svc: Report xprt dequeue latency

Record the time between when a rqstp is enqueued on a transport
and when it is dequeued. This includes how long the rqstp waits on
the queue and how long it takes the kernel scheduler to wake a
nfsd thread to service it.

The svc_xprt_dequeue trace point is altered to include the number
of microseconds between xprt_enqueue and xprt_dequeue.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 3bd7504..dc4c009 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -272,6 +272,7 @@ struct svc_rqst {
 #define        RQ_BUSY         (6)                     /* request is busy */
 #define        RQ_DATA         (7)                     /* request has data */
        unsigned long           rq_flags;       /* flags field */
+       ktime_t                 rq_qtime;       /* enqueue time */
 
        void *                  rq_argp;        /* decoded arguments */
        void *                  rq_resp;        /* xdr'd results */

diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 1b383f7..922cb89 100644 (file)
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -657,14 +657,36 @@ DECLARE_EVENT_CLASS(svc_xprt_event,
                        show_svc_xprt_flags(__entry->flags))
 );
 
-DEFINE_EVENT(svc_xprt_event, svc_xprt_dequeue,
-       TP_PROTO(struct svc_xprt *xprt),
-       TP_ARGS(xprt));
-
 DEFINE_EVENT(svc_xprt_event, svc_xprt_no_write_space,
        TP_PROTO(struct svc_xprt *xprt),
        TP_ARGS(xprt));
 
+TRACE_EVENT(svc_xprt_dequeue,
+       TP_PROTO(struct svc_rqst *rqst),
+
+       TP_ARGS(rqst),
+
+       TP_STRUCT__entry(
+               __field(struct svc_xprt *, xprt)
+               __field(unsigned long, flags)
+               __field(unsigned long, wakeup)
+               __string(addr, rqst->rq_xprt->xpt_remotebuf)
+       ),
+
+       TP_fast_assign(
+               __entry->xprt = rqst->rq_xprt;
+               __entry->flags = rqst->rq_xprt->xpt_flags;
+               __entry->wakeup = ktime_to_us(ktime_sub(ktime_get(),
+                                                       rqst->rq_qtime));
+               __assign_str(addr, rqst->rq_xprt->xpt_remotebuf);
+       ),
+
+       TP_printk("xprt=%p addr=%s flags=%s wakeup-us=%lu",
+                       __entry->xprt, __get_str(addr),
+                       show_svc_xprt_flags(__entry->flags),
+                       __entry->wakeup)
+);
+
 TRACE_EVENT(svc_wake_up,
        TP_PROTO(int pid),
 

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index a7425da..5185efb 100644 (file)
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -409,6 +409,7 @@ void svc_xprt_do_enqueue(struct svc_xprt *xprt)
                if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags))
                        continue;
                atomic_long_inc(&pool->sp_stats.threads_woken);
+               rqstp->rq_qtime = ktime_get();
                wake_up_process(rqstp->rq_task);
                goto out_unlock;
        }
@@ -530,7 +531,6 @@ void svc_wake_up(struct svc_serv *serv)
                if (test_bit(RQ_BUSY, &rqstp->rq_flags))
                        continue;
                rcu_read_unlock();
-               dprintk("svc: daemon %p woken up.\n", rqstp);
                wake_up_process(rqstp->rq_task);
                trace_svc_wake_up(rqstp->rq_task->pid);
                return;
@@ -726,7 +726,7 @@ out_found:
                rqstp->rq_chandle.thread_wait = 5*HZ;
        else
                rqstp->rq_chandle.thread_wait = 1*HZ;
-       trace_svc_xprt_dequeue(rqstp->rq_xprt);
+       trace_svc_xprt_dequeue(rqstp);
        return rqstp->rq_xprt;
 }