instruments: add proc_stat

Add an instrument that monitors CPU load using data from /proc/stat

wa/instruments/proc_stat/__init__.py

@@ -0,0 +1,94 @@
+#    Copyright 2020 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+import os
+import time
+from datetime import datetime, timedelta
+
+import pandas as pd
+
+from wa import Instrument, Parameter, File, InstrumentError
+
+
+class ProcStatCollector(Instrument):
+
+    name = 'proc_stat'
+    description = '''
+    Collect CPU load information from /proc/stat.
+    '''
+
+    parameters = [
+        Parameter('period', int, default=5,
+                  constraint=lambda x: x > 0,
+                  description='''
+                  Time (in seconds) between collections.
+                  '''),
+    ]
+
+    def initialize(self, context):  # pylint: disable=unused-argument
+        self.host_script = context.get_resource(File(self, 'gather-load.sh'))
+        self.target_script = self.target.install(self.host_script)
+        self.target_output = self.target.get_workpath('proc-stat-raw.csv')
+        self.stop_file = self.target.get_workpath('proc-stat-stop.signal')
+
+    def setup(self, context):  # pylint: disable=unused-argument
+        self.command = '{} sh {} {} {} {} {}'.format(
+            self.target.busybox,
+            self.target_script,
+            self.target.busybox,
+            self.target_output,
+            self.period,
+            self.stop_file,
+        )
+        self.target.remove(self.target_output)
+        self.target.remove(self.stop_file)
+
+    def start(self, context):  # pylint: disable=unused-argument
+        self.target.kick_off(self.command)
+
+    def stop(self, context):  # pylint: disable=unused-argument
+        self.target.execute('{} touch {}'.format(self.target.busybox, self.stop_file))
+
+    def update_output(self, context):
+        self.logger.debug('Waiting for collector script to terminate...')
+        self._wait_for_script()
+        self.logger.debug('Waiting for collector script to terminate...')
+        host_output = os.path.join(context.output_directory, 'proc-stat-raw.csv')
+        self.target.pull(self.target_output, host_output)
+        context.add_artifact('proc-stat-raw', host_output, kind='raw')
+
+        df = pd.read_csv(host_output)
+        no_ts = df[df.columns[1:]]
+        deltas = (no_ts - no_ts.shift())
+        total = deltas.sum(axis=1)
+        util = (total - deltas.idle) / total * 100
+        out_df = pd.concat([df.timestamp, util], axis=1).dropna()
+        out_df.columns = ['timestamp', 'cpu_util']
+
+        util_file = os.path.join(context.output_directory, 'proc-stat.csv')
+        out_df.to_csv(util_file, index=False)
+        context.add_artifact('proc-stat', util_file, kind='data')
+
+    def finalize(self, context):  # pylint: disable=unused-argument
+        if self.cleanup_assets and getattr(self, 'target_output'):
+            self.target.remove(self.target_output)
+            self.target.remove(self.target_script)
+
+    def _wait_for_script(self):
+        start_time = datetime.utcnow()
+        timeout = timedelta(seconds=300)
+        while self.target.file_exists(self.stop_file):
+            delta = datetime.utcnow() - start_time
+            if delta > timeout:
+                raise InstrumentError('Timed out wating for /proc/stat collector to terminate..')

wa/instruments/proc_stat/gather-load.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+BUSYBOX=$1
+OUTFILE=$2
+PERIOD=$3
+STOP_SIGNAL_FILE=$4
+
+if [ "$#" != "4" ]; then
+    echo "USAGE: gather-load.sh BUSYBOX OUTFILE PERIOD STOP_SIGNAL_FILE"
+    exit 1
+fi
+
+echo "timestamp,user,nice,system,idle,iowait,irq,softirq,steal,guest,guest_nice" > $OUTFILE
+while true; do
+    echo -n $(${BUSYBOX} date -Iseconds) >> $OUTFILE
+    ${BUSYBOX} cat /proc/stat | ${BUSYBOX} head -n 1 | \
+        ${BUSYBOX} cut -d ' ' -f 2- | ${BUSYBOX} sed 's/ /,/g' >> $OUTFILE
+    if [ -f $STOP_SIGNAL_FILE ]; then
+        rm $STOP_SIGNAL_FILE
+        break
+    else
+        sleep $PERIOD
+    fi
+done