xen-netback: switch to NAPI + kthread 1:1 model
This patch implements 1:1 model netback. NAPI and kthread are utilized
to do the weight-lifting job:
- NAPI is used for guest side TX (host side RX)
- kthread is used for guest side RX (host side TX)
Xenvif and xen_netbk are made into one structure to reduce code size.
This model provides better scheduling fairness among vifs. It is also
prerequisite for implementing multiqueue for Xen netback.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 8a4d77e..9c1f158 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -45,31 +45,109 @@
#include <xen/grant_table.h>
#include <xen/xenbus.h>
-struct xen_netbk;
+typedef unsigned int pending_ring_idx_t;
+#define INVALID_PENDING_RING_IDX (~0U)
+
+/* For the head field in pending_tx_info: it is used to indicate
+ * whether this tx info is the head of one or more coalesced requests.
+ *
+ * When head != INVALID_PENDING_RING_IDX, it means the start of a new
+ * tx requests queue and the end of previous queue.
+ *
+ * An example sequence of head fields (I = INVALID_PENDING_RING_IDX):
+ *
+ * ...|0 I I I|5 I|9 I I I|...
+ * -->|<-INUSE----------------
+ *
+ * After consuming the first slot(s) we have:
+ *
+ * ...|V V V V|5 I|9 I I I|...
+ * -----FREE->|<-INUSE--------
+ *
+ * where V stands for "valid pending ring index". Any number other
+ * than INVALID_PENDING_RING_IDX is OK. These entries are considered
+ * free and can contain any number other than
+ * INVALID_PENDING_RING_IDX. In practice we use 0.
+ *
+ * The in use non-INVALID_PENDING_RING_IDX (say 0, 5 and 9 in the
+ * above example) number is the index into pending_tx_info and
+ * mmap_pages arrays.
+ */
+struct pending_tx_info {
+ struct xen_netif_tx_request req; /* coalesced tx request */
+ pending_ring_idx_t head; /* head != INVALID_PENDING_RING_IDX
+ * if it is head of one or more tx
+ * reqs
+ */
+};
+
+#define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, PAGE_SIZE)
+#define XEN_NETIF_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, PAGE_SIZE)
+
+struct xenvif_rx_meta {
+ int id;
+ int size;
+ int gso_size;
+};
+
+/* Discriminate from any valid pending_idx value. */
+#define INVALID_PENDING_IDX 0xFFFF
+
+#define MAX_BUFFER_OFFSET PAGE_SIZE
+
+#define MAX_PENDING_REQS 256
struct xenvif {
/* Unique identifier for this interface. */
domid_t domid;
unsigned int handle;
- /* Reference to netback processing backend. */
- struct xen_netbk *netbk;
-
- u8 fe_dev_addr[6];
-
+ /* Use NAPI for guest TX */
+ struct napi_struct napi;
/* When feature-split-event-channels = 0, tx_irq = rx_irq. */
unsigned int tx_irq;
- unsigned int rx_irq;
/* Only used when feature-split-event-channels = 1 */
char tx_irq_name[IFNAMSIZ+4]; /* DEVNAME-tx */
- char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */
-
- /* List of frontends to notify after a batch of frames sent. */
- struct list_head notify_list;
-
- /* The shared rings and indexes. */
struct xen_netif_tx_back_ring tx;
+ struct sk_buff_head tx_queue;
+ struct page *mmap_pages[MAX_PENDING_REQS];
+ pending_ring_idx_t pending_prod;
+ pending_ring_idx_t pending_cons;
+ u16 pending_ring[MAX_PENDING_REQS];
+ struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
+
+ /* Coalescing tx requests before copying makes number of grant
+ * copy ops greater or equal to number of slots required. In
+ * worst case a tx request consumes 2 gnttab_copy.
+ */
+ struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
+
+
+ /* Use kthread for guest RX */
+ struct task_struct *task;
+ wait_queue_head_t wq;
+ /* When feature-split-event-channels = 0, tx_irq = rx_irq. */
+ unsigned int rx_irq;
+ /* Only used when feature-split-event-channels = 1 */
+ char rx_irq_name[IFNAMSIZ+4]; /* DEVNAME-rx */
struct xen_netif_rx_back_ring rx;
+ struct sk_buff_head rx_queue;
+
+ /* Allow xenvif_start_xmit() to peek ahead in the rx request
+ * ring. This is a prediction of what rx_req_cons will be
+ * once all queued skbs are put on the ring.
+ */
+ RING_IDX rx_req_cons_peek;
+
+ /* Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
+ * head/fragment page uses 2 copy operations because it
+ * straddles two buffers in the frontend.
+ */
+ struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
+ struct xenvif_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
+
+
+ u8 fe_dev_addr[6];
/* Frontend feature information. */
u8 can_sg:1;
@@ -80,13 +158,6 @@
/* Internal feature information. */
u8 can_queue:1; /* can queue packets for receiver? */
- /*
- * Allow xenvif_start_xmit() to peek ahead in the rx request
- * ring. This is a prediction of what rx_req_cons will be
- * once all queued skbs are put on the ring.
- */
- RING_IDX rx_req_cons_peek;
-
/* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
unsigned long credit_bytes;
unsigned long credit_usec;
@@ -97,11 +168,7 @@
unsigned long rx_gso_checksum_fixup;
/* Miscellaneous private stuff. */
- struct list_head schedule_list;
- atomic_t refcnt;
struct net_device *dev;
-
- wait_queue_head_t waiting_to_free;
};
static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
@@ -109,9 +176,6 @@
return to_xenbus_device(vif->dev->dev.parent);
}
-#define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, PAGE_SIZE)
-#define XEN_NETIF_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, PAGE_SIZE)
-
struct xenvif *xenvif_alloc(struct device *parent,
domid_t domid,
unsigned int handle);
@@ -121,9 +185,6 @@
unsigned int rx_evtchn);
void xenvif_disconnect(struct xenvif *vif);
-void xenvif_get(struct xenvif *vif);
-void xenvif_put(struct xenvif *vif);
-
int xenvif_xenbus_init(void);
void xenvif_xenbus_fini(void);
@@ -139,18 +200,8 @@
grant_ref_t tx_ring_ref,
grant_ref_t rx_ring_ref);
-/* (De)Register a xenvif with the netback backend. */
-void xen_netbk_add_xenvif(struct xenvif *vif);
-void xen_netbk_remove_xenvif(struct xenvif *vif);
-
-/* (De)Schedule backend processing for a xenvif */
-void xen_netbk_schedule_xenvif(struct xenvif *vif);
-void xen_netbk_deschedule_xenvif(struct xenvif *vif);
-
/* Check for SKBs from frontend and schedule backend processing */
void xen_netbk_check_rx_xenvif(struct xenvif *vif);
-/* Receive an SKB from the frontend */
-void xenvif_receive_skb(struct xenvif *vif, struct sk_buff *skb);
/* Queue an SKB for transmission to the frontend */
void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb);
@@ -163,6 +214,11 @@
/* Returns number of ring slots required to send an skb to the frontend */
unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb);
+int xen_netbk_tx_action(struct xenvif *vif, int budget);
+void xen_netbk_rx_action(struct xenvif *vif);
+
+int xen_netbk_kthread(void *data);
+
extern bool separate_tx_rx_irq;
#endif /* __XEN_NETBACK__COMMON_H__ */