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, 6 insertions, 0 deletions

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index 6c23f73a799..45a64ae963e 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -86,6 +86,12 @@ struct rpc_task {
                 struct work_struct      tk_work;        /* Async task work queue */
                 struct rpc_wait         tk_wait;        /* RPC wait */
         } u;
+
+        unsigned short          tk_timeouts;    /* maj timeouts */
+        size_t                  tk_bytes_sent;  /* total bytes sent */
+        unsigned long           tk_start;       /* RPC task init timestamp */
+        long                    tk_rtt;         /* round-trip time (jiffies) */
+
 #ifdef RPC_DEBUG
         unsigned short          tk_pid;         /* debugging aid */
 #endif