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xen-netback: switch to NAPI + kthread 1:1 model

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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>
This commit is contained in:
Wei Liu
2013-08-26 12:59:38 +01:00
committed by David S. Miller
parent 43e9d19432
commit b3f980bd82
3 changed files with 355 additions and 511 deletions
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136
drivers/net/xen-netback/common.h
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@@ -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 @@ struct xenvif {
/* 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 @@ struct xenvif {
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 @@ static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
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 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
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 @@ int xen_netbk_map_frontend_rings(struct xenvif *vif,
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 @@ void xenvif_carrier_off(struct xenvif *vif);
/* 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__ */