/usr/sbin/hwlatdetect is in rt-tests 0.87-1ubuntu1.
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# (C) 2009 Clark Williams <williams@redhat.com>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License Version 2
# as published by the Free Software Foundation.
import sys
import os
import time
import subprocess
import errno
version = "0.6"
debugging = False
quiet = False
def debug(str):
if debugging: print(str)
def info(str):
if not quiet: print(str)
#
# Class used to manage mounting and umounting the debugfs
# filesystem. Note that if an instance of this class mounts
# the debufs, it will unmount when cleaning up, but if it
# discovers that debugfs is already mounted, it will leave
# it mounted.
#
class DebugFS(object):
'''class to manage mounting/umounting the debugfs'''
def __init__(self):
self.premounted = False
self.mounted = False
self.mountpoint = ''
f = open('/proc/mounts')
for l in f:
field = l.split()
if field[2] == "debugfs":
self.premounted = True
self.mountpoint = field[1]
break
f.close()
def mount(self, path='/sys/kernel/debug'):
if self.premounted or self.mounted:
debug("not mounting debugfs")
return True
debug("mounting debugfs at %s" % path)
self.mountpoint = path
cmd = ['/bin/mount', '-t', 'debugfs', 'none', path]
self.mounted = (subprocess.call(cmd) == 0)
if not self.mounted:
raise RuntimeError, "Failed to mount debugfs"
return self.mounted
def umount(self):
if self.premounted or not self.mounted:
debug("not umounting debugfs")
return True
debug("umounting debugfs")
cmd = ['/bin/umount', self.mountpoint]
self.mounted = not (subprocess.call(cmd) == 0)
if self.mounted:
raise RuntimeError, "Failed to umount debugfs"
return not self.mounted
def getval(self, item, nonblocking=False):
path = os.path.join(self.mountpoint, item)
if nonblocking == False:
f = open(path)
val = f.readline()
f.close()
else:
fd = os.open(path, os.O_RDONLY|os.O_NONBLOCK)
try:
val = os.read(fd, 256)
except OSError, e:
if e.errno == errno.EAGAIN:
val = None
else:
raise
os.close(fd)
return val
def putval(self, item, value):
path = os.path.join(self.mountpoint, item)
f = open(path, "w")
f.write(str(value))
f.flush()
f.close()
def getpath(self, item):
return os.path.join(self.mountpoint, item)
#
# Class used to manage loading and unloading of the
# hwlat kernel module. Like the debugfs class
# above, if the module is already loaded, this class will
# leave it alone when cleaning up.
#
class Kmod(object):
''' class to manage loading and unloading hwlat.ko'''
names = ("hwlat_detector", "smi_detector")
def __find_modname(self):
debug("looking for modules")
path = os.path.join("/lib/modules",
os.uname()[2],
"kernel/drivers/misc")
debug("module path: %s" % path)
for m in Kmod.names:
mpath = os.path.join(path, m) + ".ko"
debug("checking %s" % mpath)
if os.path.exists(mpath):
return m
raise RuntimeError, "no detector module found!"
def __init__(self):
self.preloaded = False
f = open ('/proc/modules')
for l in f:
field = l.split()
if field[0] in Kmod.names:
self.preloaded = True
self.modname = field[0]
debug("using already loaded %s" % self.modname)
f.close()
break
f.close()
self.modname = self.__find_modname()
def load(self):
if self.preloaded:
debug("not loading %s (already loaded)" % self.modname)
return True
cmd = ['/sbin/modprobe', self.modname]
return (subprocess.call(cmd) == 0)
def unload(self):
if self.preloaded:
debug("Not unloading %s" % self.modname)
return True
cmd = ['/sbin/modprobe', '-r', self.modname]
return (subprocess.call(cmd) == 0)
#
# wrapper class for detection modules
#
class Detector(object):
'''wrapper class for managing detector modules'''
def __init__(self):
if os.getuid() != 0:
raise RuntimeError, "Must be root"
self.debugfs = DebugFS()
self.kmod = Kmod()
self.setup()
if self.kmod.modname == "hwlat_detector":
self.detector = Hwlat(self.debugfs)
elif self.kmod.modname == "smi_detector":
self.detector = Smi(self.debugfs)
self.samples = []
self.testduration = 10 # ten seconds
def force_cleanup(self):
debug("forcing unload of hwlat module")
self.kmod.preloaded = False
debug("forcing unmount of debugfs")
self.debugfs.premounted = False
self.cleanup()
debug("exiting")
sys.exit(0)
def setup(self):
if not self.debugfs.mount():
raise RuntimeError, "Failed to mount debugfs"
if not self.kmod.load():
raise RuntimeError, "Failed to unload hwlat"
def cleanup(self):
if not self.kmod.unload():
raise RuntimeError, "Failed to unload hwlat"
if not self.debugfs.umount():
raise RuntimeError, "Failed to unmount debugfs"
def get(self, field):
return self.detector.get(field)
def set(self, field, val):
return self.detector.set(field, val)
