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我正在开发使用上下文切换作为基本方法的用户空间预先线程库(光纤)。为此我写了一个调度程序。但是,它没有按预期执行。我能为此提出任何建议吗? 的的thread_t所使用的结构是:为用户空间线程库编写调度程序
typedef struct thread_t {
int thr_id;
int thr_usrpri;
int thr_cpupri;
int thr_totalcpu;
ucontext_t thr_context;
void * thr_stack;
int thr_stacksize;
struct thread_t *thr_next;
struct thread_t *thr_prev;
} thread_t;
调度功能如下:
void schedule(void)
{
thread_t *t1, *t2;
thread_t * newthr = NULL;
int newpri = 127;
struct itimerval tm;
ucontext_t dummy;
sigset_t sigt;
t1 = ready_q;
// Select the thread with higest priority
while (t1 != NULL)
{
if (newpri > t1->thr_usrpri + t1->thr_cpupri)
{
newpri = t1->thr_usrpri + t1->thr_cpupri;
newthr = t1;
}
t1 = t1->thr_next;
}
if (newthr == NULL)
{
if (current_thread == NULL)
{
// No more threads? (stop itimer)
tm.it_interval.tv_usec = 0;
tm.it_interval.tv_sec = 0;
tm.it_value.tv_usec = 0; // ZERO Disable
tm.it_value.tv_sec = 0;
setitimer(ITIMER_PROF, &tm, NULL);
}
return;
}
else
{
// TO DO :: Reenabling of signals must be done.
// Switch to new thread
if (current_thread != NULL)
{
t2 = current_thread;
current_thread = newthr;
timeq = 0;
sigemptyset(&sigt);
sigaddset(&sigt, SIGPROF);
sigprocmask(SIG_UNBLOCK, &sigt, NULL);
swapcontext(&(t2->thr_context), &(current_thread->thr_context));
}
else
{
// No current thread? might be terminated
current_thread = newthr;
timeq = 0;
sigemptyset(&sigt);
sigaddset(&sigt, SIGPROF);
sigprocmask(SIG_UNBLOCK, &sigt, NULL);
swapcontext(&(dummy), &(current_thread->thr_context));
}
}
}
它是干什么的“没有预料到”? –
那么,一旦主线程将控制传递给其他线程,它就不会长时间回调。也许优先倒置。虽然不确定。 – uyetch