Basic strategy of parallelizing sending/receiving iSCSI PDUs is like
this: offload do_recv(), do_send() and crc checking to worker threads
and do other part in the main event loop thread.
To follow the above strategy, this patch decomposes iscsi_rx_handler()
and iscsi_tx_handler() into some parts. Some of them can be called in
worker threads and others are not. In the future commit,
multi-threaded TCP event handler will be implemented based on
them. This patch re-implements single threaded TCP event handler
(past iscsi_tcp_event_handler(), renamed iscsi_tcp_st_event_handler())
based on these decomposed parts. iscsi_tcp_st_event_handler() is
also required because under some workload the multi-threaded version
degrades performance because of frequent communication between
threads.
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx>
---
usr/iscsi/iscsi_tcp.c | 47 +++++++++++++++++++++++-----
usr/iscsi/iscsid.c | 81 +++++++++++++++++++++++++++++--------------------
usr/iscsi/iscsid.h | 7 ++++-
3 files changed, 94 insertions(+), 41 deletions(-)
diff --git a/usr/iscsi/iscsi_tcp.c b/usr/iscsi/iscsi_tcp.c
index 4a9532a..9a41466 100644
--- a/usr/iscsi/iscsi_tcp.c
+++ b/usr/iscsi/iscsi_tcp.c
@@ -37,7 +37,7 @@
#include "util.h"
#include "work.h"
-static void iscsi_tcp_event_handler(int fd, int events, void *data);
+static void iscsi_tcp_st_event_handler(int fd, int events, void *data);
static void iscsi_tcp_release(struct iscsi_connection *conn);
static struct iscsi_task *iscsi_tcp_alloc_task(struct iscsi_connection *conn,
size_t ext_len);
@@ -255,7 +255,7 @@ static void accept_connection(int afd, int events, void *data)
conn_read_pdu(conn);
set_non_blocking(fd);
- ret = tgt_event_add(fd, EPOLLIN, iscsi_tcp_event_handler, conn);
+ ret = tgt_event_add(fd, EPOLLIN, iscsi_tcp_st_event_handler, conn);
if (ret) {
conn_exit(conn);
free(tcp_conn);
@@ -270,19 +270,52 @@ out:
return;
}
-static void iscsi_tcp_event_handler(int fd, int events, void *data)
+static void iscsi_tcp_st_event_handler(int fd, int events, void *data)
{
+ int ret;
+
struct iscsi_connection *conn = (struct iscsi_connection *) data;
- if (events & EPOLLIN)
- iscsi_rx_handler(conn);
+ if (events & EPOLLIN) {
+ if (is_conn_rx_bhs(conn)) {
+ ret = iscsi_rx_bhs_handler(conn);
+ if (!is_conn_rx_init_ahs(conn)
+ || ret < 0 || conn->state == STATE_CLOSE)
+ goto epollin_end;
+ }
+
+ if (conn->state != STATE_CLOSE && is_conn_rx_init_ahs(conn)) {
+ iscsi_pre_iostate_rx_init_ahs(conn);
+
+ if (conn->state == STATE_CLOSE)
+ goto epollin_end;
+ }
+
+ if (conn->state != STATE_CLOSE)
+ iscsi_rx_handler(conn);
+ if (conn->state != STATE_CLOSE && is_conn_rx_end(conn))
+ iscsi_rx_done(conn);
+ }
+
+epollin_end:
if (conn->state == STATE_CLOSE)
dprintf("connection closed\n");
- if (conn->state != STATE_CLOSE && events & EPOLLOUT)
- iscsi_tx_handler(conn);
+ if (conn->state != STATE_CLOSE && events & EPOLLOUT) {
+ if (conn->state == STATE_SCSI && !conn->tx_task) {
+ if (iscsi_task_tx_start(conn))
+ goto epollout_end;
+ }
+
+ if (conn->state != STATE_CLOSE)
+ iscsi_tx_handler(conn);
+
+ if (conn->state != STATE_CLOSE && is_conn_tx_end(conn))
+ iscsi_tx_done(conn);
+ }
+epollout_end:
if (conn->state == STATE_CLOSE) {
dprintf("connection closed %p\n", conn);
conn_close(conn);
diff --git a/usr/iscsi/iscsid.c b/usr/iscsi/iscsid.c
index c472608..c696d30 100644
--- a/usr/iscsi/iscsid.c
+++ b/usr/iscsi/iscsid.c
@@ -1991,7 +1991,7 @@ static int iscsi_task_tx_done(struct iscsi_connection *conn)
return 0;
}
-static int iscsi_task_tx_start(struct iscsi_connection *conn)
+int iscsi_task_tx_start(struct iscsi_connection *conn)
{
struct iscsi_task *task;
int is_rsp, err = 0;
@@ -2048,7 +2048,7 @@ static int do_recv(struct iscsi_connection *conn, int next_state)
return 0;
} else if (ret < 0) {
if (errno == EINTR || errno == EAGAIN)
- return 0;
+ return -errno;
else
return -EIO;
}
@@ -2066,7 +2066,30 @@ static int do_recv(struct iscsi_connection *conn, int next_state)
return ret;
}
-void iscsi_rx_handler(struct iscsi_connection *conn)
+int iscsi_rx_bhs_handler(struct iscsi_connection *conn)
