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SubjectRe: REGRESSION f54b311142a92ea2e42598e347b84e1655caf8e3 tcp auto corking slows down iSCSI file system creation by factor of 70 [WAS: 4 TB VMFS creation takes 15 minutes vs 26 seconds]
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On Sat, 2014-02-08 at 18:15 +0100, Thomas Glanzmann wrote:

> The iSCSI target uses one function to send all outbound data. So in
> order to do it right every function that is sending data in multiple
> chunks need to mark it correctly. Of course someone could also do some
> wild guessing and saying that everything that is below 512 Bytes gets
> pushed out. I wonder what Nab has to say about this?

I was simply thinking about something like :
(might need further changes, but I guess this should solve your case)

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 0819e688a398..44f0d62a88d6 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1165,7 +1165,7 @@ send_data:
iov_count = cmd->iov_misc_count;
}

- tx_sent = tx_data(conn, &iov[0], iov_count, tx_size);
+ tx_sent = tx_data(conn, &iov[0], iov_count, tx_size, 0);
if (tx_size != tx_sent) {
if (tx_sent == -EAGAIN) {
pr_err("tx_data() returned -EAGAIN\n");
@@ -1196,7 +1196,8 @@ send_hdr:
iov.iov_base = cmd->pdu;
iov.iov_len = tx_hdr_size;

- tx_sent = tx_data(conn, &iov, 1, tx_hdr_size);
+ data_len = cmd->tx_size - tx_hdr_size - cmd->padding;
+ tx_sent = tx_data(conn, &iov, 1, tx_hdr_size, data_len ? MSG_MORE : 0);
if (tx_hdr_size != tx_sent) {
if (tx_sent == -EAGAIN) {
pr_err("tx_data() returned -EAGAIN\n");
@@ -1205,7 +1206,6 @@ send_hdr:
return -1;
}

- data_len = cmd->tx_size - tx_hdr_size - cmd->padding;
/*
* Set iov_off used by padding and data digest tx_data() calls below
* in order to determine proper offset into cmd->iov_data[]
@@ -1249,7 +1249,8 @@ send_padding:
if (cmd->padding) {
struct kvec *iov_p = &cmd->iov_data[iov_off++];

- tx_sent = tx_data(conn, iov_p, 1, cmd->padding);
+ tx_sent = tx_data(conn, iov_p, 1, cmd->padding,
+ conn->conn_ops->DataDigest ? MSG_MORE : 0);
if (cmd->padding != tx_sent) {
if (tx_sent == -EAGAIN) {
pr_err("tx_data() returned -EAGAIN\n");
@@ -1263,7 +1264,7 @@ send_datacrc:
if (conn->conn_ops->DataDigest) {
struct kvec *iov_d = &cmd->iov_data[iov_off];

- tx_sent = tx_data(conn, iov_d, 1, ISCSI_CRC_LEN);
+ tx_sent = tx_data(conn, iov_d, 1, ISCSI_CRC_LEN, 0);
if (ISCSI_CRC_LEN != tx_sent) {
if (tx_sent == -EAGAIN) {
pr_err("tx_data() returned -EAGAIN\n");
@@ -1349,11 +1350,12 @@ static int iscsit_do_rx_data(

static int iscsit_do_tx_data(
struct iscsi_conn *conn,
- struct iscsi_data_count *count)
+ struct iscsi_data_count *count,
+ int flags)
{
int data = count->data_length, total_tx = 0, tx_loop = 0, iov_len;
struct kvec *iov_p;
- struct msghdr msg;
+ struct msghdr msg = { .msg_flags = flags };

if (!conn || !conn->sock || !conn->conn_ops)
return -1;
@@ -1363,8 +1365,6 @@ static int iscsit_do_tx_data(
return -1;
}

- memset(&msg, 0, sizeof(struct msghdr));
-
iov_p = count->iov;
iov_len = count->iov_count;

@@ -1408,7 +1408,8 @@ int tx_data(
struct iscsi_conn *conn,
struct kvec *iov,
int iov_count,
- int data)
+ int data,
+ int flags)
{
struct iscsi_data_count c;

@@ -1421,7 +1422,7 @@ int tx_data(
c.data_length = data;
c.type = ISCSI_TX_DATA;

- return iscsit_do_tx_data(conn, &c);
+ return iscsit_do_tx_data(conn, &c, flags);
}

void iscsit_collect_login_stats(
diff --git a/drivers/target/iscsi/iscsi_target_util.h b/drivers/target/iscsi/iscsi_target_util.h
index e4fc34a02f57..1b4f06801adc 100644
--- a/drivers/target/iscsi/iscsi_target_util.h
+++ b/drivers/target/iscsi/iscsi_target_util.h
@@ -54,7 +54,7 @@ extern int iscsit_print_dev_to_proc(char *, char **, off_t, int);
extern int iscsit_print_sessions_to_proc(char *, char **, off_t, int);
extern int iscsit_print_tpg_to_proc(char *, char **, off_t, int);
extern int rx_data(struct iscsi_conn *, struct kvec *, int, int);
-extern int tx_data(struct iscsi_conn *, struct kvec *, int, int);
+extern int tx_data(struct iscsi_conn *, struct kvec *, int, int, int);
extern void iscsit_collect_login_stats(struct iscsi_conn *, u8, u8);
extern struct iscsi_tiqn *iscsit_snmp_get_tiqn(struct iscsi_conn *);




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