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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]
Hello Eric,

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

thank you for your patch. It did not apply on top of Linux tip, so I put
in the changes manually and fixed up another call to tx_data that your
forgot in your initial patch to make it apply.

I gave it another run, can you confirm that it now behaves better?

https://thomas.glanzmann.de/tmp/tcp_auto_corking_on_patched_tcp_more.pcap.bz2

And look at that roundtrip graph it is perfect. Also filesystem is now
created in 3 seconds instead of 4.

https://thomas.glanzmann.de/tmp/screenshot-mini-2014-02-08-22:34:57.png

Nab, do you consider this patch for upstream? Would you take if I clean
it up?

Cheers,
Thomas

PS: I'm asleep for the next 8 hours.

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index e655b04..0eb9681 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1168,7 +1168,7 @@ 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");
@@ -1199,7 +1199,8 @@ 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");
@@ -1208,7 +1209,6 @@ 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[]
@@ -1252,7 +1252,8 @@ 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");
@@ -1266,7 +1267,7 @@ 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");
@@ -1352,11 +1353,13 @@ 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;
@@ -1366,8 +1369,6 @@ static int iscsit_do_tx_data(
return -1;
}

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

@@ -1411,7 +1412,8 @@ int tx_data(
struct iscsi_conn *conn,
struct kvec *iov,
int iov_count,
- int data)
+ int data,
+ int flags)
{
struct iscsi_data_count c;

@@ -1424,7 +1426,7 @@ 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);
}

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