linux-kernel - [RFC PATCH] nvme: request remote is usually not involved for nvme devices

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Message-Id: <1663432858-99743-1-git-send-email-liusong@linux.alibaba.com>
Date:   Sun, 18 Sep 2022 00:40:58 +0800
From:   Liu Song <liusong@...ux.alibaba.com>
To:     kbusch@...nel.org, axboe@...com, hch@....de, sagi@...mberg.me
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH] nvme: request remote is usually not involved for nvme devices

From: Liu Song <liusong@...ux.alibaba.com>

NVMe devices usually have a 1:1 mapping between "ctx" and "hctx",
so when "nr_ctx" is equal to 1, there is no possibility of remote
request, so the corresponding process can be simplified.

Signed-off-by: Liu Song <liusong@...ux.alibaba.com>
---
 drivers/nvme/host/nvme.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 216acbe..cc21896 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -672,6 +672,10 @@ static inline bool nvme_try_complete_req(struct request *req, __le16 status,
 	nvme_should_fail(req);
 	if (unlikely(blk_should_fake_timeout(req->q)))
 		return true;
+	if (likely(req->mq_hctx->nr_ctx == 1)) {
+		WRITE_ONCE(req->state, MQ_RQ_COMPLETE);
+		return false;
+	}
 	return blk_mq_complete_request_remote(req);
 }
 
-- 
1.8.3.1