From: Sagi Grimberg <sagi@grimberg.me>
Date: Thu, 18 Jun 2020 17:30:23 -0700
Subject: [PATCH] nvme-tcp: leverage request plugging
Git-commit: 86f0348ace1510d7ac25124b096fb88a6ab45270
Patch-mainline: v5.9-rc1
References: bsc#1179519
blk-mq request plugging can improve the execution of our pipeline.
When we queue a request we actually trigger our I/O worker thread
yielding a context switch by definition. However if we know that
there are more requests in the pipe that are coming, we are better
off not trigger our I/O worker and only do that for the last request
in the batch (bd->last). By having it, we improve efficiency by
amortizing context switches over a batch of requests.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/nvme/host/tcp.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 478868572c81..2d3962c164a4 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -262,7 +262,7 @@ static inline void nvme_tcp_advance_req(struct nvme_tcp_request *req,
}
static inline void nvme_tcp_queue_request(struct nvme_tcp_request *req,
- bool sync)
+ bool sync, bool last)
{
struct nvme_tcp_queue *queue = req->queue;
bool empty;
@@ -279,7 +279,7 @@ static inline void nvme_tcp_queue_request(struct nvme_tcp_request *req,
sync && empty && mutex_trylock(&queue->send_mutex)) {
nvme_tcp_try_send(queue);
mutex_unlock(&queue->send_mutex);
- } else {
+ } else if (last) {
queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
}
}
@@ -610,7 +610,7 @@ static int nvme_tcp_handle_r2t(struct nvme_tcp_queue *queue,
req->state = NVME_TCP_SEND_H2C_PDU;
req->offset = 0;
- nvme_tcp_queue_request(req, false);
+ nvme_tcp_queue_request(req, false, true);
return 0;
}
@@ -2120,7 +2120,7 @@ static void nvme_tcp_submit_async_event(struct nvme_ctrl *arg)
ctrl->async_req.curr_bio = NULL;
ctrl->async_req.data_len = 0;
- nvme_tcp_queue_request(&ctrl->async_req, true);
+ nvme_tcp_queue_request(&ctrl->async_req, true, true);
}
static enum blk_eh_timer_return
@@ -2232,6 +2232,14 @@ static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
return 0;
}
+static void nvme_tcp_commit_rqs(struct blk_mq_hw_ctx *hctx)
+{
+ struct nvme_tcp_queue *queue = hctx->driver_data;
+
+ if (!llist_empty(&queue->req_list))
+ queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
+}
+
static blk_status_t nvme_tcp_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
@@ -2251,7 +2259,7 @@ static blk_status_t nvme_tcp_queue_rq(struct blk_mq_hw_ctx *hctx,
blk_mq_start_request(rq);
- nvme_tcp_queue_request(req, true);
+ nvme_tcp_queue_request(req, true, bd->last);
return BLK_STS_OK;
}
@@ -2319,6 +2327,7 @@ static int nvme_tcp_poll(struct blk_mq_hw_ctx *hctx)
static struct blk_mq_ops nvme_tcp_mq_ops = {
.queue_rq = nvme_tcp_queue_rq,
+ .commit_rqs = nvme_tcp_commit_rqs,
.complete = nvme_complete_rq,
.init_request = nvme_tcp_init_request,
.exit_request = nvme_tcp_exit_request,
--
2.16.4