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Wed, 03 Mar 2021 06:57:55 -0500 X-MC-Unique: 4zYcXWi0PfWcL1SjAFghbQ-1 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R331e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04400; MF=jefflexu@linux.alibaba.com; NM=1; PH=DS; RN=8; SR=0; TI=SMTPD_---0UQFBO9Y_1614772670 Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UQFBO9Y_1614772670) by smtp.aliyun-inc.com(127.0.0.1); Wed, 03 Mar 2021 19:57:50 +0800 From: Jeffle Xu To: msnitzer@redhat.com, axboe@kernel.dk Date: Wed, 3 Mar 2021 19:57:37 +0800 Message-Id: <20210303115740.127001-10-jefflexu@linux.alibaba.com> In-Reply-To: <20210303115740.127001-1-jefflexu@linux.alibaba.com> References: <20210303115740.127001-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Thu, 04 Mar 2021 09:41:43 -0500 Cc: caspar@linux.alibaba.com, linux-block@vger.kernel.org, joseph.qi@linux.alibaba.com, dm-devel@redhat.com, mpatocka@redhat.com, io-uring@vger.kernel.org Subject: [dm-devel] [PATCH v5 09/12] nvme/pci: don't wait for locked polling queue X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.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 --- 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 38b0d694dfc9..150e56ed6d15 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);