def start(self):
count = 0
threshold = self.get("threshold")
debug("enabling detector module (threshold: %d)" % threshold)
self.detector.set("enable", 1)
debug("first attempt at enable")
while self.detector.get("enable") == 0:
debug("still disabled, retrying in a bit")
count += 1
time.sleep(0.1)
debug("retrying enable of detector module (%d)" % count)
self.detector.set("enable", 1)
if self.get("threshold") != threshold:
debug("start: threshold reset by start, fixing")
self.set("threshold", threshold)
debug("detector module enabled (threshold: %d)" % self.get("threshold"))
def stop(self):
count = 0
debug("disabling detector module")
self.detector.set("enable", 0)
debug("first attempt at disable");
while self.detector.get("enable") == 1:
debug("still enabled, retrying in a bit")
count += 1
time.sleep(0.1)
debug("retrying disable of detector module(%d)" % count)
self.detector.set("enable", 0)
debug("detector module disabled")
def detect(self):
debug("Starting hardware latency detection for %d seconds" % self.testduration)
self.start()
try:
self.samples = self.detector.detect(self.testduration)
finally:
self.stop()
debug("Hardware latency detection done (%d samples)" % len(self.samples))
#
# Class to simplify running the hwlat kernel module
#
class Hwlat(object):
'''class to wrap access to hwlat debugfs files'''
def __init__(self, debugfs):
self.debugfs = debugfs
def get(self, field):
return int(self.debugfs.getval(os.path.join("hwlat_detector", field)))
def set(self, field, val):
if field == "enable" and val:
val = 1
self.debugfs.putval(os.path.join("hwlat_detector", field), str(val))
def get_sample(self):
return self.debugfs.getval("hwlat_detector/sample", nonblocking=True)
def detect(self, duration):
self.samples = []
testend = time.time() + duration
pollcnt = 0
try:
while time.time() < testend:
pollcnt += 1
val = self.get_sample()
while val:
self.samples.append(val.strip())
debug("got a latency sample: %s" % val.strip())
val = self.get_sample()
time.sleep(0.1)
except KeyboardInterrupt, e:
print "interrupted"
sys.exit(1)
return self.samples
#
# the old smi_detector.ko module has different debugfs entries than the modern
# hwlat_detector.ko module; this object translates the current entries into the
# old style ones. The only real issue is that the smi_detector module doesn't
# have the notion of width/window, it has the sample time and the interval
# between samples. Of course window == sample time + interval, but you have to
# have them both to calculate the window.
#
class Smi(object):
'''class to wrap access to smi_detector debugfs files'''
field_translate = {
"count" : "smi_count",
"enable" : "enable",
"max" : "max_sample_us",
"sample" : "sample_us",
"threshold" : "latency_threshold_us",
"width" : "ms_per_sample",
"window" : "ms_between_sample",
}
def __init__(self, debugfs):
self.width = 0
self.window = 0
self.debugfs = debugfs
def __get(self, field):
return int(self.debugfs.getval(os.path.join("smi_detector", field)))
def __set(self, field, value):
debug("__set: %s <-- %d" % (field, value))
self.debugfs.putval(os.path.join("smi_detector", field), str(value))
if self.__get(field) != value:
raise RuntimeError, "Error setting %s to %d (%d)" % (field, value, self.__get(field))
def get(self, field):
name = Smi.field_translate[field]
if name != field:
debug("get: %s translated to %s" % (field, name))
if field == "window":
return self.get_window()
elif field == "width":
return ms2us(self.__get(name))
else:
return self.__get(name)
def get_window(self):
sample = ms2us(self.__get('ms_per_sample'))
interval = ms2us(self.__get('ms_between_samples'))
return sample + interval
def set_window(self, window):
width = ms2us(int(self.__get('ms_per_sample')))
interval = window - width
if interval <= 0:
raise RuntimeError, "Smi: invalid width/interval values (%d/%d (%d))" % (width, interval, window)
self.__set('ms_between_samples', us2ms(interval))
def set(self, field, val):
name = Smi.field_translate[field]
if name != field:
debug ("set: %s translated to %s" % (field, name))
if field == "enable" and val:
val = 1
if field == "window":
self.set_window(val)
else:
if field == "width":
val = us2ms(val)
self.__set(name, val)
def get_sample(self):
name = Smi.field_translate["sample"]
return self.debugfs.getval(os.path.join('smi_detector', name), nonblocking=True)
def detect(self, duration):
self.samples = []
testend = time.time() + duration
threshold = self.get("threshold")
debug("detect: threshold %d" % threshold)
pollcnt = 0
try:
while time.time() < testend:
pollcnt += 1
val = self.get_sample()
if int(val) >= threshold:
