugfs entries and its perf events.
			"""

	import curses		import curses
	import sys		import sys
	@@ -217,8 +226,10 @@ IOCTL_NUMBERS = {
	}		}

	class Arch(object):		class Arch(object):
	"""Class that encapsulates global architecture specific data like		"""Encapsulates global architecture specific data.
	syscall and ioctl numbers.
			Contains the performance event open syscall and ioctl numbers, as
			well as the VM exit reasons for the architecture it runs on.

	"""		"""
	@staticmethod		@staticmethod
	@@ -306,12 +317,22 @@ def parse_int_list(list_string):


	def get_online_cpus():		def get_online_cpus():
			"""Returns a list of cpu id integers."""
	with open('/sys/devices/system/cpu/online') as cpu_list:		with open('/sys/devices/system/cpu/online') as cpu_list:
	cpu_string = cpu_list.readline()		cpu_string = cpu_list.readline()
	return parse_int_list(cpu_string)		return parse_int_list(cpu_string)


	def get_filters():		def get_filters():
			"""Returns a dict of trace events, their filter ids and
			the values that can be filtered.

			Trace events can be filtered for special values by setting a
			filter string via an ioctl. The string normally has the format
			identifier==value. For each filter a new event will be created, to
			be able to distinguish the events.

			"""
	filters = {}		filters = {}
	filters['kvm_userspace_exit'] = ('reason', USERSPACE_EXIT_REASONS)		filters['kvm_userspace_exit'] = ('reason', USERSPACE_EXIT_REASONS)
	if ARCH.exit_reasons:		if ARCH.exit_reasons:
	@@ -322,6 +343,14 @@ libc = ctypes.CDLL('libc.so.6', use_errno=True)
	syscall = libc.syscall		syscall = libc.syscall

	class perf_event_attr(ctypes.Structure):		class perf_event_attr(ctypes.Structure):
			"""Struct that holds the necessary data to set up a trace event.

			For an extensive explanation see perf_event_open(2) and
			include/uapi/linux/perf_event.h, struct perf_event_attr

			All fields that are not initialized in the constructor are 0.

			"""
	_fields_ = [('type', ctypes.c_uint32),		_fields_ = [('type', ctypes.c_uint32),
	('size', ctypes.c_uint32),		('size', ctypes.c_uint32),
	('config', ctypes.c_uint64),		('config', ctypes.c_uint64),
	@@ -342,6 +371,20 @@ class perf_event_attr(ctypes.Structure):
	self.read_format = PERF_FORMAT_GROUP		self.read_format = PERF_FORMAT_GROUP

	def perf_event_open(attr, pid, cpu, group_fd, flags):		def perf_event_open(attr, pid, cpu, group_fd, flags):
			"""Wrapper for the sys_perf_evt_open() syscall.

			Used to set up performance events, returns a file descriptor or -1
			on error.

			Attributes are:
			- syscall number
			- struct perf_event_attr *
			- pid or -1 to monitor all pids
			- cpu number or -1 to monitor all cpus
			- The file descriptor of the group leader or -1 to create a group.
			- flags

			"""
	return syscall(ARCH.sc_perf_evt_open, ctypes.pointer(attr),		return syscall(ARCH.sc_perf_evt_open, ctypes.pointer(attr),
	ctypes.c_int(pid), ctypes.c_int(cpu),		ctypes.c_int(pid), ctypes.c_int(cpu),
	ctypes.c_int(group_fd), ctypes.c_long(flags))		ctypes.c_int(group_fd), ctypes.c_long(flags))
	@@ -353,6 +396,8 @@ PATH_DEBUGFS_TRACING = '/sys/kernel/debug/tracing'
	PATH_DEBUGFS_KVM = '/sys/kernel/debug/kvm'		PATH_DEBUGFS_KVM = '/sys/kernel/debug/kvm'

	class Group(object):		class Group(object):
			"""Represents a perf event group."""

	def __init__(self):		def __init__(self):
	self.events = []		self.events = []

	@@ -360,6 +405,22 @@ class Group(object):
	self.events.append(event)		self.events.append(event)

	def read(self):		def read(self):
			"""Returns a dict with 'event name: value' for all events in the
			group.

			Values are read by reading from the file descriptor of the
			event that is the group leader. See perf_event_open(2) for
			details.

