QT+LINUX无法设置线程优先级

[pishuli]

qt4.8+ubuntu在编程时设置优先级模式无效，查看了一下说明文档如下，感觉到不可思议，请大虾指定确认，
如果可以设置优先级，请告知方法，谢谢。
The effect of the priority parameter is dependent on the operating system's scheduling policy. In particular, the priority will be ignored on systems that do not support thread priorities (such as on Linux, see http://linux.die.net/man/2/sched_setscheduler for more details).

This function was introduced in Qt 4.1.

[在飞的特拉斯]

setPriority(Priority priority) 如果系统不支持,你设置了也没用,如果系统支持,就用setPriority(Priority priority)就可以了.

[pishuli]

引用 1 楼 mqdsg 的回复:

setPriority(Priority priority) 如果系统不支持,你设置了也没用,如果系统支持,就用setPriority(Priority priority)就可以了.

谢谢你的回复，你回复的内容我知道，我有疑问的是linux的SCHED_RR和SCHED_FIFO调度是支持优先级的，为什么QT的手册里面说linux不支持任务优先级。

[pishuli]

求大神解答，顶上去

[在飞的特拉斯]

In particular, the priority will be ignored on systems that do not support thread priorities
上面这段话应当讲的是如果linux系统未定义下面这个宏,即为 不支持.
QT_HAS_THREAD_PRIORITY_SCHEDULING
给你找到一篇文章解释:
http://blog.chinaunix.net/uid-25909722-id-3025534.html

对应的qt代码如下:

#if defined(QT_HAS_THREAD_PRIORITY_SCHEDULING)
    switch (priority) {
    case InheritPriority:
        {
            pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
            break;
        }

    default:
        {
            int sched_policy;
            if (pthread_attr_getschedpolicy(&attr, &sched_policy) != 0) {
                // failed to get the scheduling policy, don't bother
                // setting the priority
                qWarning("QThread::start: Cannot determine default scheduler policy");
                break;
            }

            int prio;
            if (!calculateUnixPriority(priority, &sched_policy, &prio)) {
                // failed to get the scheduling parameters, don't
                // bother setting the priority
                qWarning("QThread::start: Cannot determine scheduler priority range");
                break;
            }

            sched_param sp;
            sp.sched_priority = prio;

            if (pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED) != 0
                || pthread_attr_setschedpolicy(&attr, sched_policy) != 0
                || pthread_attr_setschedparam(&attr, &sp) != 0) {
                // could not set scheduling hints, fallback to inheriting them
                // we'll try again from inside the thread
                pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);
                d->priority = Priority(priority | ThreadPriorityResetFlag);
            }
            break;
        }
    }
#endif // QT_HAS_THREAD_PRIORITY_SCHEDULING