On 4/9/25 10:32 AM, Jeff Layton wrote:
> Currently, this tracepoint displays "wakeup-us", which is the time that
> the woken thread spent sleeping, before dequeueing the next xprt. Add a
> new statistic that shows how long the xprt sat on the queue before being
> serviced.
I don't understand the difference between "waiting on queue" and
"sleeping". When are those two latency measurements not the same?
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> include/linux/sunrpc/svc_xprt.h | 1 +
> include/trace/events/sunrpc.h | 13 +++++++------
> net/sunrpc/svc_xprt.c | 1 +
> 3 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
> index 72be609525796792274d5b8cb5ff37f73723fc23..369a89aea18618748607ee943247c327bf62c8d5 100644
> --- a/include/linux/sunrpc/svc_xprt.h
> +++ b/include/linux/sunrpc/svc_xprt.h
> @@ -53,6 +53,7 @@ struct svc_xprt {
> struct svc_xprt_class *xpt_class;
> const struct svc_xprt_ops *xpt_ops;
> struct kref xpt_ref;
> + ktime_t xpt_qtime;
> struct list_head xpt_list;
> struct lwq_node xpt_ready;
> unsigned long xpt_flags;
> diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
> index 5d331383047b79b9f6dcd699c87287453c1a5f49..b5a0f0bc1a3b7cfd90ce0181a8a419db810988bb 100644
> --- a/include/trace/events/sunrpc.h
> +++ b/include/trace/events/sunrpc.h
> @@ -2040,19 +2040,20 @@ TRACE_EVENT(svc_xprt_dequeue,
>
> TP_STRUCT__entry(
> SVC_XPRT_ENDPOINT_FIELDS(rqst->rq_xprt)
> -
> __field(unsigned long, wakeup)
> + __field(unsigned long, qtime)
> ),
>
> TP_fast_assign(
> - SVC_XPRT_ENDPOINT_ASSIGNMENTS(rqst->rq_xprt);
> + ktime_t ktime = ktime_get();
>
> - __entry->wakeup = ktime_to_us(ktime_sub(ktime_get(),
> - rqst->rq_qtime));
> + SVC_XPRT_ENDPOINT_ASSIGNMENTS(rqst->rq_xprt);
> + __entry->wakeup = ktime_to_us(ktime_sub(ktime, rqst->rq_qtime));
> + __entry->qtime = ktime_to_us(ktime_sub(ktime, rqst->rq_xprt->xpt_qtime));
> ),
>
> - TP_printk(SVC_XPRT_ENDPOINT_FORMAT " wakeup-us=%lu",
> - SVC_XPRT_ENDPOINT_VARARGS, __entry->wakeup)
> + TP_printk(SVC_XPRT_ENDPOINT_FORMAT " wakeup-us=%lu qtime=%lu",
> + SVC_XPRT_ENDPOINT_VARARGS, __entry->wakeup, __entry->qtime)
> );
>
> DECLARE_EVENT_CLASS(svc_xprt_event,
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index ae25405d8bd22672a361d1fd3adfdcebb403f90f..32018557797b1f683d8b7259f5fccd029aebcd71 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -488,6 +488,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
> pool = svc_pool_for_cpu(xprt->xpt_server);
>
> percpu_counter_inc(&pool->sp_sockets_queued);
> + xprt->xpt_qtime = ktime_get();
> lwq_enqueue(&xprt->xpt_ready, &pool->sp_xprts);
>
> svc_pool_wake_idle_thread(pool);
>
--
Chuck Lever
