# HG changeset patch
# User Daniel Stodden <daniel.stodden@xxxxxxxxxx>
# Date 1308667132 -3600
# Node ID bff008a26377798a168d71a87b73f5eb7a1ea3ec
# Parent b17fbeed15488dfa789d8cff0eca6a5808479a41
tools: xen-ringwatch: spot, and work around, broken frontend/backend ring I/O
Adds tool support to debug backends which expose I/O ring state in
sysfs. Currently supports /sys/devices/xen-backend/vbd-*-*/io_ring
nodes for block I/O, where implemented.
Primary function is to observe ring state make progress over a period
of time, then report stuck message queue halves where pending
consumer/event are not moving.
Adding --kick will re-issue event notifications to frontends, and/or
kick backends out of wait state.
Signed-off-by: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
diff -r b17fbeed1548 -r bff008a26377 tools/misc/Makefile
--- a/tools/misc/Makefile Tue Jun 21 15:31:34 2011 +0100
+++ b/tools/misc/Makefile Tue Jun 21 15:38:52 2011 +0100
@@ -21,7 +21,7 @@
INSTALL_BIN-$(CONFIG_X86) += xen-detect
INSTALL_BIN := $(INSTALL_BIN-y)
-INSTALL_SBIN-y := xm xen-bugtool xen-python-path xend xenperf xsview xenpm
xen-tmem-list-parse gtraceview gtracestat xenlockprof xenwatchdogd
+INSTALL_SBIN-y := xm xen-bugtool xen-python-path xend xenperf xsview xenpm
xen-tmem-list-parse gtraceview gtracestat xenlockprof xenwatchdogd xen-ringwatch
INSTALL_SBIN-$(CONFIG_X86) += xen-hvmctx xen-hvmcrash
INSTALL_SBIN-$(CONFIG_MIGRATE) += xen-hptool
INSTALL_SBIN := $(INSTALL_SBIN-y)
diff -r b17fbeed1548 -r bff008a26377 tools/misc/xen-ringwatch
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/misc/xen-ringwatch Tue Jun 21 15:38:52 2011 +0100
@@ -0,0 +1,619 @@
+#!/usr/bin/python
+#
+# Copyright (C) 2011 Citrix Systems, Inc.
+#
+# This library is free software; you can redistribute it and/or modify
+# it under the terms of version 2.1 of the GNU Lesser General Public
+# License as published by the Free Software Foundation.
+#
+# This library is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+# USA
+#
+
+"""Overview:
+
+ - Gather Xen I/O ring states
+ (from %s/*/ring)
+
+ - Update ring states every -T seconds.
+
+ - Determine if rings are idle or make progress.
+
+ - Determine if idle rings dropped notifications (%s).
+
+ - Instruct stuck backends to reissue notifications.
+"""
+
+import os
+import glob
+
+class Pattern(object):
+ """A regex pattern. Compiled on demand, then persisted."""
+
+ def __init__(self, regex):
+ self.regex = regex
+ self.__pattern = None
+
+ def get(self):
+ import re
+
+ if not self.__pattern:
+ self.__pattern = re.compile(self.regex)
+
+ return self.__pattern
+
+ def search(self, s):
+ return self.get().search(s)
+
+class XenBackend(object):
+ """A Xen I/O backend."""
