From c965a0299c6123d259ef0d4841f9fa3e1dee3e58 Mon Sep 17 00:00:00 2001 From: Sagi Grimberg Date: Thu, 12 Mar 2020 16:06:38 -0700 Subject: [PATCH] nvmet-tcp: set MSG_MORE only if we actually have more to send commit 98fd5c723730f560e5bea919a64ac5b83d45eb72 upstream. When we send PDU data, we want to optimize the tcp stack operation if we have more data to send. So when we set MSG_MORE when: - We have more fragments coming in the batch, or - We have a more data to send in this PDU - We don't have a data digest trailer - We optimize with the SUCCESS flag and omit the NVMe completion (used if sq_head pointer update is disabled) This addresses a regression in QD=1 with SUCCESS flag optimization as we unconditionally set MSG_MORE when we didn't actually have more data to send. Fixes: 70583295388a ("nvmet-tcp: implement C2HData SUCCESS optimization") Reported-by: Mark Wunderlich Tested-by: Mark Wunderlich Signed-off-by: Sagi Grimberg Signed-off-by: Keith Busch Signed-off-by: Greg Kroah-Hartman --- drivers/nvme/target/tcp.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c index d535080..2fe34fd 100644 --- a/drivers/nvme/target/tcp.c +++ b/drivers/nvme/target/tcp.c @@ -515,7 +515,7 @@ static int nvmet_try_send_data_pdu(struct nvmet_tcp_cmd *cmd) return 1; } -static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd) +static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd, bool last_in_batch) { struct nvmet_tcp_queue *queue = cmd->queue; int ret; @@ -523,9 +523,15 @@ static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd) while (cmd->cur_sg) { struct page *page = sg_page(cmd->cur_sg); u32 left = cmd->cur_sg->length - cmd->offset; + int flags = MSG_DONTWAIT; + + if ((!last_in_batch && cmd->queue->send_list_len) || + cmd->wbytes_done + left < cmd->req.transfer_len || + queue->data_digest || !queue->nvme_sq.sqhd_disabled) + flags |= MSG_MORE; ret = kernel_sendpage(cmd->queue->sock, page, cmd->offset, - left, MSG_DONTWAIT | MSG_MORE); + left, flags); if (ret <= 0) return ret; @@ -660,7 +666,7 @@ static int nvmet_tcp_try_send_one(struct nvmet_tcp_queue *queue, } if (cmd->state == NVMET_TCP_SEND_DATA) { - ret = nvmet_try_send_data(cmd); + ret = nvmet_try_send_data(cmd, last_in_batch); if (ret <= 0) goto done_send; } -- 2.7.4