libcutils/sched_policy.c - android-core - Git at Google


 /* libs/cutils/sched_policy.c
 **
 ** Copyright 2007, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

 #define LOG_TAG "SchedPolicy"

 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <cutils/sched_policy.h>
 #include <cutils/log.h>

 /* Re-map SP_DEFAULT to the system default policy, and leave other values unchanged.
  * Call this any place a SchedPolicy is used as an input parameter.
  * Returns the possibly re-mapped policy.
  */
 static inline SchedPolicy _policy(SchedPolicy p)
 {
    return p == SP_DEFAULT ? SP_SYSTEM_DEFAULT : p;
 }

 #if defined(HAVE_ANDROID_OS) && defined(HAVE_SCHED_H) && defined(HAVE_PTHREADS)

 #include <sched.h>
 #include <pthread.h>

 #ifndef SCHED_NORMAL
   #define SCHED_NORMAL 0
 #endif

 #ifndef SCHED_BATCH
   #define SCHED_BATCH 3
 #endif

 #define POLICY_DEBUG 0

 #define CAN_SET_SP_SYSTEM 0 // non-zero means to implement set_sched_policy(tid, SP_SYSTEM)

 static pthread_once_t the_once = PTHREAD_ONCE_INIT;

 static int __sys_supports_schedgroups = -1;

 // File descriptors open to /dev/cpuctl/../tasks, setup by initialize, or -1 on error.
 static int bg_cgroup_fd = -1;
 static int fg_cgroup_fd = -1;
 #if CAN_SET_SP_SYSTEM
 static int system_cgroup_fd = -1;
 #endif

 /* Add tid to the scheduling group defined by the policy */
 static int add_tid_to_cgroup(int tid, SchedPolicy policy)
 {
     int fd;

     switch (policy) {
     case SP_BACKGROUND:
         fd = bg_cgroup_fd;
         break;
     case SP_FOREGROUND:
     case SP_AUDIO_APP:
     case SP_AUDIO_SYS:
         fd = fg_cgroup_fd;
         break;
 #if CAN_SET_SP_SYSTEM
     case SP_SYSTEM:
         fd = system_cgroup_fd;
         break;
 #endif
     default:
         fd = -1;
         break;
     }

     if (fd < 0) {
         SLOGE("add_tid_to_cgroup failed; policy=%d\n", policy);
         return -1;
     }

     // specialized itoa -- works for tid > 0
     char text[22];
     char *end = text + sizeof(text) - 1;
     char *ptr = end;
     *ptr = '\0';
     while (tid > 0) {
         *--ptr = '0' + (tid % 10);
         tid = tid / 10;
     }

     if (write(fd, ptr, end - ptr) < 0) {
         /*
          * If the thread is in the process of exiting,
          * don't flag an error
          */
         if (errno == ESRCH)
                 return 0;
         SLOGW("add_tid_to_cgroup failed to write '%s' (%s); policy=%d\n",
               ptr, strerror(errno), policy);
         return -1;
     }

     return 0;
 }

 static void __initialize(void) {
     char* filename;
     if (!access("/dev/cpuctl/tasks", F_OK)) {
         __sys_supports_schedgroups = 1;

 #if CAN_SET_SP_SYSTEM
         filename = "/dev/cpuctl/tasks";
         system_cgroup_fd = open(filename, O_WRONLY | O_CLOEXEC);
         if (system_cgroup_fd < 0) {
             SLOGV("open of %s failed: %s\n", filename, strerror(errno));
         }
 #endif

         filename = "/dev/cpuctl/apps/tasks";
         fg_cgroup_fd = open(filename, O_WRONLY | O_CLOEXEC);
         if (fg_cgroup_fd < 0) {
             SLOGE("open of %s failed: %s\n", filename, strerror(errno));
         }

         filename = "/dev/cpuctl/apps/bg_non_interactive/tasks";
         bg_cgroup_fd = open(filename, O_WRONLY | O_CLOEXEC);
         if (bg_cgroup_fd < 0) {
             SLOGE("open of %s failed: %s\n", filename, strerror(errno));
         }
     } else {
         __sys_supports_schedgroups = 0;
     }
 }

