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Commit f1b56449 authored by Glenn Kasten's avatar Glenn Kasten
Browse files

Scheduling group cleanup 

The C++ API for scheduling groups is going away, so use the C API.

Renumber THREAD_GROUP_* constants to have the same values as SP_*.
They are @hide so this should be OK.

The old THREAD_GROUP_FG_BOOST constant is removed, and replaced by a
(private) THREAD_GROUP_FOREGROUND constant that is just a placeholder
to correspond to SP_FOREGROUND.  It is not usable at this level.

Improved performance of android_os_Process_setProcessGroup:
avoid unnecessary syscall to getpriority for each tid.

Fixed error handling in android_os_Process_setThreadGroup.
It raises an exception if set_sched_policy() returns an error.

Add comments and fix typos in existing comments.

Change-Id: Ib922e92c945985c695ef0addbd2b83b8e82865f8
parent 362bcb06

core/java/android/os/Process.java

+33 −11
Original line number Diff line number Diff line
@@ -266,25 +266,38 @@ public class Process { 
     */

    public static final int SCHED_IDLE = 5;



    // Keep in sync with SP_* constants of enum type SchedPolicy

    // declared in system/core/include/cutils/sched_policy.h,

    // except THREAD_GROUP_DEFAULT does not correspond to any SP_* value.



    /**

     * Default thread group - gets a 'normal' share of the CPU

     * Default thread group -

     * has meaning with setProcessGroup() only, cannot be used with setThreadGroup().

     * When used with setProcessGroup(), the group of each thread in the process

     * is conditionally changed based on that thread's current priority, as follows:

     * threads with priority numerically less than THREAD_PRIORITY_BACKGROUND

     * are moved to foreground thread group.  All other threads are left unchanged.

     * @hide

     */

    public static final int THREAD_GROUP_DEFAULT = 0;

    public static final int THREAD_GROUP_DEFAULT = -1;



    /**

     * Background non-interactive thread group - All threads in

     * Background thread group - All threads in

     * this group are scheduled with a reduced share of the CPU.

     * Value is same as constant SP_BACKGROUND of enum SchedPolicy.

     * FIXME rename to THREAD_GROUP_BACKGROUND.

     * @hide

     */

    public static final int THREAD_GROUP_BG_NONINTERACTIVE = 1;

    public static final int THREAD_GROUP_BG_NONINTERACTIVE = 0;



    /**

     * Foreground 'boost' thread group - All threads in

     * this group are scheduled with an increased share of the CPU

     * Foreground thread group - All threads in

     * this group are scheduled with a normal share of the CPU.

     * Value is same as constant SP_FOREGROUND of enum SchedPolicy.

     * Not used at this level.

     * @hide

     **/

    public static final int THREAD_GROUP_FG_BOOST = 2;

    private static final int THREAD_GROUP_FOREGROUND = 1;



    public static final int SIGNAL_QUIT = 3;

    public static final int SIGNAL_KILL = 9;
@@ -672,28 +685,37 @@ public class Process { 
    /**

     * Sets the scheduling group for a thread.

     * @hide

     * @param tid The indentifier of the thread/process to change.

     * @param group The target group for this thread/process.

     * @param tid The identifier of the thread to change.

     * @param group The target group for this thread from THREAD_GROUP_*.

     * 

     * @throws IllegalArgumentException Throws IllegalArgumentException if

     * <var>tid</var> does not exist.

     * @throws SecurityException Throws SecurityException if your process does

     * not have permission to modify the given thread, or to use the given

     * priority.

     * If the thread is a thread group leader, that is it's gettid() == getpid(),

     * then the other threads in the same thread group are _not_ affected.

     */

    public static final native void setThreadGroup(int tid, int group)

            throws IllegalArgumentException, SecurityException;



    /**

     * Sets the scheduling group for a process and all child threads

     * @hide

     * @param pid The indentifier of the process to change.

     * @param group The target group for this process.

     * @param pid The identifier of the process to change.

     * @param group The target group for this process from THREAD_GROUP_*.

