From 12a804698b29d040b7cdd92e8a44b0e75164dae9 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 25 Aug 2005 16:25:51 -0700 Subject: [PATCH] RPC: expose API for serializing access to RPC transports The next several patches introduce an API that allows transports to choose whether the RPC client provides congestion control or whether the transport itself provides it. The first method we abstract is the one that serializes access to the RPC transport to prevent the bytes from different requests from mingling together. This method provides proper request serialization and the opportunity to prevent new requests from being started because the transport is congested. The normal situation is for the transport to handle congestion control itself. Although NFS over UDP was first, it has been recognized after years of experience that having the transport provide congestion control is much better than doing it in the RPC client. Thus TCP, and probably every future transport implementation, will use the default method, xprt_lock_write, provided in xprt.c, which does not provide any kind of congestion control. UDP can continue using the xprt.c-provided Van Jacobson congestion avoidance implementation. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- include/linux/sunrpc/xprt.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/sunrpc/xprt.h') diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index ac08e99a81c..eee1c687785 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -132,6 +132,7 @@ struct rpc_xprt; struct rpc_xprt_ops { void (*set_buffer_size)(struct rpc_xprt *xprt); + int (*reserve_xprt)(struct rpc_task *task); void (*connect)(struct rpc_task *task); int (*send_request)(struct rpc_task *task); void (*set_retrans_timeout)(struct rpc_task *task); @@ -232,6 +233,8 @@ void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long */ void xprt_connect(struct rpc_task *task); void xprt_reserve(struct rpc_task *task); +int xprt_reserve_xprt(struct rpc_task *task); +int xprt_reserve_xprt_cong(struct rpc_task *task); int xprt_prepare_transmit(struct rpc_task *task); void xprt_transmit(struct rpc_task *task); int xprt_adjust_timeout(struct rpc_rqst *req); -- cgit v1.2.3