libcutils: Move sched_policy functions into libprocessgroup

Move functions operating on cgroups from sched_policy.h in libcutils
into sched_policy_ctrl.h under libprocessgroup. This consolidates
cgroup-related functionality inside libprocessgroup.

Bug: 111307099
Test: builds, boots

Merged-In: Iba75f33281162b889989214d0325a5973d53ed2d
Change-Id: Iba75f33281162b889989214d0325a5973d53ed2d
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

1 files changed, 476 insertions, 0 deletions

diff --git a/libprocessgroup/sched_policy.cpp b/libprocessgroup/sched_policy.cpp
new file mode 100644
index 000000000..f95d7e48f
--- /dev/null
+++ b/libprocessgroup/sched_policy.cpp
@@ -0,0 +1,476 @@
+/*
+** 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 <processgroup/sched_policy.h>
+
+#define LOG_TAG "SchedPolicy"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <android-base/macros.h>
+#include <log/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(__ANDROID__)
+
+#include <pthread.h>
+#include <sched.h>
+#include <sys/prctl.h>
+
+#define POLICY_DEBUG 0
+
+// timer slack value in nS enforced when the thread moves to background
+#define TIMER_SLACK_BG 40000000
+#define TIMER_SLACK_FG 50000
+
+static pthread_once_t the_once = PTHREAD_ONCE_INIT;
+
+static int __sys_supports_timerslack = -1;
+
+// File descriptors open to /dev/cpuset/../tasks, setup by initialize, or -1 on error
+static int system_bg_cpuset_fd = -1;
+static int bg_cpuset_fd = -1;
+static int fg_cpuset_fd = -1;
+static int ta_cpuset_fd = -1; // special cpuset for top app
+static int rs_cpuset_fd = -1;  // special cpuset for screen off restrictions
+
+// File descriptors open to /dev/stune/../tasks, setup by initialize, or -1 on error
+static int bg_schedboost_fd = -1;
+static int fg_schedboost_fd = -1;
+static int ta_schedboost_fd = -1;
+static int rt_schedboost_fd = -1;
+
+/* Add tid to the scheduling group defined by the policy */
+static int add_tid_to_cgroup(int tid, int fd)
+{
+    if (fd < 0) {
+        SLOGE("add_tid_to_cgroup failed; fd=%d\n", fd);
+        errno = EINVAL;
+        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); fd=%d\n",
+              ptr, strerror(errno), fd);
+        errno = EINVAL;
+        return -1;
+    }
+
+    return 0;
+}
+
+/*
+    If CONFIG_CPUSETS for Linux kernel is set, "tasks" can be found under
+    /dev/cpuset mounted in init.rc; otherwise, that file does not exist
+    even though the directory, /dev/cpuset, is still created (by init.rc).
+
+    A couple of other candidates (under cpuset mount directory):
+        notify_on_release
+        release_agent
+
+    Yet another way to decide if cpuset is enabled is to parse
+    /proc/self/status and search for lines begin with "Mems_allowed".
+
+    If CONFIG_PROC_PID_CPUSET is set, the existence "/proc/self/cpuset" can
+    be used to decide if CONFIG_CPUSETS is set, so we don't have a dependency
+    on where init.rc mounts cpuset. That's why we'd better require this
+    configuration be set if CONFIG_CPUSETS is set.
+
+    In older releases, this was controlled by build-time configuration.
+ */
+bool cpusets_enabled() {
+    static bool enabled = (access("/dev/cpuset/tasks", F_OK) == 0);
+
+    return enabled;
+}
+
+/*
+    Similar to CONFIG_CPUSETS above, but with a different configuration
+    CONFIG_CGROUP_SCHEDTUNE that's in Android common Linux kernel and Linaro
+    Stable Kernel (LSK), but not in mainline Linux as of v4.9.
+
+    In older releases, this was controlled by build-time configuration.
+ */
+bool schedboost_enabled() {
+    static bool enabled = (access("/dev/stune/tasks", F_OK) == 0);
+
+    return enabled;
+}
+
+static void __initialize() {
+    const char* filename;
+
+    if (cpusets_enabled()) {
+        if (!access("/dev/cpuset/tasks", W_OK)) {
+
+            filename = "/dev/cpuset/foreground/tasks";
