RDS: add receive message trace used by application

Socket option to tap receive path latency in various stages
in nano seconds. It can be enabled on selective sockets using
using SO_RDS_MSG_RXPATH_LATENCY socket option. RDS will return
the data to application with RDS_CMSG_RXPATH_LATENCY in defined
format. Scope is left to add more trace points for future
without need of change in the interface.

Reviewed-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
index ad4892e97f91..e006ef8e6d40 100644
--- a/net/rds/tcp_recv.c
+++ b/net/rds/tcp_recv.c
@@ -180,6 +180,9 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
                         rdsdebug("alloced tinc %p\n", tinc);
                         rds_inc_path_init(&tinc->ti_inc, cp,
                                           cp->cp_conn->c_faddr);
+                        tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] =
+                                        local_clock();
+
                         /*
                          * XXX * we might be able to use the __ variants when
                          * we've already serialized at a higher level.
@@ -204,6 +207,8 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
                                 /* could be 0 for a 0 len message */
                                 tc->t_tinc_data_rem =
                                         be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
+                                tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_START] =
+                                        local_clock();
                         }
                 }