			Read format for the used event configuration is:
			struct read_format {
			u64 nr; /* The number of events */
			struct {
			u64 value; /* The value of the event */
			} values[nr];
			};

			"""
	length = 8 * (1 + len(self.events))		length = 8 * (1 + len(self.events))
	read_format = 'xxxxxxxx' + 'Q' * len(self.events)		read_format = 'xxxxxxxx' + 'Q' * len(self.events)
	return dict(zip([event.name for event in self.events],		return dict(zip([event.name for event in self.events],
	@@ -367,6 +428,7 @@ class Group(object):
	os.read(self.events[0].fd, length))))		os.read(self.events[0].fd, length))))

	class Event(object):		class Event(object):
			"""Represents a performance event and manages its life cycle."""
	def __init__(self, name, group, trace_cpu, trace_pid, trace_point,		def __init__(self, name, group, trace_cpu, trace_pid, trace_point,
	trace_filter, trace_set='kvm'):		trace_filter, trace_set='kvm'):
	self.name = name		self.name = name
	@@ -375,10 +437,19 @@ class Event(object):
	trace_filter, trace_set)		trace_filter, trace_set)

	def __del__(self):		def __del__(self):
			"""Closes the event's file descriptor.

			As no python file object was created for the file descriptor,
			python will not reference count the descriptor and will not
			close it itself automatically, so we do it.

			"""
	if self.fd:		if self.fd:
	os.close(self.fd)		os.close(self.fd)

	def setup_event_attribute(self, trace_set, trace_point):		def setup_event_attribute(self, trace_set, trace_point):
			"""Returns an initialized ctype perf_event_attr struct."""

	id_path = os.path.join(PATH_DEBUGFS_TRACING, 'events', trace_set,		id_path = os.path.join(PATH_DEBUGFS_TRACING, 'events', trace_set,
	trace_point, 'id')		trace_point, 'id')

	@@ -388,9 +459,19 @@ class Event(object):

	def setup_event(self, group, trace_cpu, trace_pid, trace_point,		def setup_event(self, group, trace_cpu, trace_pid, trace_point,
	trace_filter, trace_set):		trace_filter, trace_set):
			"""Sets up the perf event in Linux.

			Issues the syscall to register the event in the kernel and
			then sets the optional filter.

			"""

	event_attr = self.setup_event_attribute(trace_set, trace_point)		event_attr = self.setup_event_attribute(trace_set, trace_point)

			# First event will be group leader.
	group_leader = -1		group_leader = -1

			# All others have to pass the leader's descriptor instead.
	if group.events:		if group.events:
	group_leader = group.events[0].fd		group_leader = group.events[0].fd

	@@ -408,15 +489,33 @@ class Event(object):
	self.fd = fd		self.fd = fd

	def enable(self):		def enable(self):
			"""Enables the trace event in the kernel.

			Enabling the group leader makes reading counters from it and the
			events under it possible.

			"""
	fcntl.ioctl(self.fd, ARCH.ioctl_numbers['ENABLE'], 0)		fcntl.ioctl(self.fd, ARCH.ioctl_numbers['ENABLE'], 0)

	def disable(self):		def disable(self):
			"""Disables the trace event in the kernel.

			Disabling the group leader makes reading all counters under it
			impossible.

			"""
	fcntl.ioctl(self.fd, ARCH.ioctl_numbers['DISABLE'], 0)		fcntl.ioctl(self.fd, ARCH.ioctl_numbers['DISABLE'], 0)

	def reset(self):		def reset(self):
			"""Resets the count of the trace event in the kernel."""
	fcntl.ioctl(self.fd, ARCH.ioctl_numbers['RESET'], 0)		fcntl.ioctl(self.fd, ARCH.ioctl_numbers['RESET'], 0)

	class TracepointProvider(object):		class TracepointProvider(object):
			"""Data provider for the stats class.

			Manages the events/groups from which it acquires its data.

			"""
	def __init__(self):		def __init__(self):
	self.group_leaders = []		self.group_leaders = []
	self.filters = get_filters()		self.filters = get_filters()
	@@ -424,6 +523,20 @@ class TracepointProvider(object):
	self._pid = 0		self._pid = 0

	def get_available_fields(self):		def get_available_fields(self):
			"""Returns a list of available event's of format 'event name(filter
			name)'.

			All available events have directories under
			/sys/kernel/debug/tracing/events/ which export information
			about the specific event. Therefore, listing the dirs gives us
			a list of all available events.

