power-usage-report

#!/usr/bin/python3

# (C) 2012, 2013 Canonical Ltd.
# Author: Martin Pitt <martin.pitt@ubuntu.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import subprocess
import sys
import os
import time
import re
import functools
import tempfile

# standard time for measuring in seconds
DURATION = 60


def check_dependencies():
    '''Check if necessary programs are installed and privileges are available.'''

    err = ''

    if os.geteuid() != 0:
        err += 'You need to run this program as root.\n\n'

    if subprocess.call(['which', 'powertop'], stdout=subprocess.PIPE) != 0:
        err += 'powertop not found, please install it.\n\n'

    if err:
        sys.stderr.write(err)
        sys.exit(1)


def probe():
    '''Call probes and return their output in a dict.'''

    # ensure that programs run without translations, to avoid breaking parsing
    env = os.environ.copy()
    env['LC_MESSAGES'] = 'C'

    sys.stderr.write('Starting measurement for %i seconds...\n' % DURATION)
    (fd, powertop_csv) = tempfile.mkstemp(suffix='.csv', prefix='powertop')
    os.close(fd)
    powertop = subprocess.Popen(['powertop', '--csv=' + powertop_csv,
                                 '--time=' + str(DURATION + 1)],
                                stdout=subprocess.PIPE, env=env)
    # let powertop initialize; calls lspci and some shell scripts which skew
    # the fatrace results
    time.sleep(1)

    output = {}
    fatrace = subprocess.Popen(['fatrace', '-tts', str(DURATION), '-p', str(powertop.pid)],
                               stdout=subprocess.PIPE, env=env)
    output['fatrace'] = fatrace.communicate()[0].decode('UTF-8', errors='ignore')

    powertop.communicate()
    with open(powertop_csv, 'rb') as f:
        output['powertop'] = f.read().decode('UTF-8', errors='ignore')
    os.unlink(powertop_csv)

    return output


def parse_fatrace_events(lines):
    '''Parse fatrace output lines.

    Split lines into fields, filter out bursts of identical events (usually
    from reading/writing larger blocks).

    Return array of (program, pid, mode, file) tuples.
    '''
    event_re = re.compile('(\d+.\d+) (\S+)\((\d+)\): ([A-Z]+) (.+)$')

    prev_timestamp = None

    events = []

    for line in lines:
        m = event_re.match(line)
        if not m:
            sys.stderr.write('Ignoring unparseable line: %s\n' % line)
            continue

        timestamp = float(m.group(1))
        event = m.groups()[1:]
        if prev_timestamp and (timestamp - prev_timestamp < 0.01) and event == events[-1]:
            continue
        prev_timestamp = timestamp

        events.append(event)

    return events


def group_fatrace_events(events):
    '''Group fatrace events.

    Return dict program -> file > [#reads,#writes]
    '''
    groups = {}
    for event in events:
        if event[2] == 'C':
            # ignore read-close events for now
            continue

        stat = groups.setdefault(event[0], {}).setdefault(event[3], [0, 0])
        if 'W' in event[2]:
            stat[1] += 1
        elif event[2] in ('R', 'O', 'RO'):
            stat[0] += 1

    return groups


def fatrace_report(raw_out):
    '''Generate disk access report from raw fatrace output'''

    lines = raw_out.splitlines()
    event_lines = parse_fatrace_events(lines)
    events = group_fatrace_events(event_lines)

    # sort programs by number of events
    events_per_prog = []
    for prog, filemap in events.items():
        count = functools.reduce(lambda sum, rw: sum + rw[0] + rw[1], filemap.values(), 0)
        events_per_prog.append((prog, count))
    events_per_prog.sort(key=lambda i: i[1], reverse=True)

    for (prog, count) in events_per_prog:
        print('======= %s: %i file access events ======' % (prog, count))
        for file, (r, w) in events[prog].items():
            s = file + ':'
            if r > 0:
                s += ' %i reads' % r
            if w > 0:
                s += ' %i writes' % w
            print(s)
        print('')


def powertop_report(raw_out):
    '''Generate report from raw powertop output'''

    # map powertop's headers to our headers for interesting parts
    blocks = [
        ('overview of software power consumers', 'Wakeups'),
        ('device power report', 'Devices'),
        ('process device activity', 'Process Device Activity'),
    ]

    # filter out multiple empty lines
    lines = re.sub('\n{3,}', '\n\n', raw_out).splitlines()
    i = 0

    for (search_header, print_header) in blocks:
        # skip until search_header
        while i < len(lines) and not search_header in lines[i].lower():
            i += 1
        i += 1  # skip header
        # skip empty lines
        while not lines[i]:
            i += 1

        print('====== %s ======' % print_header)
        while i < len(lines) and lines[i] and not lines[i].startswith('_____'):
            print(lines[i])
            i += 1
        print('')


def main():
    check_dependencies()

    # Announce that we are about to start
    sys.stderr.write('''Measurement will begin in 5 seconds. Please make sure that the
computer is idle, i. e. do not press keys, start or operate programs, and that
programs are not busy with active tasks other than the one you want to examine.\n''')
    time.sleep(5)

    output = probe()

    sys.stderr.write('Measurement complete. Generating report...\n')
    fatrace_report(output['fatrace'])
    powertop_report(output['powertop'])

if __name__ == '__main__':
    main()