From 46c0ee8bc4ad3743de05e8b8b20201df44dcb6d3 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 25 Aug 2005 16:25:52 -0700 Subject: [PATCH] [PATCH] RPC: separate xprt_timer implementations Allow transports to hook the retransmit timer interrupt. Some transports calculate their congestion window here so that a retransmit timeout has immediate effect on the congestion window. 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 | 2 ++ net/sunrpc/xprt.c | 45 ++++++++++++++++++++------------------------- net/sunrpc/xprtsock.c | 12 ++++++++++++ 3 files changed, 34 insertions(+), 25 deletions(-) diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index 86833b7..443c3f9 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -137,6 +137,7 @@ struct rpc_xprt_ops { void (*connect)(struct rpc_task *task); int (*send_request)(struct rpc_task *task); void (*set_retrans_timeout)(struct rpc_task *task); + void (*timer)(struct rpc_task *task); void (*close)(struct rpc_xprt *xprt); void (*destroy)(struct rpc_xprt *xprt); }; @@ -257,6 +258,7 @@ void xprt_set_retrans_timeout_rtt(struct rpc_task *task); void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status); void xprt_wait_for_buffer_space(struct rpc_task *task); void xprt_write_space(struct rpc_xprt *xprt); +void xprt_adjust_cwnd(struct rpc_task *task, int result); struct rpc_rqst * xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid); void xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied); void xprt_disconnect(struct rpc_xprt *xprt); diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index e92ea99..ffc5955 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -289,16 +289,19 @@ __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req) __xprt_lock_write_next_cong(xprt); } -/* - * Adjust RPC congestion window +/** + * xprt_adjust_cwnd - adjust transport congestion window + * @task: recently completed RPC request used to adjust window + * @result: result code of completed RPC request + * * We use a time-smoothed congestion estimator to avoid heavy oscillation. */ -static void -xprt_adjust_cwnd(struct rpc_xprt *xprt, int result) +void xprt_adjust_cwnd(struct rpc_task *task, int result) { - unsigned long cwnd; + struct rpc_rqst *req = task->tk_rqstp; + struct rpc_xprt *xprt = task->tk_xprt; + unsigned long cwnd = xprt->cwnd; - cwnd = xprt->cwnd; if (result >= 0 && cwnd <= xprt->cong) { /* The (cwnd >> 1) term makes sure * the result gets rounded properly. */ @@ -314,6 +317,7 @@ xprt_adjust_cwnd(struct rpc_xprt *xprt, int result) dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n", xprt->cong, xprt->cwnd, cwnd); xprt->cwnd = cwnd; + __xprt_put_cong(xprt, req); } /** @@ -602,8 +606,7 @@ void xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied) /* Adjust congestion window */ if (!xprt->nocong) { unsigned timer = task->tk_msg.rpc_proc->p_timer; - xprt_adjust_cwnd(xprt, copied); - __xprt_put_cong(xprt, req); + xprt_adjust_cwnd(task, copied); if (timer) { if (req->rq_ntrans == 1) rpc_update_rtt(clnt->cl_rtt, timer, @@ -640,27 +643,19 @@ void xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied) return; } -/* - * RPC receive timeout handler. - */ -static void -xprt_timer(struct rpc_task *task) +static void xprt_timer(struct rpc_task *task) { - struct rpc_rqst *req = task->tk_rqstp; + struct rpc_rqst *req = task->tk_rqstp; struct rpc_xprt *xprt = req->rq_xprt; - spin_lock(&xprt->transport_lock); - if (req->rq_received) - goto out; - - xprt_adjust_cwnd(req->rq_xprt, -ETIMEDOUT); - __xprt_put_cong(xprt, req); + dprintk("RPC: %4d xprt_timer\n", task->tk_pid); - dprintk("RPC: %4d xprt_timer (%s request)\n", - task->tk_pid, req ? "pending" : "backlogged"); - - task->tk_status = -ETIMEDOUT; -out: + spin_lock(&xprt->transport_lock); + if (!req->rq_received) { + if (xprt->ops->timer) + xprt->ops->timer(task); + task->tk_status = -ETIMEDOUT; + } task->tk_timeout = 0; rpc_wake_up_task(task); spin_unlock(&xprt->transport_lock); diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 8589c1a..c3658ff 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -860,6 +860,17 @@ static void xs_tcp_set_buffer_size(struct rpc_xprt *xprt) return; } +/** + * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport + * @task: task that timed out + * + * Adjust the congestion window after a retransmit timeout has occurred. + */ +static void xs_udp_timer(struct rpc_task *task) +{ + xprt_adjust_cwnd(task, -ETIMEDOUT); +} + static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock) { struct sockaddr_in myaddr = { @@ -1050,6 +1061,7 @@ static struct rpc_xprt_ops xs_udp_ops = { .connect = xs_connect, .send_request = xs_udp_send_request, .set_retrans_timeout = xprt_set_retrans_timeout_rtt, + .timer = xs_udp_timer, .close = xs_close, .destroy = xs_destroy, }; -- 2.7.4