Raphael | 0384a98 | 2009-09-15 17:10:17 -0700 | [diff] [blame] | 1 | |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 2 | /* libs/cutils/sched_policy.c |
| 3 | ** |
| 4 | ** Copyright 2007, The Android Open Source Project |
| 5 | ** |
| 6 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | ** you may not use this file except in compliance with the License. |
| 8 | ** You may obtain a copy of the License at |
| 9 | ** |
| 10 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | ** |
| 12 | ** Unless required by applicable law or agreed to in writing, software |
| 13 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | ** See the License for the specific language governing permissions and |
| 16 | ** limitations under the License. |
| 17 | */ |
| 18 | |
| 19 | #include <stdio.h> |
| 20 | #include <stdlib.h> |
| 21 | #include <unistd.h> |
| 22 | #include <string.h> |
| 23 | #include <errno.h> |
| 24 | #include <fcntl.h> |
Raphael | 0384a98 | 2009-09-15 17:10:17 -0700 | [diff] [blame] | 25 | |
San Mehat | d2e4e46 | 2009-10-29 11:48:00 -0700 | [diff] [blame^] | 26 | #define LOG_TAG "SchedPolicy" |
| 27 | #include "cutils/log.h" |
| 28 | |
Raphael | 0384a98 | 2009-09-15 17:10:17 -0700 | [diff] [blame] | 29 | #ifdef HAVE_SCHED_H |
| 30 | |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 31 | #include <sched.h> |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 32 | |
| 33 | #include <cutils/sched_policy.h> |
| 34 | |
San Mehat | 3cd5b66 | 2009-09-14 16:05:24 -0700 | [diff] [blame] | 35 | #ifndef SCHED_NORMAL |
| 36 | #define SCHED_NORMAL 0 |
| 37 | #endif |
| 38 | |
| 39 | #ifndef SCHED_BATCH |
| 40 | #define SCHED_BATCH 3 |
| 41 | #endif |
| 42 | |
San Mehat | d2e4e46 | 2009-10-29 11:48:00 -0700 | [diff] [blame^] | 43 | #define POLICY_DEBUG 1 |
| 44 | |
San Mehat | c0dfca7 | 2009-10-27 11:52:55 -0700 | [diff] [blame] | 45 | static int __sys_supports_schedgroups = -1; |
| 46 | |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 47 | static int add_tid_to_cgroup(int tid, const char *grp_name) |
| 48 | { |
| 49 | int fd; |
| 50 | char path[255]; |
| 51 | char text[64]; |
| 52 | |
| 53 | sprintf(path, "/dev/cpuctl/%s/tasks", grp_name); |
| 54 | |
| 55 | if ((fd = open(path, O_WRONLY)) < 0) |
| 56 | return -1; |
| 57 | |
| 58 | sprintf(text, "%d", tid); |
| 59 | if (write(fd, text, strlen(text)) < 0) { |
| 60 | close(fd); |
| 61 | return -1; |
| 62 | } |
| 63 | |
| 64 | close(fd); |
| 65 | return 0; |
| 66 | } |
| 67 | |
San Mehat | c0dfca7 | 2009-10-27 11:52:55 -0700 | [diff] [blame] | 68 | static inline void initialize() |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 69 | { |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 70 | if (__sys_supports_schedgroups < 0) { |
| 71 | if (!access("/dev/cpuctl/tasks", F_OK)) { |
| 72 | __sys_supports_schedgroups = 1; |
| 73 | } else { |
| 74 | __sys_supports_schedgroups = 0; |
| 75 | } |
| 76 | } |
San Mehat | c0dfca7 | 2009-10-27 11:52:55 -0700 | [diff] [blame] | 77 | } |
| 78 | |
| 79 | /* |
| 80 | * Try to get the scheduler group. |
| 81 | * |
| 82 | * The data from /proc/<pid>/cgroup looks like: |
| 83 | * 2:cpu:/bg_non_interactive |
| 84 | * |
| 85 | * We return the part after the "/", which will be an empty string for |
| 86 | * the default cgroup. If the string is longer than "bufLen", the string |
| 87 | * will be truncated. |
| 88 | */ |
| 89 | static int getSchedulerGroup(int tid, char* buf, size_t bufLen) |
| 90 | { |
| 91 | #ifdef HAVE_ANDROID_OS |
| 92 | char pathBuf[32]; |
| 93 | char readBuf[256]; |
| 94 | ssize_t count; |
| 95 | int fd; |
| 96 | |
| 97 | snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid); |
