Commit deaa5c96 authored Jan 09, 2019 by Chuck Lever Committed by Anna Schumaker Jan 15, 2019

SUNRPC: Address Kerberos performance/behavior regression



When using Kerberos with v4.20, I've observed frequent connection
loss on heavy workloads. I traced it down to the client underrunning
the GSS sequence number window -- NFS servers are required to drop
the RPC with the low sequence number, and also drop the connection
to signal that an RPC was dropped.

Bisected to commit 918f3c1f ("SUNRPC: Improve latency for
interactive tasks").

I've got a one-line workaround for this issue, which is easy to
backport to v4.20 while a more permanent solution is being derived.
Essentially, tk_owner-based sorting is disabled for RPCs that carry
a GSS sequence number.

Fixes: 918f3c1f ("SUNRPC: Improve latency for interactive ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

parent 97b78ae9

net/sunrpc/xprt.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1178,7 +1178,7 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
		INIT_LIST_HEAD(&req->rq_xmit2);
		goto out;
		}
		} else {
		} else if (!req->rq_seqno) {
		list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
		if (pos->rq_task->tk_owner != task->tk_owner)
		continue;

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