| # Copyright 2013 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| from metrics import Metric |
| |
| class CpuMetric(Metric): |
| """Calulates CPU load over a span of time.""" |
| |
| def __init__(self, browser): |
| super(CpuMetric, self).__init__() |
| self._results = None |
| self._browser = browser |
| self._start_cpu = None |
| |
| def DidStartBrowser(self, browser): |
| # Save the browser object so that cpu_stats can be accessed later. |
| self._browser = browser |
| |
| def Start(self, page, tab): |
| self._start_cpu = self._browser.cpu_stats |
| |
| def Stop(self, page, tab): |
| assert self._start_cpu, 'Must call Start() first' |
| self._results = _SubtractCpuStats(self._browser.cpu_stats, self._start_cpu) |
| |
| # Optional argument trace_name is not in base class Metric. |
| # pylint: disable=W0221 |
| def AddResults(self, tab, results, trace_name='cpu_utilization'): |
| assert self._results, 'Must call Stop() first' |
| # Add a result for each process type. |
| for process_type in self._results: |
| trace_name = '%s_%s' % (trace_name, process_type.lower()) |
| cpu_percent = 100 * self._results[process_type] |
| results.Add(trace_name, '%', cpu_percent, chart_name='cpu_utilization', |
| data_type='unimportant') |
| |
| |
| def _SubtractCpuStats(cpu_stats, start_cpu_stats): |
| """Computes average cpu usage over a time period for different process types. |
| |
| Each of the two cpu_stats arguments is a dict with the following format: |
| {'Browser': {'CpuProcessTime': ..., 'TotalTime': ...}, |
| 'Renderer': {'CpuProcessTime': ..., 'TotalTime': ...} |
| 'Gpu': {'CpuProcessTime': ..., 'TotalTime': ...}} |
| |
| The 'CpuProcessTime' fields represent the number of seconds of CPU time |
| spent in each process, and total time is the number of real seconds |
| that have passed (this may be a Unix timestamp). |
| |
| Returns: |
| A dict of process type names (Browser, Renderer, etc.) to ratios of cpu |
| time used to total time elapsed. |
| """ |
| cpu_usage = {} |
| for process_type in cpu_stats: |
| assert process_type in start_cpu_stats, 'Mismatching process types' |
| # Skip any process_types that are empty. |
| if (not cpu_stats[process_type]) or (not start_cpu_stats[process_type]): |
| continue |
| cpu_process_time = (cpu_stats[process_type]['CpuProcessTime'] - |
| start_cpu_stats[process_type]['CpuProcessTime']) |
| total_time = (cpu_stats[process_type]['TotalTime'] - |
| start_cpu_stats[process_type]['TotalTime']) |
| assert total_time > 0, 'Expected total_time > 0, was: %d' % total_time |
| cpu_usage[process_type] = float(cpu_process_time) / total_time |
| return cpu_usage |
| |