 /*
  * Try to get the scheduler group.
  *
  * The data from /proc/<pid>/cgroup looks (something) like:
  *  2:cpu:/bg_non_interactive
  *  1:cpuacct:/
  *
  * We return the part after the "/", which will be an empty string for
  * the default cgroup.  If the string is longer than "bufLen", the string
  * will be truncated.
  */
 static int getSchedulerGroup(int tid, char* buf, size_t bufLen)
 {
 #ifdef HAVE_ANDROID_OS
     char pathBuf[32];
     char lineBuf[256];
     FILE *fp;

     snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
     if (!(fp = fopen(pathBuf, "r"))) {
         return -1;
     }

     while(fgets(lineBuf, sizeof(lineBuf) -1, fp)) {
         char *next = lineBuf;
         char *subsys;
         char *grp;
         size_t len;

         /* Junk the first field */
         if (!strsep(&next, ":")) {
             goto out_bad_data;
         }

         if (!(subsys = strsep(&next, ":"))) {
             goto out_bad_data;
         }

         if (strcmp(subsys, "cpu")) {
             /* Not the subsys we're looking for */
             continue;
         }

         if (!(grp = strsep(&next, ":"))) {
             goto out_bad_data;
         }
         grp++; /* Drop the leading '/' */
         len = strlen(grp);
         grp[len-1] = '\0'; /* Drop the trailing '\n' */

         if (bufLen <= len) {
             len = bufLen - 1;
         }
         strncpy(buf, grp, len);
         buf[len] = '\0';
         fclose(fp);
         return 0;
     }

     SLOGE("Failed to find cpu subsys");
     fclose(fp);
     return -1;
  out_bad_data:
     SLOGE("Bad cgroup data {%s}", lineBuf);
     fclose(fp);
     return -1;
 #else
     errno = ENOSYS;
     return -1;
 #endif
 }

 int get_sched_policy(int tid, SchedPolicy *policy)
 {
 #ifdef HAVE_GETTID
     if (tid == 0) {
         tid = gettid();
     }
 #endif
     pthread_once(&the_once, __initialize);

     if (__sys_supports_schedgroups) {
         char grpBuf[32];
         if (getSchedulerGroup(tid, grpBuf, sizeof(grpBuf)) < 0)
             return -1;
         if (grpBuf[0] == '\0') {
             *policy = SP_SYSTEM;
         } else if (!strcmp(grpBuf, "apps/bg_non_interactive")) {
             *policy = SP_BACKGROUND;
         } else if (!strcmp(grpBuf, "apps")) {
             *policy = SP_FOREGROUND;
         } else {
             errno = ERANGE;
             return -1;
         }
     } else {
         int rc = sched_getscheduler(tid);
         if (rc < 0)
             return -1;
         else if (rc == SCHED_NORMAL)
             *policy = SP_FOREGROUND;
         else if (rc == SCHED_BATCH)
             *policy = SP_BACKGROUND;
         else {
             errno = ERANGE;
             return -1;
         }
     }
     return 0;
 }

 int set_sched_policy(int tid, SchedPolicy policy)
 {
 #ifdef HAVE_GETTID
     if (tid == 0) {
         tid = gettid();
     }
 #endif
     policy = _policy(policy);
     pthread_once(&the_once, __initialize);

 #if POLICY_DEBUG
     char statfile[64];
     char statline[1024];
     char thread_name[255];
     int fd;

     sprintf(statfile, "/proc/%d/stat", tid);
     memset(thread_name, 0, sizeof(thread_name));

     fd = open(statfile, O_RDONLY);
     if (fd >= 0) {
         int rc = read(fd, statline, 1023);
         close(fd);
         statline[rc] = 0;
         char *p = statline;
         char *q;

         for (p = statline; *p != '('; p++);
         p++;
         for (q = p; *q != ')'; q++);

