From ba11ad9a3b9dd2dbb9c6686ea9d41a9a77d94327 Mon Sep 17 00:00:00 2001
From: Lars Ellenberg <lars.ellenberg@linbit.com>
Date: Tue, 25 May 2010 16:26:16 +0200
Subject: [PATCH] drbd: improve usage of MSG_MORE
It seems to improve performance if we allow the "p_data" header in its
own frame (no MSG_MORE), but sendpage all but the last page with MSG_MORE.
This is also in preparation of a later zero copy receive implementation.
Suggested by Eduard.Guzovsky@stratus.com on drbd-dev.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
drivers/block/drbd/drbd_main.c | 32 +++++++++++++++++++-------------
1 file changed, 19 insertions(+), 13 deletions(-)
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 1fcf2d1bcc39..c978557b4b80 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2272,9 +2272,9 @@ static int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket *
* with page_count == 0 or PageSlab.
*/
static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
- int offset, size_t size)
+ int offset, size_t size, unsigned msg_flags)
{
- int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, 0);
+ int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, msg_flags);
kunmap(page);
if (sent == size)
mdev->send_cnt += size>>9;
@@ -2282,7 +2282,7 @@ static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
}
static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
- int offset, size_t size)
+ int offset, size_t size, unsigned msg_flags)
{
mm_segment_t oldfs = get_fs();
int sent, ok;
@@ -2295,14 +2295,15 @@ static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
* __page_cache_release a page that would actually still be referenced
* by someone, leading to some obscure delayed Oops somewhere else. */
if (disable_sendpage || (page_count(page) < 1) || PageSlab(page))
- return _drbd_no_send_page(mdev, page, offset, size);
+ return _drbd_no_send_page(mdev, page, offset, size, msg_flags);
+ msg_flags |= MSG_NOSIGNAL;
drbd_update_congested(mdev);
set_fs(KERNEL_DS);
do {
sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,
offset, len,
- MSG_NOSIGNAL);
+ msg_flags);
if (sent == -EAGAIN) {
if (we_should_drop_the_connection(mdev,
mdev->data.socket))
@@ -2331,9 +2332,11 @@ static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
{
struct bio_vec *bvec;
int i;
+ /* hint all but last page with MSG_MORE */
__bio_for_each_segment(bvec, bio, i, 0) {
if (!_drbd_no_send_page(mdev, bvec->bv_page,
- bvec->bv_offset, bvec->bv_len))
+ bvec->bv_offset, bvec->bv_len,
+ i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
return 0;
}
return 1;
@@ -2343,12 +2346,13 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
{
struct bio_vec *bvec;
int i;
+ /* hint all but last page with MSG_MORE */
__bio_for_each_segment(bvec, bio, i, 0) {
if (!_drbd_send_page(mdev, bvec->bv_page,
- bvec->bv_offset, bvec->bv_len))
+ bvec->bv_offset, bvec->bv_len,
+ i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
return 0;
}
-
return 1;
}
@@ -2356,9 +2360,11 @@ static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
{
struct page *page = e->pages;
unsigned len = e->size;
+ /* hint all but last page with MSG_MORE */
page_chain_for_each(page) {
unsigned l = min_t(unsigned, len, PAGE_SIZE);
- if (!_drbd_send_page(mdev, page, 0, l))
+ if (!_drbd_send_page(mdev, page, 0, l,
+ page_chain_next(page) ? MSG_MORE : 0))
return 0;
len -= l;
}
@@ -2438,11 +2444,11 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
p.dp_flags = cpu_to_be32(dp_flags);
set_bit(UNPLUG_REMOTE, &mdev->flags);
ok = (sizeof(p) ==
- drbd_send(mdev, mdev->data.socket, &p, sizeof(p), MSG_MORE));
+ drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0));
if (ok && dgs) {
dgb = mdev->int_dig_out;
drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
- ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
+ ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
}
if (ok) {
if (mdev->net_conf->wire_protocol == DRBD_PROT_A)
@@ -2491,11 +2497,11 @@ int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
return 0;
ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p,
- sizeof(p), MSG_MORE);
+ sizeof(p), dgs ? MSG_MORE : 0);
if (ok && dgs) {
dgb = mdev->int_dig_out;
drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);
- ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
+ ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
}
if (ok)
ok = _drbd_send_zc_ee(mdev, e);