问个线程优先级的问题

hunterhu3000

我用pthread_attr_t设置好调度策略和优先级之后读出来为什么不对？
环境是red hat Linux 内核2.6.9-5

代码：
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <pthread.h>
#include <assert.h>

pthread_t taskCreate(void (*functionPTR)(void), int priority)
{
    pthread_t               taskId;
    int       policy;
    pthread_attr_t          attr;   
    struct   sched_param    param;   
   
    assert ( pthread_attr_init(&attr) == 0 );   
    pthread_attr_setschedpolicy(&attr, SCHED_RR);  
    assert ( pthread_attr_getschedparam(&attr, &param) == 0);
    param.sched_priority   =  priority;
    pthread_attr_setschedparam(&attr, &param);   
    assert( pthread_create(&taskId, &attr, (void*)functionPTR, NULL) == 0 );
    pthread_getschedparam(taskId, &policy, &param);
    printf("policy = %d, priority = %d\n",policy,param.sched_priority);

    pthread_attr_getschedpolicy(&attr, &policy);
    pthread_attr_getschedparam(&attr, &param);
    printf("policy = %d, priority = %d\n",policy,param.sched_priority);
    pthread_attr_destroy(&attr);  
    return taskId;
}

void funcA()
{
    sleep(1);
}
int main()
{
    taskCreate(funcA, 99);
    return 0;
}


运行：
[root@ANY ~]# uname -a
Linux ANY 2.6.9-5.ELsmp #1 SMP Wed Jan 5 19:30:39 EST 2005 i686 athlon i386 GNU/Linux
[root@ANY ~]# ./taskLib_wrong
policy = 0, priority = 0
policy = 2, priority = 99


可以看出attr已经被修改了，但是通过thread id读却仍旧是没有优先级的OTHER,是我有地方写错了还是create thread和系统或者内核或者编译器什么的有关系？