Commit 8353d56e authored by Shuhei Matsumoto's avatar Shuhei Matsumoto Committed by Jim Harris
Browse files

iscsi: Fix performance degradation due to sock_readv 



spdk_iscsi_conn_read_data was changed to use sock_readv
instead of sock_recv as a refactoring effort.
However this change caused about 3% performance degradation
for write I/O.

Hence this patch changes spdk_iscsi_conn_read_data to use
sock_recv and changes spdk_iscsi_conn_readv_data to call
spdk_iscsi_conn_read_data if iovcnt is 1.

Change-Id: I5fcad03ff23dee4e9954eee879225d3c493be52e
Signed-off-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/448021


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
Reviewed-by: default avatarZiye Yang <ziye.yang@intel.com>
Reviewed-by: default avatarTomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
parent 1bec7d57

lib/iscsi/conn.c

+41 −12
Original line number Diff line number Diff line
@@ -876,16 +876,16 @@ spdk_iscsi_drop_conns(struct spdk_iscsi_conn *conn, const char *conn_match, 
 * Otherwise returns the number of bytes successfully read.

 */

int

spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn,

			   struct iovec *iov, int iovcnt)

spdk_iscsi_conn_read_data(struct spdk_iscsi_conn *conn, int bytes,

			  void *buf)

{

	int ret;



	if (iov == NULL || iovcnt == 0) {

	if (bytes == 0) {

		return 0;

	}



	ret = spdk_sock_readv(conn->sock, iov, iovcnt);

	ret = spdk_sock_recv(conn->sock, buf, bytes);



	if (ret > 0) {

		spdk_trace_record(TRACE_ISCSI_READ_FROM_SOCKET_DONE, conn->id, ret, 0, 0);
@@ -899,10 +899,10 @@ spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn, 


		/* For connect reset issue, do not output error log */

		if (errno == ECONNRESET) {

			SPDK_DEBUGLOG(SPDK_LOG_ISCSI, "spdk_sock_readv() failed, errno %d: %s\n",

			SPDK_DEBUGLOG(SPDK_LOG_ISCSI, "spdk_sock_recv() failed, errno %d: %s\n",

				      errno, spdk_strerror(errno));

		} else {

			SPDK_ERRLOG("spdk_sock_readv() failed, errno %d: %s\n",

			SPDK_ERRLOG("spdk_sock_recv() failed, errno %d: %s\n",

				    errno, spdk_strerror(errno));

		}

	}
@@ -912,15 +912,44 @@ spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn, 
}



int

spdk_iscsi_conn_read_data(struct spdk_iscsi_conn *conn, int bytes,

			  void *buf)

spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn,

			   struct iovec *iov, int iovcnt)

{

	struct iovec iov;

	int ret;



	iov.iov_base = buf;

	iov.iov_len = bytes;

	if (iov == NULL || iovcnt == 0) {

		return 0;

	}



	return spdk_iscsi_conn_readv_data(conn, &iov, 1);

	if (iovcnt == 1) {

		return spdk_iscsi_conn_read_data(conn, iov[0].iov_len,

						 iov[0].iov_base);

	}



	ret = spdk_sock_readv(conn->sock, iov, iovcnt);



	if (ret > 0) {

		spdk_trace_record(TRACE_ISCSI_READ_FROM_SOCKET_DONE, conn->id, ret, 0, 0);

		return ret;

	}



	if (ret < 0) {

		if (errno == EAGAIN || errno == EWOULDBLOCK) {

			return 0;

		}



		/* For connect reset issue, do not output error log */

		if (errno == ECONNRESET) {

			SPDK_DEBUGLOG(SPDK_LOG_ISCSI, "spdk_sock_readv() failed, errno %d: %s\n",

				      errno, spdk_strerror(errno));

		} else {

			SPDK_ERRLOG("spdk_sock_readv() failed, errno %d: %s\n",

				    errno, spdk_strerror(errno));

		}

	}



	/* connection closed */

	return SPDK_ISCSI_CONNECTION_FATAL;

}



void