[PATCH v4 net-next 2/4] tcp: add TCP support for low latency receive poll.

Eliezer Tamir
2013-05-21T14:27:08Z

adds busy-poll support for TCP.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

net/ipv4/tcp.c | 9 +++++++++
net/ipv4/tcp_input.c | 4 ++++
2 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index dcb116d..b9cc512 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -279,6 +279,7 @@

#include <asm/uaccess.h>
#include <asm/ioctls.h>
+#include <net/ll_poll.h>

int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;

@@ -1504,6 +1505,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
if (offset + 1 != skb->len)
continue;
}
+ sk_mark_ll(sk, skb);
if (tcp_hdr(skb)->fin) {
sk_eat_skb(sk, skb, false);
++seq;
@@ -1551,6 +1553,12 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
struct sk_buff *skb;
u32 urg_hole = 0;

+#ifdef CONFIG_INET_LL_RX_POLL
+ if (sk_valid_ll(sk) && skb_queue_empty(&sk->sk_receive_queue)
+ && (sk->sk_state == TCP_ESTABLISHED))
+ sk_poll_ll(sk, nonblock);
+#endif
+
lock_sock(sk);

err = -ENOTCONN;
@@ -1855,6 +1863,7 @@ do_prequeue:
break;
}
}
+ sk_mark_ll(sk, skb);
}

*seq += used;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b358e8c..f3f293b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -74,6 +74,7 @@
#include <linux/ipsec.h>
#include <asm/unaligned.h>
#include <net/netdma.h>
+#include <net/ll_poll.h>

int sysctl_tcp_timestamps __read_mostly = 1;
int sysctl_tcp_window_scaling __read_mostly = 1;
@@ -4329,6 +4330,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
tp->copied_seq += chunk;
eaten = (chunk == skb->len);
tcp_rcv_space_adjust(sk);
+ sk_mark_ll(sk, skb);
}
local_bh_disable();
}
@@ -4896,6 +4898,7 @@ static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
tp->ucopy.len -= chunk;
tp->copied_seq += chunk;
tcp_rcv_space_adjust(sk);
+ sk_mark_ll(sk, skb);
}

local_bh_disable();
@@ -4955,6 +4958,7 @@ static bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
tp->ucopy.len -= chunk;
tp->copied_seq += chunk;
tcp_rcv_space_adjust(sk);
+ sk_mark_ll(sk, skb);

if ((tp->ucopy.len == 0) ||
(tcp_flag_word(tcp_hdr(skb)) & TCP_FLAG_PSH) ||