#define _REENTRANT
#include
#include
#include
#include
void *thread_function(void *arg);
char message[] = "Hello World";
int main() {
int res;
pthread_t a_thread;
void *thread_result;
pthread_attr_t thread_attr;
int max_priority;
int min_priority;
struct sched_param scheduling_value;
res = pthread_attr_init(&thread_attr);
res = pthread_attr_setschedpolicy(&thread_attr, SCHED_OTHER);
res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
res = pthread_create(&a_thread, &thread_attr, thread_function, (void *)message);
printf("Waiting 1 \n");
max_priority = sched_get_priority_max(SCHED_OTHER);
min_priority = sched_get_priority_min(SCHED_OTHER);
scheduling_value.sched_priority = max_priority；[color=seagreen]（这里不管我设优先级为最高或者最低，或者默认，结果都一样）
//scheduling_value.sched_priority = min_priority;
res = pthread_attr_setschedparam(&thread_attr, &scheduling_value);
(void)pthread_attr_destroy(&thread_attr);
sleep(1);
printf("Waiting 2\n");
exit(EXIT_SUCCESS);
}[/color]
void *thread_function(void *arg) {
printf("thread_function is running. Argument was %s\n", (char *)arg);
sleep(1);
printf("Waiting 3\n");
pthread_exit(NULL);
}
结果如下：
Waiting 1
thread_function is running. Argument was Hello World
Waiting 2
Waiting 3
Waiting 3
疑问有3：
1，为什么创建新线程之后，无论我设优先级是什么，都是原先的线程先运行
2，线程创建之后，和原先线程之间是怎么轮询的
3：为什么我这个结果输出为多一个
Waiting 3
麻烦大家帮忙看看
reaperzero 于 2010-11-12 10:13:16发表:
学习下，，，，
deepwhite 于 2010-11-12 09:42:02发表:
[i=s] 本帖最后由 deepwhite 于 2010-11-12 13:36 编辑 [/i]
参考一下下面的两篇文章。
http://www.yolinux.com/TUTORIALS/LinuxTutorialPosixThreads.html
http://www.icir.org/gregor/tools/pthread-scheduling.html
最后有一点，用户态的线程和进程对内核来讲，在调度上是一样的，所以轮询之类的和普通的多进程之间没有什么差别。
I will only discuss the ntpl (native posix thread library) implementation, which is the default pthread implementation used in current glibcs. The nptl implementation only uses a 1:1 thread model. The scheduler handles everythread as if it were a process. Therefor only the supported scope isPTHREAD_SCOPE_SYSTEM. The default scheduling policy is SCHED_OTHER, which is the default Linux scheduler. The nptl implementation can utilizemultiple CPUs.
It is possible to assign a thread aSCHED_FIFO and SCHED_RR policy. Since the scheduler handles every thread as if it were a process, a thread with one of these policies will be handled like a process with realtime schduling priority (see [2]). I.e the threadwill content for the CPU with all other procesess and not with thethreads of the same process. This implies that a threadcould starve other processes! Essentially the pthread_set_schedparam()call maps to the sched_setscheduler() call. This operation requires root privileges, since it can have a vital impact on thewhole system.
For SCHED_OTHER the allowed min and max priorities are 0. Therefor itis not possible to change the priority. SCHED_FF or SCHED_RR have an allowed range of 1 ... 99 (see sched_get_priority_max(2) andsched_get_priority_min(2)).