From ba11ad9a3b9dd2dbb9c6686ea9d41a9a77d94327 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg 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 Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- 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 1fcf2d1bcc3..c978557b4b8 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); -- 2.11.4.GIT