eclair snapshot
diff --git a/libcutils/sched_policy.c b/libcutils/sched_policy.c
new file mode 100644
index 0000000..64d9bb7
--- /dev/null
+++ b/libcutils/sched_policy.c
@@ -0,0 +1,221 @@
+
+/* 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.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#define LOG_TAG "SchedPolicy"
+#include "cutils/log.h"
+
+#ifdef HAVE_SCHED_H
+
+#include <sched.h>
+
+#include <cutils/sched_policy.h>
+
+#ifndef SCHED_NORMAL
+ #define SCHED_NORMAL 0
+#endif
+
+#ifndef SCHED_BATCH
+ #define SCHED_BATCH 3
+#endif
+
+#define POLICY_DEBUG 0
+
+static int __sys_supports_schedgroups = -1;
+
+static int add_tid_to_cgroup(int tid, const char *grp_name)
+{
+ int fd;
+ char path[255];
+ char text[64];
+
+ sprintf(path, "/dev/cpuctl/%s/tasks", grp_name);
+
+ if ((fd = open(path, O_WRONLY)) < 0) {
+ LOGE("add_tid_to_cgroup failed to open '%s' (%s)\n", path, strerror(errno));
+ return -1;
+ }
+
+ sprintf(text, "%d", tid);
+ if (write(fd, text, strlen(text)) < 0) {
+ close(fd);
+ return -1;
+ }
+
+ close(fd);
+ return 0;
+}
+
+static inline void initialize()
+{
+ if (__sys_supports_schedgroups < 0) {
+ if (!access("/dev/cpuctl/tasks", F_OK)) {
+ __sys_supports_schedgroups = 1;
+ } else {
+ __sys_supports_schedgroups = 0;
+ }
+ }
+}
+
+/*
+ * Try to get the scheduler group.
+ *
+ * The data from /proc/<pid>/cgroup looks like:
+ * 2:cpu:/bg_non_interactive
+ *
+ * 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 readBuf[256];
+ ssize_t count;
+ int fd;
+
+ snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
+ if ((fd = open(pathBuf, O_RDONLY)) < 0) {
+ return -1;
+ }
+
+ count = read(fd, readBuf, sizeof(readBuf));
+ if (count <= 0) {
+ close(fd);
+ errno = ENODATA;
+ return -1;
+ }
+ close(fd);
+
+ readBuf[--count] = '\0'; /* remove the '\n', now count==strlen */
+
+ char* cp = strchr(readBuf, '/');
+ if (cp == NULL) {
+ readBuf[sizeof(readBuf)-1] = '\0';
+ errno = ENODATA;
+ return -1;
+ }
+
+ memcpy(buf, cp+1, count); /* count-1 for cp+1, count+1 for NUL */
+ return 0;
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+int get_sched_policy(int tid, SchedPolicy *policy)
+{
+ initialize();
+
+ if (__sys_supports_schedgroups) {
+ char grpBuf[32];
+ if (getSchedulerGroup(tid, grpBuf, sizeof(grpBuf)) < 0)
+ return -1;
+ if (grpBuf[0] == '\0') {
+ *policy = SP_FOREGROUND;
+ } else if (!strcmp(grpBuf, "bg_non_interactive")) {
+ *policy = SP_BACKGROUND;
+ } 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)
+{
+ 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));
+ }
+ if (policy == SP_BACKGROUND) {
+ LOGD("vvv tid %d (%s)", tid, thread_name);
+ } else if (policy == SP_FOREGROUND) {
+ LOGD("^^^ tid %d (%s)", tid, thread_name);
+ } else {
+ LOGD("??? tid %d (%s)", tid, thread_name);
+ }
+#endif
+
+ if (__sys_supports_schedgroups) {
+ const char *grp = "";
+
+ if (policy == SP_BACKGROUND) {
+ grp = "bg_non_interactive";
+ }
+
+ if (add_tid_to_cgroup(tid, grp)) {
+ 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,
+ ¶m);
+ }
+
+ return 0;
+}
+
+#endif /* HAVE_SCHED_H */