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# Copyright OpenEmbedded Contributors
# SPDX-License-Identifier: GPL-2.0-only
# Implements system state sampling. Called by buildstats.bbclass.
# Because it is a real Python module, it can hold persistent state,
# like open log files and the time of the last sampling.
import time
import re
import bb.event
class SystemStats:
def __init__(self, d):
bn = d.getVar('BUILDNAME')
bsdir = os.path.join(d.getVar('BUILDSTATS_BASE'), bn)
file_handlers = [('diskstats', self._reduce_diskstats),
('meminfo', self._reduce_meminfo),
('stat', self._reduce_stat)]
# Some hosts like openSUSE have readable /proc/pressure files
# but throw errors when these files are opened. Catch these error
# and ensure that the reduce_proc_pressure directory is not created.
if os.path.exists("/proc/pressure"):
with open('/proc/pressure/cpu', 'rb') as source:
pressuredir = os.path.join(bsdir, 'reduced_proc_pressure')
file_handlers.extend([('pressure/cpu', self._reduce_pressure),
('pressure/io', self._reduce_pressure),
('pressure/memory', self._reduce_pressure)])
except Exception:
self.proc_files = []
for filename, handler in (file_handlers):
# The corresponding /proc files might not exist on the host.
# For example, /proc/diskstats is not available in virtualized
# environments like Linux-VServer. Silently skip collecting
# the data.
if os.path.exists(os.path.join('/proc', filename)):
# In practice, this class gets instantiated only once in
# the bitbake cooker process. Therefore 'append' mode is
# not strictly necessary, but using it makes the class
# more robust should two processes ever write
# concurrently.
destfile = os.path.join(bsdir, '%sproc_%s.log' % ('reduced_' if handler else '', filename))
self.proc_files.append((filename, open(destfile, 'ab'), handler))
self.monitor_disk = open(os.path.join(bsdir, 'monitor_disk.log'), 'ab')
# Last time that we sampled /proc data resp. recorded disk monitoring data.
self.last_proc = 0
self.last_disk_monitor = 0
# Minimum number of seconds between recording a sample. This becames relevant when we get
# called very often while many short tasks get started. Sampling during quiet periods
# depends on the heartbeat event, which fires less often.
# By default, the Heartbeat events occur roughly once every second but the actual time
# between these events deviates by a few milliseconds, in most cases. Hence
# pick a somewhat arbitary tolerance such that we sample a large majority
# of the Heartbeat events. This ignores rare events that fall outside the minimum
# and may lead an extra sample in a given second every so often. However, it allows for fairly
# consistent intervals between samples without missing many events.
self.tolerance = 0.01
self.min_seconds = 1.0 - self.tolerance
self.meminfo_regex = re.compile(rb'^(MemTotal|MemFree|Buffers|Cached|SwapTotal|SwapFree):\s*(\d+)')
self.diskstats_regex = re.compile(rb'^([hsv]d.|mtdblock\d|mmcblk\d|cciss/c\d+d\d+.*)$')
self.diskstats_ltime = None
self.diskstats_data = None
self.stat_ltimes = None
# Last time we sampled /proc/pressure. All resources stored in a single dict with the key as filename
self.last_pressure = {"pressure/cpu": None, "pressure/io": None, "pressure/memory": None}
def close(self):
for _, output, _ in self.proc_files:
def _reduce_meminfo(self, time, data, filename):
Extracts 'MemTotal', 'MemFree', 'Buffers', 'Cached', 'SwapTotal', 'SwapFree'
and writes their values into a single line, in that order.
