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authorSagi Grimberg <sagi@grimberg.me>2020-03-12 16:06:38 -0700
committerKeith Busch <kbusch@kernel.org>2020-03-21 04:37:53 +0900
commit98fd5c723730f560e5bea919a64ac5b83d45eb72 (patch)
tree1f9302e25a129c5f9655151dd6b5701d911d81ee
parent9134ae2a2546cb96abddcd4469a79c77ee3a4480 (diff)
nvmet-tcp: set MSG_MORE only if we actually have more to send
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 <mark.wunderlich@intel.com> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Keith Busch <kbusch@kernel.org>
-rw-r--r--drivers/nvme/target/tcp.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index af674fc0bb1e..5bb5342b8d0c 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;
}