+
+ SYSFS_BASEDIR = "/sys/devices/xen-backend"
+
+ def __init__(self, rd, devid):
+ self.rd = int(rd)
+ self.devid = int(devid)
+
+ def __repr__(self):
+ return "%s(%d, %d)" % (type(self).__name__,
+ self.rd, self.devid)
+
+ def name(self):
+ raise NotImplementedError
+
+ def path(self):
+ return "%s/%s" % (self.SYSFS_BASEDIR, self.name())
+
+ _name_pattern = None
+
+ @classmethod
+ def from_name(cls, name):
+ match = cls._name_pattern.search(name)
+ if not match:
+ raise Exception, "Malformed %s name: %s" % \
+ (type(self).__name__, name)
+
+ rd = match.group(1)
+ devid = match.group(2)
+
+ return cls(rd, devid)
+
+ _name_glob = None
+
+ @classmethod
+ def find(cls):
+ paths = glob.glob("%s/%s" % (cls.SYSFS_BASEDIR,
+ cls._name_glob))
+ for path in paths:
+ name = os.path.basename(path)
+ yield cls.from_name(name)
+
+ def find_rings(self):
+ for ring in self.Ring.find(self):
+ yield ring
+
+ class Ring(object):
+
+ def __init__(self, backend, name):
+ self.backend = backend
+ self.name = name
+
+ __size = None
+
+ def key(self):
+ return "%s/%s" % (self.backend.name(),
+ self.name)
+
+ def __str__(self):
+ return "%s(%s)" % (type(self).__name__, self.key())
+
+ @classmethod
+ def from_name(cls, backend, name):
+ return cls(backend, name)
+
+ _name_glob = None
+
+ @classmethod
+ def find(cls, backend):
+ paths = glob.glob("%s/%s" % (backend.path(),
+ cls._name_glob))
+ for path in paths:
+ name = os.path.basename(path)
+ yield cls.from_name(backend, name)
+
+ def path(self):
+ return "%s/%s" % (self.backend.path(),
+ self.name)
+
+ def read(self):
+ state = RingState.from_sysfs(self.path())
+ return state
+
+ def write(self, cmd):
+ f = file(self.path(), 'w')
+ try:
+ f.write(cmd.rstrip())
+ finally:
+ f.close()
+
+ def kick(self):
+ self.write("kick")
+
+ def poll(self):
+ self.write("poll")
+
+ __ring = None
+
+ TYPES = {}
+ XEN_BACKEND_NAME = None
+
+ @classmethod
+ def register(cls):
+ XenBackend.TYPES[cls.XEN_BACKEND_NAME] = cls
+
+class VBD(XenBackend):
+ """Xen blkif backends."""
+
+ XEN_BACKEND_NAME = 'vbd'
+
+ _name_pattern = Pattern("vbd-(\d+)-(\d+)")
+ _name_glob = "vbd-*-*"
+
+ def name(self):
+ return "vbd-%d-%d" % (self.rd, self.devid)
+
+ class Ring(XenBackend.Ring):
+ _name_glob = "io_ring"
+
+VBD.register()
+
+class VIF(XenBackend):
+ """Xen netif backends."""
+
+ XEN_BACKEND_NAME = 'vif'
+
+ _name_pattern = Pattern("vif-(\d+)-(\d+)")
+ _name_glob = "vif-*-*"
+
+ def name(self):
+ return "vif-%d-%d" % (self.rd, self.devid)
+
+ class Ring(XenBackend.Ring):
+ _name_glob = "{rx,tx}_ring"
+
+#VIF.register()
+
+class RingState(object):
+ """Overall backend ring state. Comprising req and rsp queue
+ indexes, and analysis."""
+
+ def __init__(self, size, req, rsp):
+ self.size = int(size)
+ self.req = req
+ self.rsp = rsp
+
+ _size_pattern = Pattern("nr_ents (\d+)")
+
+ @classmethod
+ def from_sysfs(cls, path):
+
+ f = file(path, "r")
+ try:
+ s = f.read()
+ finally:
+ f.close()
+
+ try:
+ (_nr_ents, _req, _rsp, _) = s.split("\n")
+
+ match = cls._size_pattern.search(_nr_ents)
+ nr_ents = int(match.group(1))
+
+ except Exception, e:
+ raise Exception, "Malformed %s input: %s (%s)" % \
+ (cls.__name__, repr(s), str(e))
+
+ req = cls.Req.from_sysfs(_req, size=nr_ents)
+ rsp = cls.Rsp.from_sysfs(_rsp, size=nr_ents)
+
+ return cls(nr_ents, req, rsp)
+
+ class Queue(dict):
+
+ def __init__(self, size):
+ self.size = int(size)
+
+ prod = None
+
+ @classmethod
+ def from_sysfs(cls, line, **d):
+
+ match = cls._pattern.search(line)
+ if not match:
+ raise Exception, "Malformed %s input: %s" % \
+ (cls.__name__, repr(s))
+
+ i = iter(match.groups())
+ for k in i:
+ d[k] = i.next()
+
+ return cls(**d)
+
+ def is_consumed(self):
+ return self.prod == self._cons()
+
+ class Req(Queue):
+
+ _pattern = Pattern("req (prod) (\d+) (cons) (\d+) (event) (\d+)")
+
+ def __init__(self, prod, cons, event, **d):
+ RingState.Queue.__init__(self, **d)
