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Commit b4b5cc85 authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust
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[PATCH] RPC: Reduce stack utilization in xs_sendpages 



 Reduce stack utilization of the RPC socket transport's send path.

 A couple of unlikely()s are added to ensure the compiler places the
 tail processing at the end of the csect.

 Test-plan:
 Millions of fsx operations.  Performance characterization such as "sio" or
 "iozone".

 Version: Thu, 11 Aug 2005 16:04:30 -0400

 Signed-off-by: default avatarChuck Lever <cel@netapp.com>
 Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 9903cd1c

net/sunrpc/xprtsock.c

+43 −30
Original line number Diff line number Diff line
@@ -68,6 +68,41 @@ static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count) 
}

#endif



#define XS_SENDMSG_FLAGS	(MSG_DONTWAIT | MSG_NOSIGNAL)



static inline int xs_send_head(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base, unsigned int len)

{

	struct kvec iov = {

		.iov_base	= xdr->head[0].iov_base + base,

		.iov_len	= len - base,

	};

	struct msghdr msg = {

		.msg_name	= addr,

		.msg_namelen	= addrlen,

		.msg_flags	= XS_SENDMSG_FLAGS,

	};



	if (xdr->len > len)

		msg.msg_flags |= MSG_MORE;



	if (likely(iov.iov_len))

		return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);

	return kernel_sendmsg(sock, &msg, NULL, 0, 0);

}



static int xs_send_tail(struct socket *sock, struct xdr_buf *xdr, unsigned int base, unsigned int len)

{

	struct kvec iov = {

		.iov_base	= xdr->tail[0].iov_base + base,

		.iov_len	= len - base,

	};

	struct msghdr msg = {

		.msg_flags	= XS_SENDMSG_FLAGS,

	};



	return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);

}



/**

 * xs_sendpages - write pages directly to a socket

 * @sock: socket to send on
@@ -77,7 +112,7 @@ static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count) 
 * @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, int msgflags)

static 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;
@@ -86,35 +121,20 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, 


	len = xdr->head[0].iov_len;

	if (base < len || (addr != NULL && base == 0)) {

		struct kvec iov = {

			.iov_base = xdr->head[0].iov_base + base,

			.iov_len  = len - base,

		};

		struct msghdr msg = {

			.msg_name    = addr,

			.msg_namelen = addrlen,

			.msg_flags   = msgflags,

		};

		if (xdr->len > len)

			msg.msg_flags |= MSG_MORE;



		if (iov.iov_len != 0)

			err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);

		else

			err = kernel_sendmsg(sock, &msg, NULL, 0, 0);

		err = xs_send_head(sock, addr, addrlen, xdr, base, len);

		if (ret == 0)

			ret = err;

		else if (err > 0)

			ret += err;

		if (err != iov.iov_len)

		if (err != (len - base))

			goto out;

		base = 0;

	} else

		base -= len;



	if (pglen == 0)

	if (unlikely(pglen == 0))

		goto copy_tail;

	if (base >= pglen) {

	if (unlikely(base >= pglen)) {

		base -= pglen;

		goto copy_tail;

	}
@@ -127,7 +147,7 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, 


	sendpage = sock->ops->sendpage ? : sock_no_sendpage;

	do {

		int flags = msgflags;

		int flags = XS_SENDMSG_FLAGS;



		len = PAGE_CACHE_SIZE;

		if (base)
@@ -154,14 +174,7 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, 
copy_tail:

	len = xdr->tail[0].iov_len;

	if (base < len) {

		struct kvec iov = {

			.iov_base = xdr->tail[0].iov_base + base,

			.iov_len  = len - base,

		};

		struct msghdr msg = {

			.msg_flags   = msgflags,

		};

		err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);

		err = xs_send_tail(sock, xdr, base, len);

		if (ret == 0)

			ret = err;

		else if (err > 0)
@@ -202,7 +215,7 @@ static int xs_sendmsg(struct rpc_xprt *xprt, struct rpc_rqst *req) 
	skip = req->rq_bytes_sent;



	clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);

	result = xs_sendpages(sock, addr, addrlen, xdr, skip, MSG_DONTWAIT);

	result = xs_sendpages(sock, addr, addrlen, xdr, skip);



	dprintk("RPC:      xs_sendmsg(%d) = %d\n", xdr->len - skip, result);