         strncpy(thread_name, p, (q-p));
     }
     switch (policy) {
     case SP_BACKGROUND:
         SLOGD("vvv tid %d (%s)", tid, thread_name);
         break;
     case SP_FOREGROUND:
     case SP_AUDIO_APP:
     case SP_AUDIO_SYS:
         SLOGD("^^^ tid %d (%s)", tid, thread_name);
         break;
     case SP_SYSTEM:
         SLOGD("/// tid %d (%s)", tid, thread_name);
         break;
     default:
         SLOGD("??? tid %d (%s)", tid, thread_name);
         break;
     }
 #endif

     if (__sys_supports_schedgroups) {
         if (add_tid_to_cgroup(tid, policy)) {
             if (errno != ESRCH && errno != ENOENT)
                 return -errno;
         }
     } else {
         struct sched_param param;

         param.sched_priority = 0;
         sched_setscheduler(tid,
                            (policy == SP_BACKGROUND) ?
                             SCHED_BATCH : SCHED_NORMAL,
                            &param);
     }

     return 0;
 }

 #else

 /* Stubs for non-Android targets. */

 int set_sched_policy(int tid, SchedPolicy policy)
 {
     return 0;
 }

 int get_sched_policy(int tid, SchedPolicy *policy)
 {
     *policy = SP_SYSTEM_DEFAULT;
     return 0;
 }

 #endif

 const char *get_sched_policy_name(SchedPolicy policy)
 {
     policy = _policy(policy);
     static const char * const strings[SP_CNT] = {
        [SP_BACKGROUND] = "bg",
        [SP_FOREGROUND] = "fg",
        [SP_SYSTEM]     = "  ",
        [SP_AUDIO_APP]  = "aa",
        [SP_AUDIO_SYS]  = "as",
     };
     if ((policy < SP_CNT) && (strings[policy] != NULL))
         return strings[policy];
     else
         return "error";
 }

	/* libs/cutils/sched_policy.c
	**
	** Copyright 2007, The Android Open Source Project
	**
	** Licensed under the Apache License, Version 2.0 (the "License");
	** you may not use this file except in compliance with the License.
	** You may obtain a copy of the License at
	**
	** http://www.apache.org/licenses/LICENSE-2.0
	**
	** Unless required by applicable law or agreed to in writing, software
	** distributed under the License is distributed on an "AS IS" BASIS,
	** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	** See the License for the specific language governing permissions and
	** limitations under the License.
	*/

	#define LOG_TAG "SchedPolicy"

	#include <stdio.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <string.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <cutils/sched_policy.h>
	#include <cutils/log.h>

	/* Re-map SP_DEFAULT to the system default policy, and leave other values unchanged.
	* Call this any place a SchedPolicy is used as an input parameter.
	* Returns the possibly re-mapped policy.
	*/
	static inline SchedPolicy _policy(SchedPolicy p)
	{
	return p == SP_DEFAULT ? SP_SYSTEM_DEFAULT : p;
	}

	#if defined(HAVE_ANDROID_OS) && defined(HAVE_SCHED_H) && defined(HAVE_PTHREADS)

	#include <sched.h>
	#include <pthread.h>

	#ifndef SCHED_NORMAL
	#define SCHED_NORMAL 0
	#endif

	#ifndef SCHED_BATCH
	#define SCHED_BATCH 3
	#endif

	#define POLICY_DEBUG 0

	#define CAN_SET_SP_SYSTEM 0 // non-zero means to implement set_sched_policy(tid, SP_SYSTEM)

	static pthread_once_t the_once = PTHREAD_ONCE_INIT;

	static int __sys_supports_schedgroups = -1;

	// File descriptors open to /dev/cpuctl/../tasks, setup by initialize, or -1 on error.
	static int bg_cgroup_fd = -1;
	static int fg_cgroup_fd = -1;
	#if CAN_SET_SP_SYSTEM
	static int system_cgroup_fd = -1;
	#endif