+ self.prod = int(prod)
+ self.cons = int(cons)
+ self.event = int(event)
+
+ def __repr__(self):
+ return "%s(prod=%d, cons=%d, event=%d)" % \
+ (type(self).__name__, self.prod, self.cons, self.event)
+
+ def _cons(self):
+ return self.cons
+
+ def __eq__(self, other):
+ return \
+ self.prod == other.prod and \
+ self.cons == other.cons and \
+ self.event == other.event
+
+ class Rsp(Queue):
+
+ _pattern = Pattern("rsp (prod) (\d+) (pvt) (\d+) (event) (\d+)")
+
+ def __init__(self, prod, pvt, event, **d):
+ RingState.Queue.__init__(self, **d)
+ self.prod = int(prod)
+ self.pvt = int(pvt)
+ self.event = int(event)
+
+ def __repr__(self):
+ return "%s(prod=%d, pvt=%d, event=%d)" % \
+ (type(self).__name__, self.prod, self.pvt, self.event)
+
+ def _cons(self):
+ return self.event - 1
+
+ def __eq__(self, other):
+ return \
+ self.prod == other.prod and \
+ self.pvt == other.pvt and \
+ self.event == other.event
+
+ def is_consumed(self):
+ return \
+ self.rsp.is_consumed() and \
+ self.req.is_consumed()
+
+ def is_pending(self):
+ return self.rsp.prod != self.req.prod
+
+ def kick(self, ring):
+ action = False
+
+ if not self.req.is_consumed():
+ action |= True
+ ring.poll()
+
+ if not self.rsp.is_consumed():
+ action |= True
+ ring.kick()
+
+ return action
+
+ def __eq__(self, other):
+ return \
+ self.size == other.size and \
+ self.req == other.req and \
+ self.rsp == other.rsp
+
+ def __repr__(self):
+ return "%s(size=%d, %s, %s)" % \
+ (type(self).__name__, self.size, self.req, self.rsp)
+
+ def display(self):
+ complete = { True: "complete", False: "pending" }
+
+ io = complete[not self.is_pending()]
+ req = complete[self.req.is_consumed()]
+ rsp = complete[self.rsp.is_consumed()]
+
+ return "%s: io: %s, req: %s, rsp: %s" % (self, io, req, rsp)
+
+class RingWatch(object):
+ """State machine watching I/O individual ring state"""
+
+ _NEW = "_NEW"
+ BUSY = "BUSY"
+ IDLE = "IDLE"
+ STCK = "STCK"
+
+ COMMENTS = { BUSY: "Message traffic observed (OK)",
+ IDLE: "No messages observed (Ring OK, I/O depends)",
+ STCK: "No pending req/rsp consumer progress observed (BUG)" }
+
+ def __init__(self, ring, state):
+ self.ring = ring
+ self.state = state
+ self.status = RingWatch._NEW
+
+ @classmethod
+ def new(cls, ring):
+ state = ring.read()
+ return cls(ring, state)
+
+ def __str__(self):
+ return "%s(%s)[%s]" % \
+ (type(self).__name__, self.ring.key(), self.status)
+
+ def is_stuck(self):
+ return self.status == self.STCK
+
+ def is_idle(self):
+ return self.status == self.IDLE
+
+ def kick(self):
+ if self.is_stuck():
+ return self.state.kick(self.ring)
+
+ def update(self):
+
+ prev = self.state
+ curr = self.ring.read()
+
+ if curr == prev:
+ if not curr.is_consumed():
+ self.status = self.STCK
+ else:
+ self.status = self.IDLE
+ else:
+ self.status = self.BUSY
+
+ self.state = curr
+
+ def display(self):
+ return "%s: %s" % (self,
+ self.state.display())
+
+class WatchList(object):
+ """Managed collection of I/O rings under surveillance."""
+
+ def __init__(self, gen):
+ self.gen = gen
+ self.list = {}
+
+ def update(self):
+
+ # NB. clear the watch list, then rebuild it. new entries get
+ # added, existing ones updates, those gone discarded.
+ prev = self.list
+ self.list = {}
+
+ for ring in self.gen():
+
+ key = ring.key()
+ entry = prev.get(key)
+
+ try:
+ if not entry:
+ entry = RingWatch.new(ring)
+ else:
+ entry.update()
+
+ except IOError, e:
+ pass
+ # NB. racing unplug, any ring.read() may raise.
+ # nothing left to memorize then.
+ else:
+ self.list[key] = entry
+
+ def __iter__(self):
+ return self.list.itervalues()
+
+ def pending(self):
+ for entry in self:
+ if entry.is_idle() and entry.state.is_pending():
+ yield entry
+
+ def stuck(self):
+ for entry in self:
+ if entry.is_stuck():
+ yield entry
+
+ def kick(self):
+ for entry in self.stuck():
+ try:
+ entry.kick()
+ except IOError:
+ # NB. racing unplug, any ring.write() may raise.