+            fg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+            filename = "/dev/cpuset/background/tasks";
+            bg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+            filename = "/dev/cpuset/system-background/tasks";
+            system_bg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+            filename = "/dev/cpuset/top-app/tasks";
+            ta_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+            filename = "/dev/cpuset/restricted/tasks";
+            rs_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+
+            if (schedboost_enabled()) {
+                filename = "/dev/stune/top-app/tasks";
+                ta_schedboost_fd = open(filename, O_WRONLY | O_CLOEXEC);
+                filename = "/dev/stune/foreground/tasks";
+                fg_schedboost_fd = open(filename, O_WRONLY | O_CLOEXEC);
+                filename = "/dev/stune/background/tasks";
+                bg_schedboost_fd = open(filename, O_WRONLY | O_CLOEXEC);
+                filename = "/dev/stune/rt/tasks";
+                rt_schedboost_fd = open(filename, O_WRONLY | O_CLOEXEC);
+            }
+        }
+    }
+
+    char buf[64];
+    snprintf(buf, sizeof(buf), "/proc/%d/timerslack_ns", getpid());
+    __sys_supports_timerslack = !access(buf, W_OK);
+}
+
+/*
+ * Returns the path under the requested cgroup subsystem (if it exists)
+ *
+ * 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 getCGroupSubsys(int tid, const char* subsys, char* buf, size_t bufLen)
+{
+#if defined(__ANDROID__)
+    char pathBuf[32];
+    char lineBuf[256];
+    FILE *fp;
+
+    snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
+    if (!(fp = fopen(pathBuf, "re"))) {
+        return -1;
+    }
+
+    while(fgets(lineBuf, sizeof(lineBuf) -1, fp)) {
+        char *next = lineBuf;
+        char *found_subsys;
+        char *grp;
+        size_t len;
+
+        /* Junk the first field */
+        if (!strsep(&next, ":")) {
+            goto out_bad_data;
+        }
+
+        if (!(found_subsys = strsep(&next, ":"))) {
+            goto out_bad_data;
+        }
+
+        if (strcmp(found_subsys, subsys)) {
+            /* 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 subsys %s", 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)
+{
+    if (tid == 0) {
+        tid = gettid();
+    }
+    pthread_once(&the_once, __initialize);
+
+    char grpBuf[32];
+
+    grpBuf[0] = '\0';
+    if (schedboost_enabled()) {
+        if (getCGroupSubsys(tid, "schedtune", grpBuf, sizeof(grpBuf)) < 0) return -1;
+    }
+    if ((grpBuf[0] == '\0') && cpusets_enabled()) {
+        if (getCGroupSubsys(tid, "cpuset", grpBuf, sizeof(grpBuf)) < 0) return -1;
+    }
+    if (grpBuf[0] == '\0') {
+        *policy = SP_FOREGROUND;
+    } else if (!strcmp(grpBuf, "foreground")) {
+        *policy = SP_FOREGROUND;
+    } else if (!strcmp(grpBuf, "system-background")) {
+        *policy = SP_SYSTEM;
+    } else if (!strcmp(grpBuf, "background")) {
+        *policy = SP_BACKGROUND;
+    } else if (!strcmp(grpBuf, "top-app")) {
+        *policy = SP_TOP_APP;
+    } else {
+        errno = ERANGE;
+        return -1;
+    }
+    return 0;
+}
+
+int set_cpuset_policy(int tid, SchedPolicy policy)
+{
+    // in the absence of cpusets, use the old sched policy
+    if (!cpusets_enabled()) {
+        return set_sched_policy(tid, policy);
+    }
+
+    if (tid == 0) {
+        tid = gettid();
+    }
+    policy = _policy(policy);
+    pthread_once(&the_once, __initialize);
+
+    int fd = -1;
+    int boost_fd = -1;
+    switch (policy) {
+    case SP_BACKGROUND:
+        fd = bg_cpuset_fd;
+        boost_fd = bg_schedboost_fd;
+        break;
+    case SP_FOREGROUND:
+    case SP_AUDIO_APP:
+    case SP_AUDIO_SYS:
+        fd = fg_cpuset_fd;
+        boost_fd = fg_schedboost_fd;