	/* Add tid to the scheduling group defined by the policy */
	static int add_tid_to_cgroup(int tid, SchedPolicy policy)
	{
	int fd;

	switch (policy) {
	case SP_BACKGROUND:
	fd = bg_cgroup_fd;
	break;
	case SP_FOREGROUND:
	case SP_AUDIO_APP:
	case SP_AUDIO_SYS:
	fd = fg_cgroup_fd;
	break;
	#if CAN_SET_SP_SYSTEM
	case SP_SYSTEM:
	fd = system_cgroup_fd;
	break;
	#endif
	default:
	fd = -1;
	break;
	}

	if (fd < 0) {
	SLOGE("add_tid_to_cgroup failed; policy=%d\n", policy);
	return -1;
	}

	// specialized itoa -- works for tid > 0
	char text[22];
	char *end = text + sizeof(text) - 1;
	char *ptr = end;
	*ptr = '\0';
	while (tid > 0) {
	*--ptr = '0' + (tid % 10);
	tid = tid / 10;
	}

	if (write(fd, ptr, end - ptr) < 0) {
	/*
	* If the thread is in the process of exiting,
	* don't flag an error
	*/
	if (errno == ESRCH)
	return 0;
	SLOGW("add_tid_to_cgroup failed to write '%s' (%s); policy=%d\n",
	ptr, strerror(errno), policy);
	return -1;
	}

	return 0;
	}

	static void __initialize(void) {
	char* filename;
	if (!access("/dev/cpuctl/tasks", F_OK)) {
	__sys_supports_schedgroups = 1;

	#if CAN_SET_SP_SYSTEM
	filename = "/dev/cpuctl/tasks";
	system_cgroup_fd = open(filename, O_WRONLY \| O_CLOEXEC);
	if (system_cgroup_fd < 0) {
	SLOGV("open of %s failed: %s\n", filename, strerror(errno));
	}
	#endif

	filename = "/dev/cpuctl/apps/tasks";
	fg_cgroup_fd = open(filename, O_WRONLY \| O_CLOEXEC);
	if (fg_cgroup_fd < 0) {
	SLOGE("open of %s failed: %s\n", filename, strerror(errno));
	}

	filename = "/dev/cpuctl/apps/bg_non_interactive/tasks";
	bg_cgroup_fd = open(filename, O_WRONLY \| O_CLOEXEC);
	if (bg_cgroup_fd < 0) {
	SLOGE("open of %s failed: %s\n", filename, strerror(errno));
	}
	} else {
	__sys_supports_schedgroups = 0;
	}
	}

	/*
	* Try to get the scheduler group.
	*
	* The data from /proc/<pid>/cgroup looks (something) like:
	* 2:cpu:/bg_non_interactive
	* 1:cpuacct:/
	*
	* We return the part after the "/", which will be an empty string for
	* the default cgroup. If the string is longer than "bufLen", the string
	* will be truncated.
	*/
	static int getSchedulerGroup(int tid, char* buf, size_t bufLen)
	{
	#ifdef HAVE_ANDROID_OS
	char pathBuf[32];
	char lineBuf[256];
	FILE *fp;

	snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
	if (!(fp = fopen(pathBuf, "r"))) {
	return -1;
	}

	while(fgets(lineBuf, sizeof(lineBuf) -1, fp)) {
	char *next = lineBuf;
	char *subsys;
	char *grp;
	size_t len;

	/* Junk the first field */
	if (!strsep(&next, ":")) {
	goto out_bad_data;
	}

	if (!(subsys = strsep(&next, ":"))) {
	goto out_bad_data;
	}

	if (strcmp(subsys, "cpu")) {
	/* Not the subsys we're looking for */
	continue;
	}

	if (!(grp = strsep(&next, ":"))) {
	goto out_bad_data;
	}
	grp++; /* Drop the leading '/' */
	len = strlen(grp);
	grp[len-1] = '\0'; /* Drop the trailing '\n' */

	if (bufLen <= len) {
	len = bufLen - 1;
	}
	strncpy(buf, grp, len);
	buf[len] = '\0';
	fclose(fp);
	return 0;
	}