     * 

     * @throws IllegalArgumentException Throws IllegalArgumentException if

     * <var>tid</var> does not exist.

     * @throws SecurityException Throws SecurityException if your process does

     * not have permission to modify the given thread, or to use the given

     * priority.

     *

     * group == THREAD_GROUP_DEFAULT means to move all non-background priority

     * threads to the foreground scheduling group, but to leave background

     * priority threads alone.  group == THREAD_GROUP_BG_NONINTERACTIVE moves all

     * threads, regardless of priority, to the background scheduling group.

     * group == THREAD_GROUP_FOREGROUND is not allowed.

     */

    public static final native void setProcessGroup(int pid, int group)

            throws IllegalArgumentException, SecurityException;

core/jni/android_util_Process.cpp

+27 −13
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <binder/IPCThreadState.h>

#include <binder/ProcessState.h>

#include <binder/IServiceManager.h>

#include <cutils/sched_policy.h>

#include <utils/String8.h>

#include <utils/Vector.h>
@@ -49,6 +50,8 @@ Mutex gKeyCreateMutex; 
static pthread_key_t gBgKey = -1;

#endif



// For both of these, err should be in the errno range (positive), not a status_t (negative)



static void signalExceptionForPriorityError(JNIEnv* env, int err)

{

    switch (err) {
@@ -168,27 +171,36 @@ jint android_os_Process_getGidForName(JNIEnv* env, jobject clazz, jstring name) 
    return -1;

}



void android_os_Process_setThreadGroup(JNIEnv* env, jobject clazz, int pid, jint grp)

void android_os_Process_setThreadGroup(JNIEnv* env, jobject clazz, int tid, jint grp)

{

    int res = androidSetThreadSchedulingGroup(pid, grp);

    ALOGV("%s tid=%d grp=%d", __func__, tid, grp);

    SchedPolicy sp = (SchedPolicy) grp;

    int res = set_sched_policy(tid, sp);

    if (res != NO_ERROR) {

        signalExceptionForGroupError(env, res == BAD_VALUE ? EINVAL : errno);

        return;

        signalExceptionForGroupError(env, -res);

    }

}



void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jint grp)

{

    ALOGV("%s pid=%d grp=%d", __func__, pid, grp);

    DIR *d;

    FILE *fp;

    char proc_path[255];

    struct dirent *de;



    if (grp > ANDROID_TGROUP_MAX || grp < 0) {

    if ((grp == SP_FOREGROUND) || (grp > SP_MAX)) {

        signalExceptionForGroupError(env, EINVAL);

        return;

    }



    bool isDefault = false;

    if (grp < 0) {

        grp = SP_FOREGROUND;

        isDefault = true;

    }

    SchedPolicy sp = (SchedPolicy) grp;



#if POLICY_DEBUG

    char cmdline[32];

    int fd;
@@ -203,7 +215,7 @@ void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jin 
        close(fd);

    }



    if (grp == ANDROID_TGROUP_BG_NONINTERACT) {

    if (sp == SP_BACKGROUND) {

        ALOGD("setProcessGroup: vvv pid %d (%s)", pid, cmdline);

    } else {

        ALOGD("setProcessGroup: ^^^ pid %d (%s)", pid, cmdline);
@@ -230,16 +242,18 @@ void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jin 
            continue;

        }



        if (isDefault) {

            t_pri = getpriority(PRIO_PROCESS, t_pid);



        if (grp == ANDROID_TGROUP_DEFAULT &&

            t_pri >= ANDROID_PRIORITY_BACKGROUND) {

            if (t_pri >= ANDROID_PRIORITY_BACKGROUND) {

                // This task wants to stay at background

                continue;

            }

        }



        if (androidSetThreadSchedulingGroup(t_pid, grp) != NO_ERROR) {

            signalExceptionForGroupError(env, errno);

        int err = set_sched_policy(t_pid, sp);

        if (err != NO_ERROR) {

            signalExceptionForGroupError(env, -err);

            break;

        }

    }