+{
+ if (conn->rx_iostate != IOSTATE_RX_BHS) {
+ eprintf("invalid rx_iostate: %d\n", conn->rx_iostate);
+ exit(1);
+ }
+
+ return do_recv(conn, IOSTATE_RX_INIT_AHS);
+}
+
+void iscsi_pre_iostate_rx_init_ahs(struct iscsi_connection *conn)
+{
+ if (conn->state == STATE_SCSI) {
+ if (iscsi_task_rx_start(conn))
+ conn->state = STATE_CLOSE;
+ } else {
+ conn->rx_buffer = conn->req_buffer;
+ conn->req.ahs = conn->rx_buffer;
+ conn->req.data = conn->rx_buffer
+ + conn->req.bhs.hlength * 4;
+ }
+}
+
+int iscsi_rx_handler(struct iscsi_connection *conn)
{
int ret = 0, hdigest, ddigest;
uint32_t crc;
@@ -2080,23 +2103,7 @@ void iscsi_rx_handler(struct iscsi_connection *conn)
hdigest = ddigest = 0;
again:
switch (conn->rx_iostate) {
- case IOSTATE_RX_BHS:
- ret = do_recv(conn, IOSTATE_RX_INIT_AHS);
- if (ret <= 0 || conn->rx_iostate != IOSTATE_RX_INIT_AHS)
- break;
case IOSTATE_RX_INIT_AHS:
- if (conn->state == STATE_SCSI) {
- ret = iscsi_task_rx_start(conn);
- if (ret) {
- conn->state = STATE_CLOSE;
- break;
- }
- } else {
- conn->rx_buffer = conn->req_buffer;
- conn->req.ahs = conn->rx_buffer;
- conn->req.data = conn->rx_buffer
- + conn->req.bhs.hlength * 4;
- }
conn->req.ahssize = conn->req.bhs.hlength * 4;
conn->req.datasize = ntoh24(conn->req.bhs.dlength);
conn->rx_size = conn->req.ahssize;
@@ -2104,7 +2111,7 @@ again:
if (conn->state != STATE_SCSI &&
conn->req.ahssize > INCOMING_BUFSIZE) {
conn->state = STATE_CLOSE;
- return;
+ return -1;
}
if (conn->rx_size) {
@@ -2164,7 +2171,7 @@ again:
if (conn->req.ahssize + conn->rx_size >
INCOMING_BUFSIZE) {
conn->state = STATE_CLOSE;
- return;
+ return -1;
}
}
} else {
@@ -2202,10 +2209,11 @@ again:
exit(1);
}
- if (ret < 0 ||
- conn->rx_iostate != IOSTATE_RX_END ||
- conn->state == STATE_CLOSE)
- return;
+ if (ret < 0)
+ return ret;
+
+ if (conn->rx_iostate != IOSTATE_RX_END || conn->state == STATE_CLOSE)
+ return 0;
if (conn->rx_size) {
eprintf("error %d %d %d\n", conn->state, conn->rx_iostate,
@@ -2213,6 +2221,13 @@ again:
exit(1);
}
+ return 0;
+}
+
+void iscsi_rx_done(struct iscsi_connection *conn)
+{
+ int ret;
+
if (conn->state == STATE_SCSI) {
ret = iscsi_task_rx_done(conn);
if (ret)
@@ -2268,12 +2283,6 @@ int iscsi_tx_handler(struct iscsi_connection *conn)
} else
hdigest = ddigest = 0;
- if (conn->state == STATE_SCSI && !conn->tx_task) {
- ret = iscsi_task_tx_start(conn);
- if (ret)
- goto out;
- }
-
/*
* For rdma, grab the data-in or r2t packet and covert to
* an RDMA operation.
@@ -2393,6 +2402,14 @@ again:
finish:
cmnd_finish(conn);
+out:
+ return ret;
+}
+
+void iscsi_tx_done(struct iscsi_connection *conn)
+{
+ int ret;
+
switch (conn->state) {
case STATE_KERNEL:
ret = conn_take_fd(conn);
@@ -2416,8 +2433,6 @@ finish:
break;
}
-out:
- return ret;
}
int iscsi_transportid(int tid, uint64_t itn_id, char *buf, int size)
diff --git a/usr/iscsi/iscsid.h b/usr/iscsi/iscsid.h
index 01d0002..b795828 100644
--- a/usr/iscsi/iscsid.h
+++ b/usr/iscsi/iscsid.h
@@ -321,8 +321,13 @@ extern tgtadm_err conn_close_admin(uint32_t tid, uint64_t sid, uint32_t cid);
extern char *text_key_find(struct iscsi_connection *conn, char *searchKey);
extern void text_key_add(struct iscsi_connection *conn, char *key, char *value);
extern void conn_read_pdu(struct iscsi_connection *conn);
+extern int iscsi_task_tx_start(struct iscsi_connection *conn);
extern int iscsi_tx_handler(struct iscsi_connection *conn);
-extern void iscsi_rx_handler(struct iscsi_connection *conn);
+extern void iscsi_tx_done(struct iscsi_connection *conn);
+extern int iscsi_rx_bhs_handler(struct iscsi_connection *conn);
+extern void iscsi_pre_iostate_rx_init_ahs(struct iscsi_connection *conn);
+extern int iscsi_rx_handler(struct iscsi_connection *conn);
+extern void iscsi_rx_done(struct iscsi_connection *conn);
extern int iscsi_scsi_cmd_execute(struct iscsi_task *task);
extern int iscsi_transportid(int tid, uint64_t itn_id, char *buf, int size);
extern int iscsi_add_portal(char *addr, int port, int tpgt);
--
1.7.10.4
--
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