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在网口bond的时候如何选择slave呢？这可以从下面的函数看出static struct slave *bond_find_best_slave(struct bonding *bond){	struct slave *slave, *bestslave = NULL;	struct list_head *iter;	int mintime = bond->params.updelay;#这个函数决定继续用当前的slave还是切换slave	slave = bond_choose_primary_or_current(bond);	if (slave)		return slave;#如果前面没有决定的话，则遍历bond中的slave，选择第一个link up的slave	bond_for_each_slave(bond, slave, iter) {		if (slave->link == BOND_LINK_UP)			return slave;		if (slave->link == BOND_LINK_BACK && bond_slave_is_up(slave) &&		    slave->delay < mintime) {			mintime = slave->delay;			bestslave = slave;		}	}	return bestslave;}重点看一下bond_choose_primary_or_currentstatic struct slave *bond_choose_primary_or_current(struct bonding *bond){	struct slave *prim = rtnl_dereference(bond->primary_slave);	struct slave *curr = rtnl_dereference(bond->curr_active_slave);	if (!prim || prim->link != BOND_LINK_UP) {		if (!curr || curr->link != BOND_LINK_UP)			return NULL;		return curr;	}	if (bond->force_primary) {		bond->force_primary = false;		return prim;	}	if (!curr || curr->link != BOND_LINK_UP)		return prim;#正常情况下可以看到选择slave主要有三种方式	/* At this point, prim and curr are both up */	switch (bond->params.primary_reselect) {#每次有包来的时候都切换，具体这里就从curr切换到prim	case BOND_PRI_RESELECT_ALWAYS:		return prim;#选择速度快的，如果速度是一样的话，则选择全双工的	case BOND_PRI_RESELECT_BETTER:		if (prim->speed < curr->speed)			return curr;		if (prim->speed == curr->speed && prim->duplex <= curr->duplex)			return curr;		return prim;#一直用当前的就不切换	case BOND_PRI_RESELECT_FAILURE:		return curr;	default:		netdev_err(bond->dev, "impossible primary_reselect %d\n",			   bond->params.primary_reselect);		return curr;	}}从这里知道决定切换的就是params.primary_reselect这个参数，这个参数也只有三个有效值

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