			Some events like the vm exit reasons can be filtered for
			specific values. To take account for that, the routine below
			creates special fields with the following format:
			event name(filter name)

			"""
	path = os.path.join(PATH_DEBUGFS_TRACING, 'events', 'kvm')		path = os.path.join(PATH_DEBUGFS_TRACING, 'events', 'kvm')
	fields = walkdir(path)[1]		fields = walkdir(path)[1]
	extra = []		extra = []
	@@ -436,6 +549,8 @@ class TracepointProvider(object):
	return fields		return fields

	def setup_traces(self):		def setup_traces(self):
			"""Creates all event and group objects needed to be able to retrieve
			data."""
	if self._pid > 0:		if self._pid > 0:
	# Fetch list of all threads of the monitored pid, as qemu		# Fetch list of all threads of the monitored pid, as qemu
	# starts a thread for each vcpu.		# starts a thread for each vcpu.
	@@ -499,6 +614,7 @@ class TracepointProvider(object):

	@fields.setter		@fields.setter
	def fields(self, fields):		def fields(self, fields):
			"""Enables/disables the (un)wanted events"""
	self._fields = fields		self._fields = fields
	for group in self.group_leaders:		for group in self.group_leaders:
	for index, event in enumerate(group.events):		for index, event in enumerate(group.events):
	@@ -517,12 +633,16 @@ class TracepointProvider(object):

	@pid.setter		@pid.setter
	def pid(self, pid):		def pid(self, pid):
			"""Changes the monitored pid by setting new traces."""
	self._pid = pid		self._pid = pid
			# The garbage collector will get rid of all Event/Group
			# objects and open files after removing the references.
	self.group_leaders = []		self.group_leaders = []
	self.setup_traces()		self.setup_traces()
	self.fields = self._fields		self.fields = self._fields

	def read(self):		def read(self):
			"""Returns 'event name: current value' for all enabled events."""
	ret = defaultdict(int)		ret = defaultdict(int)
	for group in self.group_leaders:		for group in self.group_leaders:
	for name, val in group.read().iteritems():		for name, val in group.read().iteritems():
	@@ -531,12 +651,19 @@ class TracepointProvider(object):
	return ret		return ret

	class DebugfsProvider(object):		class DebugfsProvider(object):
			"""Provides data from the files that KVM creates in the kvm debugfs
			folder."""
	def __init__(self):		def __init__(self):
	self._fields = self.get_available_fields()		self._fields = self.get_available_fields()
	self._pid = 0		self._pid = 0
	self.do_read = True		self.do_read = True

	def get_available_fields(self):		def get_available_fields(self):
			""""Returns a list of available fields.

			The fields are all available KVM debugfs files

			"""
	return walkdir(PATH_DEBUGFS_KVM)[2]		return walkdir(PATH_DEBUGFS_KVM)[2]

	@property		@property
	@@ -592,6 +719,12 @@ class DebugfsProvider(object):
	return 0		return 0

	class Stats(object):		class Stats(object):
			"""Manages the data providers and the data they provide.

			It is used to set filters on the provider's data and collect all
			provider data.

			"""
	def __init__(self, providers, pid, fields=None):		def __init__(self, providers, pid, fields=None):
	self.providers = providers		self.providers = providers
	self._pid_filter = pid		self._pid_filter = pid
	@@ -601,6 +734,7 @@ class Stats(object):
	self.update_provider_filters()		self.update_provider_filters()

	def update_provider_filters(self):		def update_provider_filters(self):
			"""Propagates fields filters to providers."""
	def wanted(key):		def wanted(key):
	if not self._fields_filter:		if not self._fields_filter:
	return True		return True
	@@ -615,6 +749,7 @@ class Stats(object):
	provider.fields = provider_fields		provider.fields = provider_fields

	def update_provider_pid(self):		def update_provider_pid(self):
			"""Propagates pid filters to providers."""
	for provider in self.providers:		for provider in self.providers:
	provider.pid = self._pid_filter		provider.pid = self._pid_filter

