申请和device不再同一个numa节点的memory

如下所示device结构体有一个numa_node 表示当前device所在的numa节点。struct device {struct device*parent;struct device_private*p;struct kobject kobj;const char*init_name; /* initial name of the device */const struct device_type *type;#ifdef CONFIG_NUMAintnuma_node;/* NUMA node this device is close to */#endif}因此一般通过dma_zalloc_coherent等函数申请memory的时候也就会在这个numa节点上申请内存，但是有时候当前节点没有足够的内存，就可以制定和device不同的节点来申请内存.如下例所示：通过dma_zalloc_coherent 申请的memory就和当前device 不再同一个numa节点上static void *mlx5_dma_zalloc_coherent_node(struct mlx5_core_dev *dev,   size_t size, dma_addr_t *dma_handle,   int node){struct mlx5_priv *priv = &dev->priv;int original_node;void *cpu_handle;mutex_lock(&priv->alloc_mutex);//通过dev_to_node的到当前的numa节点并保存到original_nodeoriginal_node = dev_to_node(&dev->pdev->dev);//设置要申请numa节点set_dev_node(&dev->pdev->dev, node);cpu_handle = dma_zalloc_coherent(&dev->pdev->dev, size, dma_handle, GFP_KERNEL);//restore原本的numa节点set_dev_node(&dev->pdev->dev, original_node);mutex_unlock(&priv->alloc_mutex);return cpu_handle;}其中dev_to_node和set_dev_node的源码如下，可见就是操作#ifdef CONFIG_NUMAstatic inline int dev_to_node(struct device *dev){return dev->numa_node;}static inline void set_dev_node(struct device *dev, int node){dev->numa_node = node;}#elsestatic inline int dev_to_node(struct device *dev){return -1;}static inline void set_dev_node(struct device *dev, int node){}#endif