[PATCH v9 net-next 4/7] tcp: add low latency socket poll support.

From: Eliezer Tamir
Date: Wed Jun 05 2013 - 06:34:54 EST


Adds low latency socket poll support for TCP.
In tcp_v[46]_rcv() add a call to sk_mark_ll() to copy the napi_id
from the skb to the sk.
In tcp_recvmsg(), when there is no data in the socket we busy-poll.
This is a good example of how to add busy-poll support to more protocols.

Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
Tested-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: Eliezer Tamir <eliezer.tamir@xxxxxxxxxxxxxxx>
---

net/ipv4/tcp.c | 5 +++++
net/ipv4/tcp_ipv4.c | 2 ++
net/ipv6/tcp_ipv6.c | 2 ++
3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b5d4ad9..bf09f6b 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;

@@ -1553,6 +1554,10 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
struct sk_buff *skb;
u32 urg_hole = 0;

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

err = -ENOTCONN;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d20ede0..35fd8bc 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -75,6 +75,7 @@
#include <net/netdma.h>
#include <net/secure_seq.h>
#include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>

#include <linux/inet.h>
#include <linux/ipv6.h>
@@ -2011,6 +2012,7 @@ process:
if (sk_filter(sk, skb))
goto discard_and_relse;

+ sk_mark_ll(sk, skb);
skb->dev = NULL;

bh_lock_sock_nested(sk);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0a17ed9..5cffa5c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -63,6 +63,7 @@
#include <net/inet_common.h>
#include <net/secure_seq.h>
#include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>

#include <asm/uaccess.h>

@@ -1498,6 +1499,7 @@ process:
if (sk_filter(sk, skb))
goto discard_and_relse;

+ sk_mark_ll(sk, skb);
skb->dev = NULL;

bh_lock_sock_nested(sk);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/