| 98 | if ((fd = open(pathBuf, O_RDONLY)) < 0) { |
| 99 | return -1; |
| 100 | } |
| 101 | |
| 102 | count = read(fd, readBuf, sizeof(readBuf)); |
| 103 | if (count <= 0) { |
| 104 | close(fd); |
| 105 | errno = ENODATA; |
| 106 | return -1; |
| 107 | } |
| 108 | close(fd); |
| 109 | |
| 110 | readBuf[--count] = '\0'; /* remove the '\n', now count==strlen */ |
| 111 | |
| 112 | char* cp = strchr(readBuf, '/'); |
| 113 | if (cp == NULL) { |
| 114 | readBuf[sizeof(readBuf)-1] = '\0'; |
| 115 | errno = ENODATA; |
| 116 | return -1; |
| 117 | } |
| 118 | |
| 119 | memcpy(buf, cp+1, count); /* count-1 for cp+1, count+1 for NUL */ |
| 120 | return 0; |
| 121 | #else |
| 122 | errno = ENOSYS; |
| 123 | return -1; |
| 124 | #endif |
| 125 | } |
| 126 | |
| 127 | int get_sched_policy(int tid, SchedPolicy *policy) |
| 128 | { |
| 129 | initialize(); |
| 130 | |
| 131 | if (__sys_supports_schedgroups) { |
| 132 | char grpBuf[32]; |
| 133 | if (getSchedulerGroup(tid, grpBuf, sizeof(grpBuf)) < 0) |
| 134 | return -1; |
| 135 | if (grpBuf[0] == '\0') { |
| 136 | *policy = SP_FOREGROUND; |
| 137 | } else if (!strcmp(grpBuf, "bg_non_interactive")) { |
| 138 | *policy = SP_BACKGROUND; |
| 139 | } else { |
| 140 | errno = ERANGE; |
| 141 | return -1; |
| 142 | } |
| 143 | } else { |
| 144 | int rc = sched_getscheduler(tid); |
| 145 | if (rc < 0) |
| 146 | return -1; |
| 147 | else if (rc == SCHED_NORMAL) |
| 148 | *policy = SP_FOREGROUND; |
| 149 | else if (rc == SCHED_BATCH) |
| 150 | *policy = SP_BACKGROUND; |
| 151 | else { |
| 152 | errno = ERANGE; |
| 153 | return -1; |
| 154 | } |
| 155 | } |
| 156 | return 0; |
| 157 | } |
| 158 | |
| 159 | int set_sched_policy(int tid, SchedPolicy policy) |
| 160 | { |
| 161 | initialize(); |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 162 | |
San Mehat | d2e4e46 | 2009-10-29 11:48:00 -0700 | [diff] [blame^] | 163 | #if POLICY_DEBUG |
| 164 | char statfile[64]; |
| 165 | char statline[1024]; |
| 166 | char thread_name[255]; |
| 167 | int fd; |
| 168 | |
| 169 | sprintf(statfile, "/proc/%d/stat", tid); |
| 170 | memset(thread_name, 0, sizeof(thread_name)); |
| 171 | |
| 172 | fd = open(statfile, O_RDONLY); |
| 173 | if (fd >= 0) { |
| 174 | int rc = read(fd, statline, 1023); |
| 175 | close(fd); |
| 176 | statline[rc] = 0; |
| 177 | char *p = statline; |
| 178 | char *q; |
| 179 | |
| 180 | for (p = statline; *p != '('; p++); |
| 181 | p++; |
| 182 | for (q = p; *q != ')'; q++); |
| 183 | |
| 184 | strncpy(thread_name, p, (q-p)); |
| 185 | } |
| 186 | if (policy == SP_BACKGROUND) { |
| 187 | LOGD("vvv tid %d (%s)", tid, thread_name); |
| 188 | } else if (policy == SP_FOREGROUND) { |
| 189 | LOGD("^^^ tid %d (%s)", tid, thread_name); |
| 190 | } else { |
| 191 | LOGD("??? tid %d (%s)", tid, thread_name); |
| 192 | } |
| 193 | #endif |
| 194 | |
San Mehat | 493dad9 | 2009-09-12 10:06:57 -0700 | [diff] [blame] | 195 | if (__sys_supports_schedgroups) { |
| 196 | const char *grp = NULL; |
| 197 | |
| 198 | if (policy == SP_BACKGROUND) { |
| 199 | grp = "bg_non_interactive"; |
| 200 | } |
| 201 | |
| 202 | if (add_tid_to_cgroup(tid, grp)) { |
| 203 | if (errno != ESRCH && errno != ENOENT) |
| 204 | return -errno; |
| 205 | } |
| 206 | } else { |
| 207 | struct sched_param param; |
| 208 | |
| 209 | param.sched_priority = 0; |
| 210 | sched_setscheduler(tid, |
| 211 | (policy == SP_BACKGROUND) ? |
| 212 | SCHED_BATCH : SCHED_NORMAL, |
| 213 | ¶m); |
| 214 | } |
| 215 | |
| 216 | return 0; |
| 217 | } |
Raphael | 0384a98 | 2009-09-15 17:10:17 -0700 | [diff] [blame] | 218 | |
| 219 | #endif /* HAVE_SCHED_H */ |