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[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 <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Chuck Lever 2005-08-25 16:25:52 -07:00 committed by Trond Myklebust
parent 49e9a89086
commit 46c0ee8bc4
3 changed files with 34 additions and 25 deletions
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2
include/linux/sunrpc/xprt.h
View File

@ -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);

45
net/sunrpc/xprt.c
View File

@ -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;
dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
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 (%s request)\n",
task->tk_pid, req ? "pending" : "backlogged");
task->tk_status = -ETIMEDOUT;
out:
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);

12
net/sunrpc/xprtsock.c
View File

@ -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,
};