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SubjectRe: [PATCH] This extends tx_data and and iscsit_do_tx_data with the additional parameter flags and avoids sending multiple TCP packets in iscsit_fe_sendpage_sg
From
Date
On Sun, 2014-02-09 at 08:42 +0100, Eric Dumazet wrote:
> The new infrastructure is used in iscsit_fe_sendpage_sg to avoid sending three
> TCP packets instead of one by settings the MSG_MORE when calling kernel_sendmsg
> via the wrapper functions tx_data and iscsit_do_tx_data. This reduces the TCP
> overhead by sending the same data in less TCP packets and minimized the TCP RTP
> when TCP auto corking is enabled. When creating a 500 GB VMFS filesystem the
> filesystem is created in 3 seconds instead of 4 seconds.
>
> Signed-off-by: Thomas Glanzmann <thomas@glanzmann.de>
> X-tested-by: Thomas Glanzmann <thomas@glanzmann.de>
> ---

Hmm, thanks but this is not how to do this.

When you submit a patch written by someone else, you should :

1) Use your own identity as the sender, not impersonate me.
( thats standard convention )

2) Put following line as first line of the mail
( Documentation/SubmittingPatches lines ~565)

From: Eric Dumazet <edumazet@google.com>

Then I'll add my :
Signed-off-by: Eric Dumazet <edumazet@google.com>

Anyway, patch is not yet complete : We also want to set
MSG_MORE/MSG_SENDPAGE_NOTLAST for all pages but last one in a sg list.


This will fix suboptimal traffic :

13:32:04.976923 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [.], seq 289953:292849, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2896
13:32:04.976936 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [.], seq 292849:295745, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2896
13:32:04.976944 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [P.], seq 295745:298193, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2448
13:32:04.976952 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [.], seq 298193:301089, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2896
13:32:04.976960 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [.], seq 301089:303985, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2896
13:32:04.976998 IP 10.101.99.5.3260 > 10.101.0.12.43418: Flags [P.], seq 303985:306385, ack 45792, win 795, options [nop,nop,TS val 4294914045 ecr 1577012], length 2400

Please try following updated patch, thanks !

Once tested, we'll submit it formally.

drivers/target/iscsi/iscsi_target_parameters.c | 2
drivers/target/iscsi/iscsi_target_util.c | 38 +++++++++------
drivers/target/iscsi/iscsi_target_util.h | 2
3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_parameters.c b/drivers/target/iscsi/iscsi_target_parameters.c
index 4d2e23fc76fd..b80239250a1c 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.c
+++ b/drivers/target/iscsi/iscsi_target_parameters.c
@@ -79,7 +79,7 @@ int iscsi_login_tx_data(
*/
conn->if_marker += length;

- tx_sent = tx_data(conn, &iov[0], iov_cnt, length);
+ tx_sent = tx_data(conn, &iov[0], iov_cnt, length, 0);
if (tx_sent != length) {
pr_err("tx_data returned %d, expecting %d.\n",
tx_sent, length);
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 0819e688a398..3c529f7c61ce 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);
+ tx_sent = tx_data(conn, &iov, 1, tx_hdr_size,
+ cmd->tx_size != tx_hdr_size ? MSG_MORE : 0);
if (tx_hdr_size != tx_sent) {
if (tx_sent == -EAGAIN) {
pr_err("tx_data() returned -EAGAIN\n");
@@ -1225,18 +1226,24 @@ send_hdr:
while (data_len) {
u32 space = (sg->length - offset);
u32 sub_len = min_t(u32, data_len, space);
+ int flags = 0;
+
+ if ((data_len != sub_len) || cmd->padding ||
+ conn->conn_ops->DataDigest)
+ flags = MSG_SENDPAGE_NOTLAST | MSG_MORE;
+
send_pg:
tx_sent = conn->sock->ops->sendpage(conn->sock,
- sg_page(sg), sg->offset + offset, sub_len, 0);
+ sg_page(sg),
+ sg->offset + offset,
+ sub_len, flags);
if (tx_sent != sub_len) {
if (tx_sent == -EAGAIN) {
- pr_err("tcp_sendpage() returned"
- " -EAGAIN\n");
+ pr_err("tcp_sendpage() returned -EAGAIN\n");
goto send_pg;
}

- pr_err("tcp_sendpage() failure: %d\n",
- tx_sent);
+ pr_err("tcp_sendpage() failure: %d\n", tx_sent);
return -1;
}

@@ -1249,7 +1256,8 @@ 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 +1271,7 @@ 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 +1357,12 @@ 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 +1372,6 @@ 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 +1415,8 @@ 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 +1429,7 @@ 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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