sock: MSG_ZEROCOPY notification coalescing
In the simple case, each sendmsg() call generates data and eventually
a zerocopy ready notification N, where N indicates the Nth successful
invocation of sendmsg() with the MSG_ZEROCOPY flag on this socket.
TCP and corked sockets can cause send() calls to append new data to an
existing sk_buff and, thus, ubuf_info. In that case the notification
must hold a range. odify ubuf_info to store a inclusive range [N..N+m]
and add skb_zerocopy_realloc() to optionally extend an existing range.
Also coalesce notifications in this common case: if a notification
[1, 1] is about to be queued while [0, 0] is the queue tail, just modify
the head of the queue to read [0, 1].
Coalescing is limited to a few TSO frames worth of data to bound
notification latency.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e538793..f5bdd93 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -444,15 +444,26 @@ enum {
*/
struct ubuf_info {
void (*callback)(struct ubuf_info *, bool zerocopy_success);
- void *ctx;
- unsigned long desc;
- u16 zerocopy:1;
+ union {
+ struct {
+ unsigned long desc;
+ void *ctx;
+ };
+ struct {
+ u32 id;
+ u16 len;
+ u16 zerocopy:1;
+ u32 bytelen;
+ };
+ };
atomic_t refcnt;
};
#define skb_uarg(SKB) ((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))
struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size);
+struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
+ struct ubuf_info *uarg);
static inline void sock_zerocopy_get(struct ubuf_info *uarg)
{