+        break;
+    case SP_TOP_APP :
+        fd = ta_cpuset_fd;
+        boost_fd = ta_schedboost_fd;
+        break;
+    case SP_SYSTEM:
+        fd = system_bg_cpuset_fd;
+        break;
+    case SP_RESTRICTED:
+        fd = rs_cpuset_fd;
+        break;
+    default:
+        boost_fd = fd = -1;
+        break;
+    }
+
+    if (add_tid_to_cgroup(tid, fd) != 0) {
+        if (errno != ESRCH && errno != ENOENT)
+            return -errno;
+    }
+
+    if (schedboost_enabled()) {
+        if (boost_fd > 0 && add_tid_to_cgroup(tid, boost_fd) != 0) {
+            if (errno != ESRCH && errno != ENOENT)
+                return -errno;
+        }
+    }
+
+    return 0;
+}
+
+static void set_timerslack_ns(int tid, unsigned long slack) {
+    // v4.6+ kernels support the /proc/<tid>/timerslack_ns interface.
+    // TODO: once we've backported this, log if the open(2) fails.
+    if (__sys_supports_timerslack) {
+        char buf[64];
+        snprintf(buf, sizeof(buf), "/proc/%d/timerslack_ns", tid);
+        int fd = open(buf, O_WRONLY | O_CLOEXEC);
+        if (fd != -1) {
+            int len = snprintf(buf, sizeof(buf), "%lu", slack);
+            if (write(fd, buf, len) != len) {
+                SLOGE("set_timerslack_ns write failed: %s\n", strerror(errno));
+            }
+            close(fd);
+            return;
+        }
+    }
+
+    // TODO: Remove when /proc/<tid>/timerslack_ns interface is backported.
+    if ((tid == 0) || (tid == gettid())) {
+        if (prctl(PR_SET_TIMERSLACK, slack) == -1) {
+            SLOGE("set_timerslack_ns prctl failed: %s\n", strerror(errno));
+        }
+    }
+}
+
+int set_sched_policy(int tid, SchedPolicy policy)
+{
+    if (tid == 0) {
+        tid = gettid();
+    }
+    policy = _policy(policy);
+    pthread_once(&the_once, __initialize);
+
+#if POLICY_DEBUG
+    char statfile[64];
+    char statline[1024];
+    char thread_name[255];
+
+    snprintf(statfile, sizeof(statfile), "/proc/%d/stat", tid);
+    memset(thread_name, 0, sizeof(thread_name));
+
+    int fd = open(statfile, O_RDONLY | O_CLOEXEC);
+    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:
+    case SP_TOP_APP:
+        SLOGD("^^^ tid %d (%s)", tid, thread_name);
+        break;
+    case SP_SYSTEM:
+        SLOGD("/// tid %d (%s)", tid, thread_name);
+        break;
+    case SP_RT_APP:
+	SLOGD("RT  tid %d (%s)", tid, thread_name);
+	break;
+    default:
+        SLOGD("??? tid %d (%s)", tid, thread_name);
+        break;
+    }
+#endif
+
+    if (schedboost_enabled()) {
+        int boost_fd = -1;
+        switch (policy) {
+        case SP_BACKGROUND:
+            boost_fd = bg_schedboost_fd;
+            break;
+        case SP_FOREGROUND:
+        case SP_AUDIO_APP:
+        case SP_AUDIO_SYS:
+            boost_fd = fg_schedboost_fd;
+            break;
+        case SP_TOP_APP:
+            boost_fd = ta_schedboost_fd;
+            break;
+        case SP_RT_APP:
+	    boost_fd = rt_schedboost_fd;
+	    break;
+        default:
+            boost_fd = -1;
+            break;
+        }
+
+        if (boost_fd > 0 && add_tid_to_cgroup(tid, boost_fd) != 0) {
+            if (errno != ESRCH && errno != ENOENT)
+                return -errno;
+        }
+
+    }
+
+    set_timerslack_ns(tid, policy == SP_BACKGROUND ? TIMER_SLACK_BG : TIMER_SLACK_FG);
+
+    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 kSchedPolicyNames[] = {
+            [SP_BACKGROUND] = "bg", [SP_FOREGROUND] = "fg", [SP_SYSTEM] = "  ",
+            [SP_AUDIO_APP] = "aa",  [SP_AUDIO_SYS] = "as",  [SP_TOP_APP] = "ta",
+            [SP_RT_APP] = "rt",     [SP_RESTRICTED] = "rs",
+    };
+    static_assert(arraysize(kSchedPolicyNames) == SP_CNT, "missing name");
+    if (policy < SP_BACKGROUND || policy >= SP_CNT) {
+        return "error";
+    }
+    return kSchedPolicyNames[policy];
+}