At 04:03 AM 6/11/2008, Peter Leckie wrote:
>That's a good point you raise there I was looking to closely at the tcp
>equivalent, the correct fix for this issue would be to implement a timer
>function for NFS/RDMA pretty much identical to xs_udp_timer(), as follows:
Hmm, in fact that runs into a different issue - retransmitting over RDMA
isn't allowed, since it consumes server credits and therefore will eventually
overrun the connection's receive queue. I have a patch in my queue to
force a disconnect in fact, which is the appropriate action. I will send them
out soon, it's in with some other post-Connectathon work.
I think with your earlier patch to avoid the 5-second pause, the disconnect
action will be prompt and accurate. However, I would still be concerned why
the RPC was timing out in the first place. Was there an issue in the server?
Tom.
>
>
>Implement xprt_rdma_timer() to be called when an RPC times out.
>This is needed to decrement the cong after an rpc times out preventing
>the congestion aviodance from tripping under retransmitts.
>
>Signed-off-by: Peter Leckie <pleckie@xxxxxxxxxxxxxxxxx>
>Reviewed-by: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>
>---
>
>Index: linux-2.6.25.3/net/sunrpc/xprtrdma/transport.c
>===================================================================
>--- linux-2.6.25.3.orig/net/sunrpc/xprtrdma/transport.c
>+++ linux-2.6.25.3/net/sunrpc/xprtrdma/transport.c
>@@ -450,6 +450,18 @@ out1:
> }
>
> /*
>+ * xprt_rdma_timer - called when a retransmit timeout occurs on a RDMA
>transport
>+ * @task: task that timed out
>+ *
>+ * Adjust the congestion window after a retransmit timeout has occurred.
>+ */
>+static void
>+xprt_rdma_timer(struct rpc_task *task)
>+{
>+ xprt_adjust_cwnd(task, -ETIMEDOUT);
>+}
>+
>+/*
> * Close a connection, during shutdown or timeout/reconnect
> */
> static void
>@@ -755,7 +767,8 @@ static struct rpc_xprt_ops xprt_rdma_pro
> .send_request = xprt_rdma_send_request,
> .close = xprt_rdma_close,
> .destroy = xprt_rdma_destroy,
>- .print_stats = xprt_rdma_print_stats
>+ .print_stats = xprt_rdma_print_stats,
>+ .timer = xprt_rdma_timer
> };
>
> static struct xprt_class xprt_rdma = {
>
>
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