+ pass
+
+if __name__ == '__main__':
+ from sys import argv, stdout, stderr, exit
+ from getopt import gnu_getopt, GetoptError
+ from pprint import pprint
+
+ DEFAULT_PERIOD = 1 # secs
+
+ verbose = 0
+ period = DEFAULT_PERIOD
+ backends = XenBackend.TYPES.values()
+ kick = False
+ iowatch = False
+
+ OPTIONS = ((('h', 'help'),
+ "Print this help screen."),
+
+ (('v', 'verbose'),
+ "Increase output verbosity level (use n-times)."),
+
+ (('I', 'io'),
+ "Watch out for stuck I/O (not messaging), too. (%s)" % \
+ (iowatch)),
+
+ (('t', 'types'),
+ "Comma separated list of backend types to watch. (%s)" % \
+ ",".join(map(lambda t: t.XEN_BACKEND_NAME, backends))),
+
+ (('T', 'period'),
+ "Watch update period. (%d) [secs]" % \
+ (period)),
+
+ (('k', 'kick'),
+ "Kick broken guests out of cardiac arrest. (%s)" % \
+ (kick))
+ )
+
+ COMMANDS = {"check":
+ "Single iteration quick test (takes -T seconds)."}
+
+ def usage(stream):
+ prog = os.path.basename(argv[0])
+
+ print >>stream
+
+ print >>stream, "Usage:"
+ print >>stream, "\t%s [options] {%s}" % (prog, "|".join(COMMANDS))
+
+ print >>stream
+
+ print >>stream, "Commands:"
+ for (name, desc) in COMMANDS.iteritems():
+ print >>stream, "\t%s: \t%s" % (name, desc)
+
+ print >>stream
+
+ print >>stream, "Options:"
+ for ((short, _long), desc) in OPTIONS:
+ print >>stream, "\t-%s, --%s: \t%s" % (short, _long, desc)
+
+ print >>stream
+
+ def fail(msg = None):
+ if msg: print >>stderr, "Error: %s" % msg
+ usage(stderr)
+ exit(1)
+
+ def help():
+
+ usage(stdout)
+
+ print __doc__ % (XenBackend.SYSFS_BASEDIR, RingWatch.STCK)
+
+ print "Backend Types:"
+ for k, v in XenBackend.TYPES.iteritems():
+ print "\t%s: \t%s (%s)" % (k, v.__doc__, v._name_glob)
+
+ print
+ print "Ring States:"
+ for k, v in RingWatch.COMMENTS.iteritems():
+ print "\t%s: \t%s" % (k, v)
+
+ print
+
+ try:
+ opts, args = gnu_getopt(argv[1:],
+ "hIkt:vT:",
+ ["help",
+ "io",
+ "kick",
+ "type=",
+ "verbose",
+ "period="])
+ except GetoptError, e:
+ fail(str(e))
+
+ for (o, arg) in opts:
+ try:
+ if o in ('-h', '--help'):
+ help()
+ exit(0)
+
+ elif o in ['-v', '--verbose']:
+ verbose += 1
+
+ elif o in ['-I', '--io']:
+ iowatch = True
+
+ elif o in ('-T', '--period'):
+ period = int(arg)
+
+ elif o in ('-t', '--type'):
+ backends = ",".split(arg)
+ backends = map(lambda t: XenBackend.TYPES[t], backends)
+
+ elif o in ('-k', '--kick'):
+ kick = True
+
+ else:
+ raise "BUG: option %s unhandled." % o
+
+ except ValueError:
+ fail("%s: invalid argument '%s'." % (o, arg))
+
+ try:
+ cmd = args[0]
+ except IndexError:
+ fail("Missing command.")
+
+ def ring_select():
+ for _type in backends:
+ for backend in _type.find():
+ for ring in backend.find_rings():
+ yield ring
+
+ def show(entries):
+ for watch in entries:
+ print watch.display()
+
+ def pause():
+ import time
+ time.sleep(period)
+
+ watches = WatchList(ring_select)
+
+ if cmd == "check":
+
+ # init
+ watches.update()
+
+ if verbose >= 2:
+ show(watches)
+
+ # watch for one round
+ pause()
+ watches.update()
+
+ # show result
+ crit = list(watches.stuck())
+ stuck = bool(crit)
+
+ if (iowatch):
+ crit.extend(watches.pending())
+
+ if verbose >= 1:
+ show(watches)
+ elif crit:
+ show(crit)
+
+ if stuck and kick:
+ # deal with it
+ watches.kick()
+
+ else:
+ fail("Invalid command.")
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