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Subject[net-next][PATCH 17/18] RDS: add receive message trace used by application
Date
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>
---
include/uapi/linux/rds.h | 33 +++++++++++++++++++++++++++++++++
net/rds/af_rds.c | 28 ++++++++++++++++++++++++++++
net/rds/ib_recv.c | 4 ++++
net/rds/rds.h | 10 ++++++++++
net/rds/recv.c | 32 +++++++++++++++++++++++++++++---
net/rds/tcp_recv.c | 5 +++++
6 files changed, 109 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/rds.h b/include/uapi/linux/rds.h
index 0f9265c..3833113 100644
--- 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..fd821740 100644
--- 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
--- 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
--- 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
--- 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
--- 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();
}
}

--
1.9.1
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