self.samples.append(val.strip())
debug("got a latency sample: %s (threshold: %d)" % (val.strip(), self.get("threshold")))
time.sleep(0.1)
except KeyboardInterrupt, e:
print "interrupted"
sys.exit(1)
return self.samples
def ms2us(val):
return val * 1000
def us2ms(val):
return val / 1000
def seconds(str):
"convert input string to value in seconds"
if str.isdigit():
return int(str)
elif str[-2].isalpha():
raise RuntimeError, "illegal suffix for seconds: '%s'" % str[-2:-1]
elif str[-1:] == 's':
return int(str[0:-1])
elif str[-1:] == 'm':
return int(str[0:-1]) * 60
elif str[-1:] == 'h':
return int(str[0:-1]) * 3600
elif str[-1:] == 'd':
return int(str[0:-1]) * 86400
elif str[-1:] == 'w':
return int(str[0:-1]) * 86400 * 7
else:
raise RuntimeError, "invalid input for seconds: '%s'" % str
def milliseconds(str):
"convert input string to millsecond value"
if str.isdigit():
return int(str)
elif str[-2:] == 'ms':
return int(str[0:-2])
elif str[-1] == 's':
return int(str[0:-2]) * 1000
elif str[-1] == 'm':
return int(str[0:-1]) * 1000 * 60
elif str[-1] == 'h':
return int(str[0:-1]) * 1000 * 60 * 60
else:
raise RuntimeError, "invalid input for milliseconds: %s" % str
def microseconds(str):
"convert input string to microsecond value"
if str.isdigit():
return int(str)
elif str[-2:] == 'ms':
return (int(str[0:-2]) * 1000)
elif str[-2:] == 'us':
return int(str[0:-2])
elif str[-1:] == 's':
return (int(str[0:-1]) * 1000 * 1000)
else:
raise RuntimeError, "invalid input for microseconds: '%s'" % str
if __name__ == '__main__':
from optparse import OptionParser
parser = OptionParser()
parser.add_option("--duration", default=None, type="string",
dest="duration",
help="total time to test for hardware latency (<n>{smdw})")
parser.add_option("--threshold", default=None, type="string",
dest="threshold",
help="value above which is considered an hardware latency")
parser.add_option("--window", default=None, type="string",
dest="window",
help="time between samples")
parser.add_option("--width", default=None, type="string",
dest="width",
help="time to actually measure")
parser.add_option("--report", default=None, type="string",
dest="report",
help="filename for sample data")
parser.add_option("--cleanup", action="store_true", default=False,
dest="cleanup",
help="force unload of module and umount of debugfs")
parser.add_option("--debug", action="store_true", default=False,
dest="debug",
help="turn on debugging prints")
parser.add_option("--quiet", action="store_true", default=False,
dest="quiet",
help="turn off all screen output")
(o, a) = parser.parse_args()
# need these before creating detector instance
if o.debug:
debugging = True
quiet = False
debug("debugging prints turned on")
if o.quiet:
quiet = True
debugging = False
detect = Detector()
if o.cleanup:
debug("forcing cleanup of debugfs and hardware latency module")
detect.force_cleanup()
sys.exit(0)
if o.threshold:
t = microseconds(o.threshold)
detect.set("threshold", t)
debug("threshold set to %dus" % t)
if o.window:
w = microseconds(o.window)
if w < detect.get("width"):
debug("shrinking width to %d for new window of %d" % (w/2, w))
detect.set("width", w/2)
debug("window parameter = %d" % w)
detect.set("window", w)
debug("window for sampling set to %dus" % w)
if o.width:
w = microseconds(o.width)
if w > detect.get("window"):
debug("widening window to %d for new width of %d" % (w*2, w))
detect.set("window", w*2)
debug("width parameter = %d" % w)
detect.set("width", w)
debug("sample width set to %dus" % w)
if o.duration:
detect.testduration = seconds(o.duration)
else:
detect.testduration = 120 # 2 minutes
debug("test duration is %ds" % detect.testduration)
reportfile = o.report
info("hwlatdetect: test duration %d seconds" % detect.testduration)
info(" parameters:")
info(" Latency threshold: %dus" % detect.get("threshold"))
info(" Sample window: %dus" % detect.get("window"))
info(" Sample width: %dus" % detect.get("width"))
info(" Non-sampling period: %dus" % (detect.get("window") - detect.get("width")))
info(" Output File: %s" % reportfile)
info("\nStarting test")
detect.detect()
info("test finished")
exceeding = detect.get("count")
info("Max Latency: %dus" % detect.get("max"))
info("Samples recorded: %d" % len(detect.samples))
info("Samples exceeding threshold: %d" % exceeding)
if reportfile:
count = 0
f = open(reportfile, "w")
for s in detect.samples:
count += 1
f.write("%s\n" % s)
f.close()
info("sample data (%d samples) written to %s" % (count, reportfile))
else:
for s in detect.samples:
print "%s" % s
detect.cleanup()
sys.exit(exceeding)
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