Commit 10014209 authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust
Browse files

xprtrdma: Avoid 250 ms delay on backlog wakeup 



Commit a7210354 ("SUNRPC/xprt: async tasks mustn't block waiting
for memory") changed xprt_rdma_alloc_slot() to set tk_status to
-ENOMEM so that call_reserveresult() would sleep HZ/4 before
retrying.  That rationale applies to xprt_dynamic_alloc_slot(),
where an immediate retry under memory pressure wastes CPU, but not
to the RDMA backlog path: a task woken from the backlog has a slot
waiting for it, so the 250 ms rpc_delay adds latency without
benefit.

This also aligns the code with the existing kernel-doc for
xprt_rdma_alloc_slot(), which already documented %-EAGAIN.

Fixes: a7210354 ("SUNRPC/xprt: async tasks mustn't block waiting for memory")
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 24297c7c

net/sunrpc/xprtrdma/transport.c

+1 −1
Original line number Diff line number Diff line
@@ -510,7 +510,7 @@ xprt_rdma_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task) 
	return;



out_sleep:

	task->tk_status = -ENOMEM;

	task->tk_status = -EAGAIN;

	xprt_add_backlog(xprt, task);

}