From 18c64378ad85ef00e70f196793ee8901a8aa2fa1 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 11 Apr 2025 10:22:14 -0400 Subject: sunrpc: add info about xprt queue times to svc_xprt_dequeue tracepoint I've been looking at a problem where we see increased RPC timeouts in clients when the nfs_layout_flexfiles dataserver_timeo value is tuned very low (6s). This is necessary to ensure quick failover to a different mirror if a server goes down, but it causes a lot more major RPC timeouts. Ultimately, the problem is server-side however. It's sometimes doesn't respond to connection attempts. My theory is that the interrupt handler runs when a connection comes in, the xprt ends up being enqueued, but it takes a significant amount of time for the nfsd thread to pick it up. Currently, the svc_xprt_dequeue tracepoint displays "wakeup-us". This is the time between the wake_up() call, and the thread dequeueing the xprt. If no thread was woken, or the thread ended up picking up a different xprt than intended, then this value won't tell us how long the xprt was waiting. Add a new xpt_qtime field to struct svc_xprt and set it in svc_xprt_enqueue(). When the dequeue tracepoint fires, also store the time that the xprt sat on the queue in total. Display it as "qtime-us". Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc_xprt.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sunrpc') diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index 72be60952579..369a89aea186 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; -- cgit v1.2.3