From: Keith Busch <kbusch@kernel.org>
To: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me
Cc: Keith Busch <kbusch@kernel.org>
Subject: [PATCH] nvme-pci: remove last_sq_tail
Date: Mon, 27 Apr 2020 11:54:46 -0700 [thread overview]
Message-ID: <20200427185446.2139232-1-kbusch@kernel.org> (raw)
The nvme driver does not have enough tags to wrap the queue, and blk-mq
will no longer call commit_rqs() when there are no new submissions to
notify.
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
drivers/nvme/host/pci.c | 23 ++++-------------------
1 file changed, 4 insertions(+), 19 deletions(-)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4e79e412b276..8ebcf40f04fe 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -173,7 +173,6 @@ struct nvme_queue {
u16 q_depth;
u16 cq_vector;
u16 sq_tail;
- u16 last_sq_tail;
u16 cq_head;
u16 qid;
u8 cq_phase;
@@ -446,24 +445,11 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
return 0;
}
-/*
- * Write sq tail if we are asked to, or if the next command would wrap.
- */
-static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq)
+static inline void nvme_write_sq_db(struct nvme_queue *nvmeq)
{
- if (!write_sq) {
- u16 next_tail = nvmeq->sq_tail + 1;
-
- if (next_tail == nvmeq->q_depth)
- next_tail = 0;
- if (next_tail != nvmeq->last_sq_tail)
- return;
- }
-
if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail,
nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei))
writel(nvmeq->sq_tail, nvmeq->q_db);
- nvmeq->last_sq_tail = nvmeq->sq_tail;
}
/**
@@ -480,7 +466,8 @@ static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd,
cmd, sizeof(*cmd));
if (++nvmeq->sq_tail == nvmeq->q_depth)
nvmeq->sq_tail = 0;
- nvme_write_sq_db(nvmeq, write_sq);
+ if (write_sq)
+ nvme_write_sq_db(nvmeq);
spin_unlock(&nvmeq->sq_lock);
}
@@ -489,8 +476,7 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx)
struct nvme_queue *nvmeq = hctx->driver_data;
spin_lock(&nvmeq->sq_lock);
- if (nvmeq->sq_tail != nvmeq->last_sq_tail)
- nvme_write_sq_db(nvmeq, true);
+ nvme_write_sq_db(nvmeq);
spin_unlock(&nvmeq->sq_lock);
}
@@ -1489,7 +1475,6 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
struct nvme_dev *dev = nvmeq->dev;
nvmeq->sq_tail = 0;
- nvmeq->last_sq_tail = 0;
nvmeq->cq_head = 0;
nvmeq->cq_phase = 1;
nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
--
2.24.1
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next reply other threads:[~2020-04-27 18:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 18:54 Keith Busch [this message]
2020-04-29 0:07 ` [PATCH] nvme-pci: remove last_sq_tail Sagi Grimberg
2020-05-01 13:01 ` Christoph Hellwig
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