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[PATCH] RPC: separate TCP and UDP socket write paths
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 Split the RPC client's main socket write path into a TCP version and a UDP
 version to eliminate another dependency on the "xprt->stream" variable.

 Compiler optimization removes unneeded code from xs_sendpages, as this
 function is now called with some constant arguments.

 We can now cleanly perform transport protocol-specific return code testing
 and error recovery in each path.

 Test-plan:
 Millions of fsx operations.  Performance characterization such as
 "sio" or "iozone".  Examine oprofile results for any changes before and
 after this patch is applied.

 Version: Thu, 11 Aug 2005 16:08:46 -0400

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Chuck Lever authored and Trond Myklebust committed Sep 23, 2005
1 parent b0d93ad commit 262965f
Showing 1 changed file with 128 additions and 87 deletions.
215 changes: 128 additions & 87 deletions net/sunrpc/xprtsock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,12 @@
*/
#define XS_MAX_RESVPORT (800U)

/*
* How many times to try sending a request on a socket before waiting
* for the socket buffer to clear.
*/
#define XS_SENDMSG_RETRY (10U)

#ifdef RPC_DEBUG
# undef RPC_DEBUG_DATA
# define RPCDBG_FACILITY RPCDBG_TRANS
Expand Down Expand Up @@ -114,13 +120,18 @@ static int xs_send_tail(struct socket *sock, struct xdr_buf *xdr, unsigned int b
* @base: starting position in the buffer
*
*/
static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
static inline int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
{
struct page **ppage = xdr->pages;
unsigned int len, pglen = xdr->page_len;
int err, ret = 0;
ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);

if (unlikely(!sock))
return -ENOTCONN;

clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);

len = xdr->head[0].iov_len;
if (base < len || (addr != NULL && base == 0)) {
err = xs_send_head(sock, addr, addrlen, xdr, base, len);
Expand Down Expand Up @@ -187,140 +198,162 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
}

/**
* xs_sendmsg - write an RPC request to a socket
* @xprt: generic transport
* @req: the RPC request to write
* xs_nospace - place task on wait queue if transmit was incomplete
* @task: task to put to sleep
*
*/
static int xs_sendmsg(struct rpc_xprt *xprt, struct rpc_rqst *req)
static void xs_nospace(struct rpc_task *task)
{
struct socket *sock = xprt->sock;
struct xdr_buf *xdr = &req->rq_snd_buf;
struct sockaddr *addr = NULL;
int addrlen = 0;
unsigned int skip;
int result;
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;

if (!sock)
return -ENOTCONN;
dprintk("RPC: %4d xmit incomplete (%u left of %u)\n",
task->tk_pid, req->rq_slen - req->rq_bytes_sent,
req->rq_slen);

if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
/* Protect against races with write_space */
spin_lock_bh(&xprt->transport_lock);

/* Don't race with disconnect */
if (!xprt_connected(xprt))
task->tk_status = -ENOTCONN;
else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags))
xprt_wait_for_buffer_space(task);

spin_unlock_bh(&xprt->transport_lock);
} else
/* Keep holding the socket if it is blocked */
rpc_delay(task, HZ>>4);
}

/**
* xs_udp_send_request - write an RPC request to a UDP socket
* @task: address of RPC task that manages the state of an RPC request
*
* Return values:
* 0: The request has been sent
* EAGAIN: The socket was blocked, please call again later to
* complete the request
* ENOTCONN: Caller needs to invoke connect logic then call again
* other: Some other error occured, the request was not sent
*/
static int xs_udp_send_request(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
struct xdr_buf *xdr = &req->rq_snd_buf;
int status;

xs_pktdump("packet data:",
req->rq_svec->iov_base,
req->rq_svec->iov_len);

/* For UDP, we need to provide an address */
if (!xprt->stream) {
addr = (struct sockaddr *) &xprt->addr;
addrlen = sizeof(xprt->addr);
}
/* Don't repeat bytes */
skip = req->rq_bytes_sent;
req->rq_xtime = jiffies;
status = xs_sendpages(xprt->sock, (struct sockaddr *) &xprt->addr,
sizeof(xprt->addr), xdr, req->rq_bytes_sent);

clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
result = xs_sendpages(sock, addr, addrlen, xdr, skip);
dprintk("RPC: xs_udp_send_request(%u) = %d\n",
xdr->len - req->rq_bytes_sent, status);

dprintk("RPC: xs_sendmsg(%d) = %d\n", xdr->len - skip, result);
if (likely(status >= (int) req->rq_slen))
return 0;

if (result >= 0)
return result;
/* Still some bytes left; set up for a retry later. */
if (status > 0)
status = -EAGAIN;

switch (result) {
switch (status) {
case -ENETUNREACH:
case -EPIPE:
case -ECONNREFUSED:
/* When the server has died, an ICMP port unreachable message
* prompts ECONNREFUSED. */
case -EAGAIN:
break;
case -ECONNRESET:
case -ENOTCONN:
case -EPIPE:
/* connection broken */
if (xprt->stream)
result = -ENOTCONN;
case -EAGAIN:
xs_nospace(task);
break;
default:
dprintk("RPC: sendmsg returned unrecognized error %d\n",
-status);
break;
}
return result;