	SLOGE("Failed to find cpu subsys");
	fclose(fp);
	return -1;
	out_bad_data:
	SLOGE("Bad cgroup data {%s}", lineBuf);
	fclose(fp);
	return -1;
	#else
	errno = ENOSYS;
	return -1;
	#endif
	}

	int get_sched_policy(int tid, SchedPolicy *policy)
	{
	#ifdef HAVE_GETTID
	if (tid == 0) {
	tid = gettid();
	}
	#endif
	pthread_once(&the_once, __initialize);

	if (__sys_supports_schedgroups) {
	char grpBuf[32];
	if (getSchedulerGroup(tid, grpBuf, sizeof(grpBuf)) < 0)
	return -1;
	if (grpBuf[0] == '\0') {
	*policy = SP_SYSTEM;
	} else if (!strcmp(grpBuf, "apps/bg_non_interactive")) {
	*policy = SP_BACKGROUND;
	} else if (!strcmp(grpBuf, "apps")) {
	*policy = SP_FOREGROUND;
	} else {
	errno = ERANGE;
	return -1;
	}
	} else {
	int rc = sched_getscheduler(tid);
	if (rc < 0)
	return -1;
	else if (rc == SCHED_NORMAL)
	*policy = SP_FOREGROUND;
	else if (rc == SCHED_BATCH)
	*policy = SP_BACKGROUND;
	else {
	errno = ERANGE;
	return -1;
	}
	}
	return 0;
	}

	int set_sched_policy(int tid, SchedPolicy policy)
	{
	#ifdef HAVE_GETTID
	if (tid == 0) {
	tid = gettid();
	}
	#endif
	policy = _policy(policy);
	pthread_once(&the_once, __initialize);

	#if POLICY_DEBUG
	char statfile[64];
	char statline[1024];
	char thread_name[255];
	int fd;

	sprintf(statfile, "/proc/%d/stat", tid);
	memset(thread_name, 0, sizeof(thread_name));

	fd = open(statfile, O_RDONLY);
	if (fd >= 0) {
	int rc = read(fd, statline, 1023);
	close(fd);
	statline[rc] = 0;
	char *p = statline;
	char *q;

	for (p = statline; *p != '('; p++);
	p++;
	for (q = p; *q != ')'; q++);

	strncpy(thread_name, p, (q-p));
	}
	switch (policy) {
	case SP_BACKGROUND:
	SLOGD("vvv tid %d (%s)", tid, thread_name);
	break;
	case SP_FOREGROUND:
	case SP_AUDIO_APP:
	case SP_AUDIO_SYS:
	SLOGD("^^^ tid %d (%s)", tid, thread_name);
	break;
	case SP_SYSTEM:
	SLOGD("/// tid %d (%s)", tid, thread_name);
	break;
	default:
	SLOGD("??? tid %d (%s)", tid, thread_name);
	break;
	}
	#endif

	if (__sys_supports_schedgroups) {
	if (add_tid_to_cgroup(tid, policy)) {
	if (errno != ESRCH && errno != ENOENT)
	return -errno;
	}
	} else {
	struct sched_param param;

	param.sched_priority = 0;
	sched_setscheduler(tid,
	(policy == SP_BACKGROUND) ?
	SCHED_BATCH : SCHED_NORMAL,
	&param);
	}

	return 0;
	}

	#else

	/* Stubs for non-Android targets. */

	int set_sched_policy(int tid, SchedPolicy policy)
	{
	return 0;
	}

	int get_sched_policy(int tid, SchedPolicy *policy)
	{
	*policy = SP_SYSTEM_DEFAULT;
	return 0;
	}

	#endif

	const char *get_sched_policy_name(SchedPolicy policy)
	{
	policy = _policy(policy);
	static const char * const strings[SP_CNT] = {
	[SP_BACKGROUND] = "bg",
	[SP_FOREGROUND] = "fg",
	[SP_SYSTEM] = " ",
	[SP_AUDIO_APP] = "aa",
	[SP_AUDIO_SYS] = "as",
	};
	if ((policy < SP_CNT) && (strings[policy] != NULL))
	return strings[policy];
	else
	return "error";
	}