SUNRPC: track length of RPC wait queues

RPC wait queue length will eventually be exported to userland via the RPC
iostats interface.

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>

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index a390c9b..6c23f73 100644 (file)
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -203,6 +203,7 @@ struct rpc_wait_queue {
        unsigned char           priority;               /* current priority */
        unsigned char           count;                  /* # task groups remaining serviced so far */
        unsigned char           nr;                     /* # tasks remaining for cookie */
+       unsigned short          qlen;                   /* total # tasks waiting in queue */
 #ifdef RPC_DEBUG
        const char *            name;
 #endif

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 1b74420..aa0449d 100644 (file)
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -181,6 +181,7 @@ static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *
        else
                list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
        task->u.tk_wait.rpc_waitq = queue;
+       queue->qlen++;
        rpc_set_queued(task);
 
        dprintk("RPC: %4d added to queue %p \"%s\"\n",
@@ -215,6 +216,7 @@ static void __rpc_remove_wait_queue(struct rpc_task *task)
                __rpc_remove_wait_queue_priority(task);
        else
                list_del(&task->u.tk_wait.list);
+       queue->qlen--;
        dprintk("RPC: %4d removed from queue %p \"%s\"\n",
                                task->tk_pid, queue, rpc_qname(queue));
 }