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>

diff --git a/include/uapi/linux/rds.h b/include/uapi/linux/rds.h
index 0f9265c..3833113 100644 (file)
--- a/include/uapi/linux/rds.h
+++ b/include/uapi/linux/rds.h
@@ -52,6 +52,13 @@
 #define RDS_GET_MR_FOR_DEST            7
 #define SO_RDS_TRANSPORT               8
 
+/* Socket option to tap receive path latency
+ *     SO_RDS: SO_RDS_MSG_RXPATH_LATENCY
+ *     Format used struct rds_rx_trace_so
+ */
+#define SO_RDS_MSG_RXPATH_LATENCY      10
+
+
 /* supported values for SO_RDS_TRANSPORT */
 #define        RDS_TRANS_IB    0
 #define        RDS_TRANS_IWARP 1
@@ -77,6 +84,12 @@
  *     the same as for the GET_MR setsockopt.
  * RDS_CMSG_RDMA_STATUS (recvmsg)
  *     Returns the status of a completed RDMA operation.
+ * RDS_CMSG_RXPATH_LATENCY(recvmsg)
+ *     Returns rds message latencies in various stages of receive
+ *     path in nS. Its set per socket using SO_RDS_MSG_RXPATH_LATENCY
+ *     socket option. Legitimate points are defined in
+ *     enum rds_message_rxpath_latency. More points can be added in
+ *     future. CSMG format is struct rds_cmsg_rx_trace.
  */
 #define RDS_CMSG_RDMA_ARGS             1
 #define RDS_CMSG_RDMA_DEST             2
@@ -87,6 +100,7 @@
 #define RDS_CMSG_ATOMIC_CSWP           7
 #define RDS_CMSG_MASKED_ATOMIC_FADD    8
 #define RDS_CMSG_MASKED_ATOMIC_CSWP    9
+#define RDS_CMSG_RXPATH_LATENCY                11
 
 #define RDS_INFO_FIRST                 10000
 #define RDS_INFO_COUNTERS              10000
@@ -171,6 +185,25 @@ struct rds_info_rdma_connection {
        uint32_t        rdma_mr_size;
 };
 
+/* RDS message Receive Path Latency points */
+enum rds_message_rxpath_latency {
+       RDS_MSG_RX_HDR_TO_DGRAM_START = 0,
+       RDS_MSG_RX_DGRAM_REASSEMBLE,
+       RDS_MSG_RX_DGRAM_DELIVERED,
+       RDS_MSG_RX_DGRAM_TRACE_MAX
+};
+
+struct rds_rx_trace_so {
+       u8 rx_traces;
+       u8 rx_trace_pos[RDS_MSG_RX_DGRAM_TRACE_MAX];
+};
+
+struct rds_cmsg_rx_trace {
+       u8 rx_traces;
+       u8 rx_trace_pos[RDS_MSG_RX_DGRAM_TRACE_MAX];
+       u64 rx_trace[RDS_MSG_RX_DGRAM_TRACE_MAX];
+};
+
 /*
  * Congestion monitoring.
  * Congestion control in RDS happens at the host connection

diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index 2ac1e61..fd82174 100644 (file)
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -298,6 +298,30 @@ static int rds_enable_recvtstamp(struct sock *sk, char __user *optval,
        return 0;
 }
 
+static int rds_recv_track_latency(struct rds_sock *rs, char __user *optval,
+                                 int optlen)
+{
+       struct rds_rx_trace_so trace;
+       int i;
+
+       if (optlen != sizeof(struct rds_rx_trace_so))
+               return -EFAULT;
+
+       if (copy_from_user(&trace, optval, sizeof(trace)))
+               return -EFAULT;
+
+       rs->rs_rx_traces = trace.rx_traces;
+       for (i = 0; i < rs->rs_rx_traces; i++) {
+               if (trace.rx_trace_pos[i] > RDS_MSG_RX_DGRAM_TRACE_MAX) {
+                       rs->rs_rx_traces = 0;
+                       return -EFAULT;
+               }
+               rs->rs_rx_trace[i] = trace.rx_trace_pos[i];
+       }
+
+       return 0;
+}
+
 static int rds_setsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, unsigned int optlen)
 {
@@ -338,6 +362,9 @@ static int rds_setsockopt(struct socket *sock, int level, int optname,
                ret = rds_enable_recvtstamp(sock->sk, optval, optlen);
                release_sock(sock->sk);
                break;
+       case SO_RDS_MSG_RXPATH_LATENCY:
+               ret = rds_recv_track_latency(rs, optval, optlen);
+               break;
        default:
                ret = -ENOPROTOOPT;
        }
@@ -484,6 +511,7 @@ static int __rds_create(struct socket *sock, struct sock *sk, int protocol)
        INIT_LIST_HEAD(&rs->rs_cong_list);
        spin_lock_init(&rs->rs_rdma_lock);
        rs->rs_rdma_keys = RB_ROOT;
+       rs->rs_rx_traces = 0;
 
        spin_lock_bh(&rds_sock_lock);
        list_add_tail(&rs->rs_item, &rds_sock_list);

