pthread_setcurrency生效问题

2012-12-03 11:43:01 194 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

clark2009 墨衍会员 · AI 创作全网分发关注 + 加入社区

UNPV2 129页set_concurrency无法生效。我的虚拟机是单核，Ubuntu 2.6.32-36-generic。pthread_getconcurrency为0，set以后返回值正确；再次get也是正确的。程序执行还是单线程执行。
看网上说，多核涉及到绑定CPU，不是很理解。我的是单核，应该不存在绑定CPU的问题。哪位大侠科普一下

#include <stdio.h>

#include <pthread.h>

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <sched.h>



#define MAXITEMS	100*10000

#define MAXTHREADS	100

#define min(a, b)  a<b?a:b



int nitems;

struct {

	pthread_mutex_t mutex;

	int buff[MAXITEMS];

	int nput;

	int nval;

}shared = {PTHREAD_MUTEX_INITIALIZER};

void *producer(void*), *consumer(void*);





struct Node{

	int count;

	int num;

};



int main(int argc, char **argv)

{

	int i, nthreads;

	struct Node count[MAXTHREADS];



	pthread_t tid_producer[MAXTHREADS], tid_consumer;



	if(argc != 3)

		printf("usage: %s items threads!\n", argv[0]),exit(0);





	nitems = min(atoi(argv[1]), MAXITEMS);	

	nthreads = min(atoi(argv[2]), MAXTHREADS);

	printf("nitems=%d, nthreads=%d\n", nitems, nthreads);





	//for more CPUS, must bind to one cpu 

	int level = pthread_getconcurrency();

	printf("getconcurrency = %d\n", level);



	if(pthread_setconcurrency(nthreads) != 0)

		printf("setconcurrency error:%d,%s\n", errno, strerror(errno)), exit(0);

	else{

		level = pthread_getconcurrency(nthreads);

		printf("after set=%d, getconcurrency = %d\n", nthreads, level);

	}







	for(i=0;i<nthreads;++i){

		count[i].num = i;

		count[i].count = 0;

		if(pthread_create(&tid_producer[i], NULL, producer, &count[i]) != 0)

			printf("create pthread %d error: %d,%s\n", i, errno, strerror(errno)), exit(0);

	}



	for(i=0;i<nthreads;++i){

		pthread_join(tid_producer[i], NULL);

		printf("[%d]  num[%d] = %d\n", i, count[i].num, count[i].count);

	}





	pthread_create(&tid_consumer, NULL, consumer, NULL);

	pthread_join(tid_consumer, NULL);



//	sleep(100);



	return 0;

}





void* producer(void *arg)

{

	pthread_t pid = pthread_self();

//	printf("create pthread %x, val=%d\n", (unsigned int)arg, *(int*)arg);

//	sleep(1);

	struct Node *p = (struct Node*)arg;

	printf("num[%d] = %d\n",  p->num, p->count);

	while(1){

		pthread_mutex_lock(&shared.mutex);

		if(shared.nput >= nitems){

			pthread_mutex_unlock(&shared.mutex);

			return NULL;

		}



		shared.buff[shared.nput] = shared.nval;

		++shared.nput;

		++shared.nval;

//	printf("running pthread %x\n", (unsigned int)arg);

		pthread_mutex_unlock(&shared.mutex);

		p->count++;	

	}



}





void* consumer(void* arg)

{

	int i;

	for(i=0;i<nitems;++i){

		if(shared.buff[i] != i)

			printf("buff[%d] = %d\n", i, shared.buff[i]);

	}



	return NULL;

}