From: Jeffle Xu <jefflexu@linux.alibaba.com>
To: snitzer@redhat.com, axboe@kernel.dk
Cc: hch@lst.de, ming.lei@redhat.com, linux-block@vger.kernel.org,
dm-devel@redhat.com, io-uring@vger.kernel.org,
joseph.qi@linux.alibaba.com, caspar@linux.alibaba.com
Subject: [PATCH v4 09/12] nvme/pci: don't wait for locked polling queue
Date: Sat, 20 Feb 2021 19:06:34 +0800 [thread overview]
Message-ID: <20210220110637.50305-10-jefflexu@linux.alibaba.com> (raw)
In-Reply-To: <20210220110637.50305-1-jefflexu@linux.alibaba.com>
There's no sense waiting for the hw queue when it currently has been
locked by another polling instance. The polling instance currently
occupying the hw queue will help reap the completion events.
It shall be safe to surrender the hw queue, as long as we could reapply
for polling later. For Synchronous polling, blk_poll() will reapply for
polling, since @spin is always True in this case. While For asynchronous
polling, i.e. io_uring itself will reapply for polling when the previous
polling returns 0.
Besides, it shall do no harm to the polling performance of mq devices.
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
drivers/nvme/host/pci.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 81e6389b2042..db164fcd04e2 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1106,7 +1106,9 @@ static int nvme_poll(struct blk_mq_hw_ctx *hctx)
if (!nvme_cqe_pending(nvmeq))
return 0;
- spin_lock(&nvmeq->cq_poll_lock);
+ if (!spin_trylock(&nvmeq->cq_poll_lock))
+ return 0;
+
found = nvme_process_cq(nvmeq);
spin_unlock(&nvmeq->cq_poll_lock);
--
2.27.0
next prev parent reply other threads:[~2021-02-20 11:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-20 11:06 [PATCH v4 00/12] dm: support IO polling Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 01/12] block: move definition of blk_qc_t to types.h Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 02/12] block: add queue_to_disk() to get gendisk from request_queue Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 03/12] block: add poll method to support bio-based IO polling Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 04/12] block: add poll_capable " Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 05/12] blk-mq: extract one helper function polling hw queue Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 06/12] blk-mq: add iterator for polling hw queues Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 07/12] blk-mq: add one helper function getting hw queue Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 08/12] dm: always return BLK_QC_T_NONE for bio-based device Jeffle Xu
2021-02-20 11:06 ` Jeffle Xu [this message]
2021-02-20 11:06 ` [PATCH v4 10/12] block: fastpath for bio-based polling Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 11/12] block: sub-fastpath " Jeffle Xu
2021-02-20 11:06 ` [PATCH v4 12/12] dm: support IO polling for bio-based dm device Jeffle Xu
2021-02-23 3:55 ` [PATCH v4 00/12] dm: support IO polling JeffleXu
2021-02-23 20:54 ` Mike Snitzer
2021-02-24 1:44 ` JeffleXu
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