1 # Copyright 2015 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 """Facade to access the system-related functionality.""" 6 7 import os 8 9 from autotest_lib.client.bin import utils 10 11 12 class SystemFacadeNativeError(Exception): 13 """Error in SystemFacadeNative.""" 14 pass 15 16 17 class SystemFacadeNative(object): 18 """Facede to access the system-related functionality. 19 20 The methods inside this class only accept Python native types. 21 22 """ 23 SCALING_GOVERNOR_MODES = [ 24 'interactive', 25 'performance', 26 'ondemand', 27 'powersave', 28 ] 29 30 def set_scaling_governor_mode(self, index, mode): 31 """Set mode of CPU scaling governor on one CPU. 32 33 @param index: CPU index starting from 0. 34 35 @param mode: Mode of scaling governor, accept 'interactive' or 36 'performance'. 37 38 @returns: The original mode. 39 40 """ 41 if mode not in self.SCALING_GOVERNOR_MODES: 42 raise SystemFacadeNativeError('mode %s is invalid' % mode) 43 44 governor_path = os.path.join( 45 '/sys/devices/system/cpu/cpu%d' % index, 46 'cpufreq/scaling_governor') 47 if not os.path.exists(governor_path): 48 raise SystemFacadeNativeError( 49 'scaling governor of CPU %d is not available' % index) 50 51 original_mode = utils.read_one_line(governor_path) 52 utils.open_write_close(governor_path, mode) 53 54 return original_mode 55