	@@ -638,6 +773,8 @@ class Stats(object):
	self.update_provider_pid()		self.update_provider_pid()

	def get(self):		def get(self):
			"""Returns a dict with field -> (value, delta to last value) of all
			provider data."""
	for provider in self.providers:		for provider in self.providers:
	new = provider.read()		new = provider.read()
	for key in provider.fields:		for key in provider.fields:
	@@ -653,6 +790,7 @@ LABEL_WIDTH = 40
	NUMBER_WIDTH = 10		NUMBER_WIDTH = 10

	class Tui(object):		class Tui(object):
			"""Instruments curses to draw a nice text ui."""
	def __init__(self, stats):		def __init__(self, stats):
	self.stats = stats		self.stats = stats
	self.screen = None		self.screen = None
	@@ -687,6 +825,7 @@ class Tui(object):
	curses.endwin()		curses.endwin()

	def update_drilldown(self):		def update_drilldown(self):
			"""Sets or removes a filter that only allows fields without braces."""
	if not self.stats.fields_filter:		if not self.stats.fields_filter:
	self.stats.fields_filter = r'^[^\(]*$'		self.stats.fields_filter = r'^[^\(]*$'

	@@ -694,9 +833,11 @@ class Tui(object):
	self.stats.fields_filter = None		self.stats.fields_filter = None

	def update_pid(self, pid):		def update_pid(self, pid):
			"""Propagates pid selection to stats object."""
	self.stats.pid_filter = pid		self.stats.pid_filter = pid

	def refresh(self, sleeptime):		def refresh(self, sleeptime):
			"""Refreshes on-screen data."""
	self.screen.erase()		self.screen.erase()
	if self.stats.pid_filter > 0:		if self.stats.pid_filter > 0:
	self.screen.addstr(0, 0, 'kvm statistics - pid {0}'		self.screen.addstr(0, 0, 'kvm statistics - pid {0}'
	@@ -734,6 +875,11 @@ class Tui(object):
	self.screen.refresh()		self.screen.refresh()

	def show_filter_selection(self):		def show_filter_selection(self):
			"""Draws filter selection mask.

			Asks for a valid regex and sets the fields filter accordingly.

			"""
	while True:		while True:
	self.screen.erase()		self.screen.erase()
	self.screen.addstr(0, 0,		self.screen.addstr(0, 0,
	@@ -756,6 +902,11 @@ class Tui(object):
	continue		continue

	def show_vm_selection(self):		def show_vm_selection(self):
			"""Draws PID selection mask.

			Asks for a pid until a valid pid or 0 has been entered.

			"""
	while True:		while True:
	self.screen.erase()		self.screen.erase()
	self.screen.addstr(0, 0,		self.screen.addstr(0, 0,
	@@ -787,6 +938,7 @@ class Tui(object):
	continue		continue

	def show_stats(self):		def show_stats(self):
			"""Refreshes the screen and processes user input."""
	sleeptime = 0.25		sleeptime = 0.25
	while True:		while True:
	self.refresh(sleeptime)		self.refresh(sleeptime)
	@@ -809,6 +961,7 @@ class Tui(object):
	continue		continue

	def batch(stats):		def batch(stats):
			"""Prints statistics in a key, value format."""
	s = stats.get()		s = stats.get()
	time.sleep(1)		time.sleep(1)
	s = stats.get()		s = stats.get()
	@@ -817,6 +970,7 @@ def batch(stats):
	print '%-42s%10d%10d' % (key, values[0], values[1])		print '%-42s%10d%10d' % (key, values[0], values[1])

	def log(stats):		def log(stats):
			"""Prints statistics as reiterating key block, multiple value blocks."""
	keys = sorted(stats.get().iterkeys())		keys = sorted(stats.get().iterkeys())
	def banner():		def banner():
	for k in keys:		for k in keys:
	@@ -837,6 +991,7 @@ def log(stats):
	line += 1		line += 1

	def get_options():		def get_options():
			"""Returns processed program arguments."""
	description_text = """		description_text = """
	This script displays various statistics about VMs running under KVM.		This script displays various statistics about VMs running under KVM.
	The statistics are gathered from the KVM debugfs entries and / or the		The statistics are gathered from the KVM debugfs entries and / or the
	@@ -906,6 +1061,7 @@ Requirements:
	return options		return options

	def get_providers(options):		def get_providers(options):
			"""Returns a list of data providers depending on the passed options."""
	providers = []		providers = []

	if options.tracepoints:		if options.tracepoints:
	@@ -918,6 +1074,7 @@ def get_providers(options):
	return providers		return providers

	def check_access(options):		def check_access(options):
			"""Exits if the current user can't access all needed directories."""
	if not os.path.exists('/sys/kernel/debug'):		if not os.path.exists('/sys/kernel/debug'):
	sys.stderr.write('Please enable CONFIG_DEBUG_FS in your kernel.')		sys.stderr.write('Please enable CONFIG_DEBUG_FS in your kernel.')
	sys.exit(1)		sys.exit(1)

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