| # Copyright 2015 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """Facade to access the system-related functionality.""" |
| |
| import os |
| |
| from autotest_lib.client.bin import utils |
| |
| |
| class SystemFacadeNativeError(Exception): |
| """Error in SystemFacadeNative.""" |
| pass |
| |
| |
| class SystemFacadeNative(object): |
| """Facede to access the system-related functionality. |
| |
| The methods inside this class only accept Python native types. |
| |
| """ |
| SCALING_GOVERNOR_MODES = [ |
| 'interactive', |
| 'performance', |
| 'ondemand', |
| 'powersave', |
| ] |
| |
| def set_scaling_governor_mode(self, index, mode): |
| """Set mode of CPU scaling governor on one CPU. |
| |
| @param index: CPU index starting from 0. |
| |
| @param mode: Mode of scaling governor, accept 'interactive' or |
| 'performance'. |
| |
| @returns: The original mode. |
| |
| """ |
| if mode not in self.SCALING_GOVERNOR_MODES: |
| raise SystemFacadeNativeError('mode %s is invalid' % mode) |
| |
| governor_path = os.path.join( |
| '/sys/devices/system/cpu/cpu%d' % index, |
| 'cpufreq/scaling_governor') |
| if not os.path.exists(governor_path): |
| raise SystemFacadeNativeError( |
| 'scaling governor of CPU %d is not available' % index) |
| |
| original_mode = utils.read_one_line(governor_path) |
| utils.open_write_close(governor_path, mode) |
| |
| return original_mode |
