I am attempting to set up a program that has 3 threads. The first thread is a receiver process that listens on a UDP port and puts a struct on a one of two queues depending on a flag in the packet. The other two threads block on a pthread_cond_t (that is signaled when a message is added to their queue), then take messages off their corresponding queues and perform a fixed amount of computation. I am setting thread priorities as follows: pthread_t tid_processor; struct sched_param sparam; pthread_attr_t tattr; pthread_attr_init(&tattr); pthread_attr_getschedparam(&tattr, &sparam); sparam.sched_priority = SOME_THREAD_PRIORITY; pthread_attr_setschedpolicy(&tattr, SCHED_FIFO); pthread_attr_setschedparam(&tattr, &sparam)); pthread_create(&tid, &tattr, &thread_function, NULL ); I set the receiver thread to the highest priority, then one of the processor threads is higher than the other. I have two questions about this situation: 1) Are pthread priorities reversed from Linux priorities. In other words, does a lower number mean a higher priority? 2) Will a higher priority thread preempt the execution of a lower priority thread? With the behavior I am seeing now, this seems to not be the case. If the lower priority processing thread begins execution first the higher priority processing thread will not begin until it has finished. Though I correctly receive messages and put them into the queue making this all the more puzzling. Thank you for any help with my problem! Let me know if you need more information or detail in my questions. Jonathan Walsh Member Engineering Staff Lockheed Martin Advanced Technology Laboratories - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