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 4b0f126..e10624a 100644 (file)
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -911,8 +911,12 @@ static void rds_ib_process_recv(struct rds_connection *conn,
                ic->i_ibinc = ibinc;
 
                hdr = &ibinc->ii_inc.i_hdr;
+               ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] =
+                               local_clock();
                memcpy(hdr, ihdr, sizeof(*hdr));
                ic->i_recv_data_rem = be32_to_cpu(hdr->h_len);
+               ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_START] =
+                               local_clock();
 
                rdsdebug("ic %p ibinc %p rem %u flag 0x%x\n", ic, ibinc,
                         ic->i_recv_data_rem, hdr->h_flags);

diff --git a/net/rds/rds.h b/net/rds/rds.h
index f713194..07fff73 100644 (file)
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -253,6 +253,11 @@ struct rds_ext_header_rdma_dest {
 #define RDS_EXTHDR_GEN_NUM     6
 
 #define __RDS_EXTHDR_MAX       16 /* for now */
+#define RDS_RX_MAX_TRACES      (RDS_MSG_RX_DGRAM_TRACE_MAX + 1)
+#define        RDS_MSG_RX_HDR          0
+#define        RDS_MSG_RX_START        1
+#define        RDS_MSG_RX_END          2
+#define        RDS_MSG_RX_CMSG         3
 
 struct rds_incoming {
        atomic_t                i_refcount;
@@ -265,6 +270,7 @@ struct rds_incoming {
 
        rds_rdma_cookie_t       i_rdma_cookie;
        struct timeval          i_rx_tstamp;
+       u64                     i_rx_lat_trace[RDS_RX_MAX_TRACES];
 };
 
 struct rds_mr {
@@ -575,6 +581,10 @@ struct rds_sock {
        unsigned char           rs_recverr,
                                rs_cong_monitor;
        u32                     rs_hash_initval;
+
+       /* Socket receive path trace points*/
+       u8                      rs_rx_traces;
+       u8                      rs_rx_trace[RDS_MSG_RX_DGRAM_TRACE_MAX];
 };
 
 static inline struct rds_sock *rds_sk_to_rs(const struct sock *sk)

diff --git a/net/rds/recv.c b/net/rds/recv.c
index ba19eee..8b7e7b7 100644 (file)
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -43,6 +43,8 @@
 void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
                  __be32 saddr)
 {
+       int i;
+
        atomic_set(&inc->i_refcount, 1);
        INIT_LIST_HEAD(&inc->i_item);
        inc->i_conn = conn;
@@ -50,6 +52,9 @@ void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
        inc->i_rdma_cookie = 0;
        inc->i_rx_tstamp.tv_sec = 0;
        inc->i_rx_tstamp.tv_usec = 0;
+
+       for (i = 0; i < RDS_RX_MAX_TRACES; i++)
+               inc->i_rx_lat_trace[i] = 0;
 }
 EXPORT_SYMBOL_GPL(rds_inc_init);
 
@@ -373,6 +378,7 @@ void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
                if (sock_flag(sk, SOCK_RCVTSTAMP))
                        do_gettimeofday(&inc->i_rx_tstamp);
                rds_inc_addref(inc);
+               inc->i_rx_lat_trace[RDS_MSG_RX_END] = local_clock();
                list_add_tail(&inc->i_item, &rs->rs_recv_queue);
                __rds_wake_sk_sleep(sk);
        } else {
@@ -534,7 +540,7 @@ static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg,
                ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
                                sizeof(inc->i_rdma_cookie), &inc->i_rdma_cookie);
                if (ret)
-                       return ret;
+                       goto out;
        }
 
        if ((inc->i_rx_tstamp.tv_sec != 0) &&
@@ -543,10 +549,30 @@ static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg,
                               sizeof(struct timeval),
                               &inc->i_rx_tstamp);
                if (ret)
-                       return ret;
+                       goto out;
        }
 
-       return 0;
+       if (rs->rs_rx_traces) {
+               struct rds_cmsg_rx_trace t;
+               int i, j;
+
+               inc->i_rx_lat_trace[RDS_MSG_RX_CMSG] = local_clock();
+               t.rx_traces =  rs->rs_rx_traces;
+               for (i = 0; i < rs->rs_rx_traces; i++) {
+                       j = rs->rs_rx_trace[i];
+                       t.rx_trace_pos[i] = j;
+                       t.rx_trace[i] = inc->i_rx_lat_trace[j + 1] -
+                                         inc->i_rx_lat_trace[j];
+               }
+
+               ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RXPATH_LATENCY,
+                              sizeof(t), &t);
+               if (ret)
+                       goto out;
+       }
+
+out:
+       return ret;
 }
 
 int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,

diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
index ad4892e..e006ef8 100644 (file)
--- 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();
                        }
                }