[I/OAT]: Add a sysctl for tuning the I/OAT offloaded I/O threshold

Any socket recv of less than this ammount will not be offloaded

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 16 insertions, 0 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 76eaeff76f82..cd9e7c0825ad 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -403,6 +403,7 @@ enum
         NET_TCP_MTU_PROBING=113,
         NET_TCP_BASE_MSS=114,
         NET_IPV4_TCP_WORKAROUND_SIGNED_WINDOWS=115,
+        NET_TCP_DMA_COPYBREAK=116,
 };
 
 enum {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 578cccf275d3..f1f472746e6c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -219,6 +219,7 @@ extern int sysctl_tcp_adv_win_scale;
 extern int sysctl_tcp_tw_reuse;
 extern int sysctl_tcp_frto;
 extern int sysctl_tcp_low_latency;
+extern int sysctl_tcp_dma_copybreak;
 extern int sysctl_tcp_nometrics_save;
 extern int sysctl_tcp_moderate_rcvbuf;
 extern int sysctl_tcp_tso_win_divisor;
diff --git a/net/core/user_dma.c b/net/core/user_dma.c
index 9eee91bcbf3f..b7c98dbcdb81 100644
--- a/net/core/user_dma.c
+++ b/net/core/user_dma.c
@@ -30,6 +30,10 @@
 #include <linux/rtnetlink.h> /* for BUG_TRAP */
 #include <net/tcp.h>
 
+#define NET_DMA_DEFAULT_COPYBREAK 4096
+
+int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;
+
 /**
  *      dma_skb_copy_datagram_iovec - Copy a datagram to an iovec.
  *      @skb - buffer to copy
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 6b6c3adfcf00..6a6aa537b7aa 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -688,6 +688,16 @@ ctl_table ipv4_table[] = {
                 .mode           = 0644,
                 .proc_handler   = &proc_dointvec
         },
+#ifdef CONFIG_NET_DMA
+        {
+                .ctl_name       = NET_TCP_DMA_COPYBREAK,
+                .procname       = "tcp_dma_copybreak",
+                .data           = &sysctl_tcp_dma_copybreak,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec
+        },
+#endif
         { .ctl_name = 0 }
 };