From patchwork Wed Mar 3 11:57:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jingbo Xu X-Patchwork-Id: 12113879 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5330DC433E0 for ; Wed, 3 Mar 2021 16:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AEBE614A7 for ; Wed, 3 Mar 2021 16:43:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346861AbhCCQjA (ORCPT ); Wed, 3 Mar 2021 11:39:00 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:35837 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1442186AbhCCL6e (ORCPT ); Wed, 3 Mar 2021 06:58:34 -0500 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 Cc: io-uring@vger.kernel.org, dm-devel@redhat.com, linux-block@vger.kernel.org, mpatocka@redhat.com, caspar@linux.alibaba.com, joseph.qi@linux.alibaba.com Subject: [PATCH v5 09/12] nvme/pci: don't wait for locked polling queue Date: Wed, 3 Mar 2021 19:57:37 +0800 Message-Id: <20210303115740.127001-10-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210303115740.127001-1-jefflexu@linux.alibaba.com> References: <20210303115740.127001-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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);