values = {}
for line in data.split(b'\n'):
m = self.meminfo_regex.match(line)
if m:
values[] =
if len(values) == 6:
return (time,
b' '.join([values[x] for x in
(b'MemTotal', b'MemFree', b'Buffers', b'Cached', b'SwapTotal', b'SwapFree')]) + b'\n')
def _diskstats_is_relevant_line(self, linetokens):
if len(linetokens) != 14:
return False
disk = linetokens[2]
return self.diskstats_regex.match(disk)
def _reduce_diskstats(self, time, data, filename):
relevant_tokens = filter(self._diskstats_is_relevant_line, map(lambda x: x.split(), data.split(b'\n')))
diskdata = [0] * 3
reduced = None
for tokens in relevant_tokens:
# rsect
diskdata[0] += int(tokens[5])
# wsect
diskdata[1] += int(tokens[9])
# use
diskdata[2] += int(tokens[12])
if self.diskstats_ltime:
# We need to compute information about the time interval
# since the last sampling and record the result as sample
# for that point in the past.
interval = time - self.diskstats_ltime
if interval > 0:
sums = [ a - b for a, b in zip(diskdata, self.diskstats_data) ]
readTput = sums[0] / 2.0 * 100.0 / interval
writeTput = sums[1] / 2.0 * 100.0 / interval
util = float( sums[2] ) / 10 / interval
util = max(0.0, min(1.0, util))
reduced = (self.diskstats_ltime, (readTput, writeTput, util))
self.diskstats_ltime = time
self.diskstats_data = diskdata
return reduced
def _reduce_nop(self, time, data, filename):
return (time, data)
def _reduce_stat(self, time, data, filename):
if not data:
return None
# CPU times {user, nice, system, idle, io_wait, irq, softirq} from first line
tokens = data.split(b'\n', 1)[0].split()
times = [ int(token) for token in tokens[1:] ]
reduced = None
if self.stat_ltimes:
user = float((times[0] + times[1]) - (self.stat_ltimes[0] + self.stat_ltimes[1]))
system = float((times[2] + times[5] + times[6]) - (self.stat_ltimes[2] + self.stat_ltimes[5] + self.stat_ltimes[6]))
idle = float(times[3] - self.stat_ltimes[3])
iowait = float(times[4] - self.stat_ltimes[4])
aSum = max(user + system + idle + iowait, 1)
reduced = (time, (user/aSum, system/aSum, iowait/aSum))
self.stat_ltimes = times
return reduced
def _reduce_pressure(self, time, data, filename):
Return reduced pressure: {avg10, avg60, avg300} and delta total compared to the previous sample
for the cpu, io and memory resources. A common function is used for all 3 resources since the
format of the /proc/pressure file is the same in each case.
if not data:
return None
tokens = data.split(b'\n', 1)[0].split()
avg10 = float(tokens[1].split(b'=')[1])
avg60 = float(tokens[2].split(b'=')[1])
avg300 = float(tokens[3].split(b'=')[1])
total = int(tokens[4].split(b'=')[1])
reduced = None
if self.last_pressure[filename]:
delta = total - self.last_pressure[filename]
reduced = (time, (avg10, avg60, avg300, delta))
self.last_pressure[filename] = total
return reduced
def sample(self, event, force):
Collect and log proc or disk_monitor stats periodically.
Return True if a new sample is collected and hence the value last_proc or last_disk_monitor
is changed.
retval = False
now = time.time()
if (now - self.last_proc > self.min_seconds) or force:
for filename, output, handler in self.proc_files:
with open(os.path.join('/proc', filename), 'rb') as input:
data =
if handler:
reduced = handler(now, data, filename)
reduced = (now, data)
if reduced:
if isinstance(reduced[1], bytes):
# Use as it is.
data = reduced[1]
# Convert to a single line.
data = (' '.join([str(x) for x in reduced[1]]) + '\n').encode('ascii')
# Unbuffered raw write, less overhead and useful
# in case that we end up with concurrent writes.
('%.0f\n' % reduced[0]).encode('ascii') +
data +
self.last_proc = now
retval = True
if isinstance(event, bb.event.MonitorDiskEvent) and \
((now - self.last_disk_monitor > self.min_seconds) or force):
('%.0f\n' % now).encode('ascii') +
''.join(['%s: %d\n' % (dev, sample.total_bytes - sample.free_bytes)
for dev, sample in event.disk_usage.items()]).encode('ascii') +
self.last_disk_monitor = now
retval = True
return retval