power-usage-report

#!/usr/bin/python

# (C) 2012 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 argparse
import sys
import os
import stat
import time
import re
import functools

# 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-1.13'], stdout=subprocess.PIPE) != 0:
        err += 'powertop-1.13 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)
    powertop = subprocess.Popen(['powertop-1.13', '-d', '-t', 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)

    fatrace = subprocess.Popen(['fatrace', '-tts', str(DURATION), 
        '-p', str(powertop.pid)], stdout=subprocess.PIPE, env=env)

    output = {}
    output['fatrace'] = fatrace.communicate()[0].decode('UTF-8', errors='ignore')
    output['powertop'] = powertop.communicate()[0].decode('UTF-8', errors='ignore')

    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
    prev_match = 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'''

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

    i = 0
    # skip headers until wakeups
    while i < len(lines) and not lines[i].startswith('Top causes for wakeups'):
        i += 1
    i += 1 # skip "top causes..." line

    print('====== Wakeups ======')
    while i < len(lines) and lines[i]:
        # skip "[Rescheduling interrupts] <kernel IPI>", it's distracting and
        # wanted
        if 'Rescheduling interrupts' not in lines[i]:
            print(lines[i])
        i += 1
    print('')

    while i < len(lines) and not lines[i]:
        i += 1

    print('====== Devices ======')
    skip_par = False
    while i < len(lines):
        # suggestions make more sense for interactive mode, skip
        if lines[i].startswith('Suggestion:'):
            skip_par = True

        # writes are already covered by fatrace
        if 'is writing to' in lines[i]:
            skip_par = True

        if skip_par:
            if not lines[i].strip():
                skip_par = False
        else:
            print(lines[i])

        i += 1

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()