SUNRPC: introduce per-task RPC iostats

Account for various things that occur while an RPC task is executed.
Separate timers for RPC round trip and RPC execution time show how
long RPC requests wait in queue before being sent.  Eventually these
will be accumulated at xprt_release time in one place where they can
be viewed from userland.

Test plan:
Compile kernel with CONFIG_NFS enabled.

Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 93a0a3ca0d5f..c6241976a6ee 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -648,6 +648,8 @@ void xprt_complete_rqst(struct rpc_task *task, int copied)
                         task->tk_pid, ntohl(req->rq_xid), copied);
 
         task->tk_xprt->stat.recvs++;
+        task->tk_rtt = (long)jiffies - req->rq_xtime;
+
         list_del_init(&req->rq_list);
         req->rq_received = req->rq_private_buf.len = copied;
         rpc_wake_up_task(task);