1 /* 2 * Copyright 2016 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "ThermalManager.h" 9 10 #include "SkOSFile.h" 11 12 #include <stdio.h> 13 14 #ifndef SK_BUILD_FOR_WIN32 15 #include <unistd.h> 16 #endif 17 18 #ifdef THERMAL_MANAGER_SUPPORTED 19 20 /* 21 * ThermalManager is completely dependent on sysfs to monitor thermal temperatures. In sysfs 22 * thermal management is controlled by a number of thermal zones. They are laid out as follows: 23 * /sys/class/thermal/thermal_zoneN where N is the number of the thermal zone starting at 0. 24 * 25 * Inside each thermal_zone folder is a file called 'temp,' which has the current temperature 26 * reading from the sensor in that zone, as well as 0 or more files called 'trip_point_N_temp.' 27 * 28 * When the reading in temp is greater than one of the numbers in the trip_point files, then the 29 * kernel will take some kind of action. This is all documented online. 30 * 31 * In any case, the goal of this class is to sleep right before a trip point is about to be 32 * triggered, thus naturally cooling the system and preventing thermal throttling. 33 */ 34 35 ThermalManager::ThermalManager(int32_t threshold, uint32_t sleepIntervalMs, uint32_t timeoutMs) 36 : fSleepIntervalMs(sleepIntervalMs) 37 , fTimeoutMs(timeoutMs) { 38 static const char* kThermalZonePath = "/sys/class/thermal/"; 39 SkOSFile::Iter it(kThermalZonePath); 40 SkString path; 41 while (it.next(&path, true)) { 42 if (!path.contains("thermal_zone")) { 43 continue; 44 } 45 46 SkString fullPath(kThermalZonePath); 47 fullPath.append(path); 48 SkOSFile::Iter thermalZoneIt(fullPath.c_str()); 49 50 SkString filename; 51 while (thermalZoneIt.next(&filename)) { 52 if (!(filename.contains("trip_point") && filename.contains("temp"))) { 53 continue; 54 } 55 56 fTripPoints.push_back(TripPoint(fullPath, filename, threshold)); 57 } 58 } 59 } 60 61 bool ThermalManager::coolOffIfNecessary() { 62 uint32_t i = 0, totalTimeSleptMs = 0; 63 while (i < (uint32_t)fTripPoints.count() && totalTimeSleptMs < fTimeoutMs) { 64 if (fTripPoints[i].willTrip()) { 65 sleep(fSleepIntervalMs); 66 totalTimeSleptMs += fSleepIntervalMs; 67 } else { 68 i++; 69 } 70 } 71 72 return totalTimeSleptMs < fTimeoutMs; 73 } 74 75 int32_t ThermalManager::OpenFileAndReadInt32(const char* path) { 76 FILE* tempFile = fopen(path, "r"); 77 SkASSERT(tempFile); 78 int32_t value; 79 int ret = fscanf(tempFile, "%d", &value); 80 if (!ret) { 81 SkDebugf("Could not read temperature\n"); 82 SkASSERT(false); 83 } 84 85 fclose(tempFile); 86 return value; 87 } 88 89 ThermalManager::TripPoint::TripPoint(SkString thermalZoneRoot, SkString pointName, 90 int32_t threshold) 91 : fThermalZoneRoot(thermalZoneRoot) 92 , fPointName(pointName) { 93 SkString fullPath(thermalZoneRoot); 94 fullPath.appendf("/%s", pointName.c_str()); 95 fPoint = OpenFileAndReadInt32(fullPath.c_str()); 96 fBase = GetTemp(fThermalZoneRoot); 97 fThreshold = threshold; 98 fDisabled = fBase + fThreshold >= fPoint; // We disable any trip point which start off 99 // triggered 100 } 101 102 bool ThermalManager::TripPoint::willTrip() { 103 int32_t currentTemp = GetTemp(fThermalZoneRoot); 104 bool wouldTrip = !fDisabled && currentTemp + fThreshold >= fPoint; 105 106 if (wouldTrip) { 107 SkDebugf("%s/%s would trip {%d,%d,%d,%d}\n", fThermalZoneRoot.c_str(), 108 fPointName.c_str(), fBase, currentTemp, fPoint, fThreshold); 109 } 110 return wouldTrip; 111 } 112 113 #endif 114