本文共 3025 字，大约阅读时间需要 10 分钟。

dpdk中要使用timer 必须分为下面三步第一步：在dpdk中要使用timer，必须初始化RTE timer library其源码分析如下：voidrte_timer_subsystem_init(void){	unsigned lcore_id;	/* since priv_timer is static, it's zeroed by default, so only init some	 * fields.	 */	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id ++) {		rte_spinlock_init(&priv_timer[lcore_id].list_lock);		priv_timer[lcore_id].prev_lcore = lcore_id;	}}可见time子系统初始化是给每一个cpu初始化一个spin lock，并记录当前的cpu id第二步：必须为每个timer的回调函数初始化一个rte_timer结构体voidrte_timer_init(struct rte_timer *tim){	union rte_timer_status status;	status.state = RTE_TIMER_STOP;	status.owner = RTE_TIMER_NO_OWNER;	tim->status.u32 = status.u32;}可以看到只是初始化rte_timer的status 变量第三步：设置timer工作的模式intrte_timer_reset(struct rte_timer *tim, uint64_t ticks,		enum rte_timer_type type, unsigned tim_lcore,		rte_timer_cb_t fct, void *arg){	#得到当前时间	uint64_t cur_time = rte_get_timer_cycles();	uint64_t period;	if (unlikely((tim_lcore != (unsigned)LCORE_ID_ANY) &&			!(rte_lcore_is_enabled(tim_lcore) ||			  rte_lcore_has_role(tim_lcore, ROLE_SERVICE) == 0)))		return -1;	#如果type是PERIODICAL，说明是周期timer，这里就要设置timer的周期，否则周期就是零	if (type == PERIODICAL)		period = ticks;	else		period = 0;	#获得当前时间和周期后继续设置timer	return __rte_timer_reset(tim,  cur_time + ticks, period, tim_lcore,			  fct, arg, 0);}static int__rte_timer_reset(struct rte_timer *tim, uint64_t expire,		  uint64_t period, unsigned tim_lcore,		  rte_timer_cb_t fct, void *arg,		  int local_is_locked){	union rte_timer_status prev_status, status;	int ret;	#获得当前cpu id	unsigned lcore_id = rte_lcore_id();	/* round robin for tim_lcore */	#这里检查timer是否可以建立在其他core上	if (tim_lcore == (unsigned)LCORE_ID_ANY) {		if (lcore_id < RTE_MAX_LCORE) {			/* EAL thread with valid lcore_id */			tim_lcore = rte_get_next_lcore(				priv_timer[lcore_id].prev_lcore,				0, 1);			priv_timer[lcore_id].prev_lcore = tim_lcore;		} else			/* non-EAL thread do not run rte_timer_manage(),			 * so schedule the timer on the first enabled lcore. */			tim_lcore = rte_get_next_lcore(LCORE_ID_ANY, 0, 1);	}	/* wait that the timer is in correct status before update,	 * and mark it as being configured */	#只是timer状态	ret = timer_set_config_state(tim, &prev_status);	if (ret < 0)		return -1;	#用于debug函数，release版本为空函数	__TIMER_STAT_ADD(reset, 1);	#如果timer已经在运行状态说明这次是要update状态	if (prev_status.state == RTE_TIMER_RUNNING &&	    lcore_id < RTE_MAX_LCORE) {		priv_timer[lcore_id].updated = 1;	}	/* remove it from list */	#如果timer是pending的，则调用timer_del删除timer	if (prev_status.state == RTE_TIMER_PENDING) {		timer_del(tim, prev_status, local_is_locked);		__TIMER_STAT_ADD(pending, -1);	}	#设置time的周期，下次到期时间，回调函数，以及参数	tim->period = period;	tim->expire = expire;	tim->f = fct;	tim->arg = arg;	#debug函数，打印状态	__TIMER_STAT_ADD(pending, 1);	#添加这个timer后，这个timer就开始正常工作了	timer_add(tim, tim_lcore, local_is_locked);	/* update state: as we are in CONFIG state, only us can modify	 * the state so we don't need to use cmpset() here */	rte_wmb();		status.state = RTE_TIMER_PENDING;	status.owner = (int16_t)tim_lcore;	tim->status.u32 = status.u32;	return 0;}

转载地址：http://cnnmi.baihongyu.com/