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iscsi: Fix performance degradation due to sock_readv

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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: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/448021
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Ziye Yang <ziye.yang@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
This commit is contained in:
Shuhei Matsumoto 2019-03-14 18:02:33 +09:00 committed by Jim Harris
parent 1bec7d572c
commit 8353d56e77
1 changed files with 41 additions and 12 deletions
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53
lib/iscsi/conn.c
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@ -875,6 +875,42 @@ 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_read_data(struct spdk_iscsi_conn *conn, int bytes,
void *buf)
{
int ret;
if (bytes == 0) {
return 0;
}
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);
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_recv() failed, errno %d: %s\n",
errno, spdk_strerror(errno));
} else {
SPDK_ERRLOG("spdk_sock_recv() failed, errno %d: %s\n",
errno, spdk_strerror(errno));
}
}
/* connection closed */
return SPDK_ISCSI_CONNECTION_FATAL;
}
int
spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn,
struct iovec *iov, int iovcnt)
@ -885,6 +921,11 @@ spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn,
return 0;
}
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) {
@ -911,18 +952,6 @@ spdk_iscsi_conn_readv_data(struct spdk_iscsi_conn *conn,
return SPDK_ISCSI_CONNECTION_FATAL;
}
int
spdk_iscsi_conn_read_data(struct spdk_iscsi_conn *conn, int bytes,
void *buf)
{
struct iovec iov;
iov.iov_base = buf;
iov.iov_len = bytes;
return spdk_iscsi_conn_readv_data(conn, &iov, 1);
}
void
spdk_iscsi_task_mgmt_cpl(struct spdk_scsi_task *scsi_task)
{