return status;
}

/**
* xs_send_request - write an RPC request to a socket
* xs_tcp_send_request - write an RPC request to a TCP socket
* @task: address of RPC task that manages the state of an RPC request
*
* Return values:
* 0: The request has been sent
* EAGAIN: The socket was blocked, please call again later to
* complete the request
* other: Some other error occured, the request was not sent
* 0: The request has been sent
* EAGAIN: The socket was blocked, please call again later to
* complete the request
* ENOTCONN: Caller needs to invoke connect logic then call again
* other: Some other error occured, the request was not sent
*
* XXX: In the case of soft timeouts, should we eventually give up
* if the socket is not able to make progress?
* if sendmsg is not able to make progress?
*/
static int xs_send_request(struct rpc_task *task)
static int xs_tcp_send_request(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
struct xdr_buf *xdr = &req->rq_snd_buf;
u32 *marker = req->rq_svec[0].iov_base;
int status, retry = 0;

/* set up everything as needed. */
/* Write the record marker */
if (xprt->stream) {
u32 *marker = req->rq_svec[0].iov_base;
*marker = htonl(0x80000000|(req->rq_slen-sizeof(*marker)));

*marker = htonl(0x80000000|(req->rq_slen-sizeof(*marker)));
}
xs_pktdump("packet data:",
req->rq_svec->iov_base,
req->rq_svec->iov_len);

/* Continue transmitting the packet/record. We must be careful
* to cope with writespace callbacks arriving _after_ we have
* called sendmsg().
*/
* called sendmsg(). */
while (1) {
req->rq_xtime = jiffies;
status = xs_sendmsg(xprt, req);
status = xs_sendpages(xprt->sock, NULL, 0, xdr,
req->rq_bytes_sent);

if (status < 0)
break;
dprintk("RPC: xs_tcp_send_request(%u) = %d\n",
xdr->len - req->rq_bytes_sent, status);

if (xprt->stream) {
req->rq_bytes_sent += status;

/* If we've sent the entire packet, immediately
* reset the count of bytes sent. */
if (req->rq_bytes_sent >= req->rq_slen) {
req->rq_bytes_sent = 0;
return 0;
}
} else {
if (status >= req->rq_slen)
return 0;
status = -EAGAIN;
if (unlikely(status < 0))
break;
}

dprintk("RPC: %4d xmit incomplete (%d left of %d)\n",
task->tk_pid, req->rq_slen - req->rq_bytes_sent,
req->rq_slen);
/* If we've sent the entire packet, immediately
* reset the count of bytes sent. */
req->rq_bytes_sent += status;
if (likely(req->rq_bytes_sent >= req->rq_slen)) {
req->rq_bytes_sent = 0;
return 0;
}

status = -EAGAIN;
if (retry++ > 50)
if (retry++ > XS_SENDMSG_RETRY)
break;
}

if (status == -EAGAIN) {
if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
/* Protect against races with write_space */
spin_lock_bh(&xprt->transport_lock);
/* Don't race with disconnect */
if (!xprt_connected(xprt))
task->tk_status = -ENOTCONN;
else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags))
xprt_wait_for_buffer_space(task);
spin_unlock_bh(&xprt->transport_lock);
return status;
}
/* Keep holding the socket if it is blocked */
rpc_delay(task, HZ>>4);
switch (status) {
case -EAGAIN:
xs_nospace(task);
break;
case -ECONNREFUSED:
case -ECONNRESET:
case -ENOTCONN:
case -EPIPE:
status = -ENOTCONN;
break;
default:
dprintk("RPC: sendmsg returned unrecognized error %d\n",
-status);
break;
}

return status;
}

Expand Down Expand Up @@ -992,10 +1025,18 @@ static void xs_connect(struct rpc_task *task)
}
}

static struct rpc_xprt_ops xs_ops = {
static struct rpc_xprt_ops xs_udp_ops = {
.set_buffer_size = xs_set_buffer_size,
.connect = xs_connect,
.send_request = xs_udp_send_request,
.close = xs_close,
.destroy = xs_destroy,
};

static struct rpc_xprt_ops xs_tcp_ops = {
.set_buffer_size = xs_set_buffer_size,
.connect = xs_connect,
.send_request = xs_send_request,
.send_request = xs_tcp_send_request,
.close = xs_close,
.destroy = xs_destroy,
};
Expand Down Expand Up @@ -1033,7 +1074,7 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)

INIT_WORK(&xprt->connect_worker, xs_udp_connect_worker, xprt);

xprt->ops = &xs_ops;
xprt->ops = &xs_udp_ops;

if (to)
xprt->timeout = *to;
Expand Down Expand Up @@ -1072,7 +1113,7 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)

INIT_WORK(&xprt->connect_worker, xs_tcp_connect_worker, xprt);

xprt->ops = &xs_ops;
xprt->ops = &xs_tcp_ops;

if (to)
xprt->timeout = *to;
Expand Down

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