mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-02-19 15:57:56 -05:00
18c64378ad
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 <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>