From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E8852C43331 for ; Tue, 12 Nov 2019 18:11:50 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B4C072067B for ; Tue, 12 Nov 2019 18:11:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aDWRQ6nN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4C072067B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=n6YmWoJQzXqUWm6NNrEIk7iRMEIrF3CIMRXZOH5fVVY=; b=aDWRQ6nNsnDayaCqvpmHrUKcO GWvaNcWeePC6Sq0Ho1bRSw2DIE4Rl8Tiens6GrHmEHZjZ7y7dmmtMLTgs6y2ZiJi5crCar07e1yPa NJK4qEOmSOXogWbzKT5DZyybZhZfeAkli0tccY3SNciUf6hcQ5s/fUpklxJXi4KdvDA6rw1Ek5/Uf 7tL6zDqWuuKSHHzsSJfMC4S/2sMph1z8pVGqWliYqutKz8wnMgNPvaqSWEx5BWj7KblIaLmDTGhgW WIIhqg9B3mA7pn6ohKA2KvVLCC0Yz4+O3efAOv7x6exb/PkS7Kyh93IrCTC/d7OcRloD1YQWdexzz H1/Aa71Vg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUado-0007QJ-5m; Tue, 12 Nov 2019 18:11:48 +0000 Received: from mga18.intel.com ([134.134.136.126]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUadk-0007Po-HV for linux-nvme@lists.infradead.org; Tue, 12 Nov 2019 18:11:46 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Nov 2019 10:11:41 -0800 X-IronPort-AV: E=Sophos;i="5.68,297,1569308400"; d="scan'208";a="234965928" Received: from unknown (HELO [10.232.112.84]) ([10.232.112.84]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 12 Nov 2019 10:11:41 -0800 Subject: Re: [PATCH 2/2] nvme-pci: poll IO after batch submission for multi-mapping queue To: Ming Lei , linux-nvme@lists.infradead.org References: <20191108035508.26395-1-ming.lei@redhat.com> <20191108035508.26395-3-ming.lei@redhat.com> From: "Nadolski, Edmund" Message-ID: Date: Tue, 12 Nov 2019 11:11:40 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191108035508.26395-3-ming.lei@redhat.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191112_101144_633088_F1AA825C X-CRM114-Status: GOOD ( 29.91 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , Keith Busch , Long Li , Sagi Grimberg , Christoph Hellwig Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 11/7/2019 8:55 PM, Ming Lei wrote: > f9dde187fa92("nvme-pci: remove cq check after submission") removes > cq check after submission, this change actually causes performance > regression on some NVMe drive in which single nvmeq handles requests > originated from more than one blk-mq sw queues(call it multi-mapping > queue). > > Actually polling IO after submission can handle IO more efficiently, > especially for multi-mapping queue: > > 1) the poll itself is very cheap, and lockless check on cq is enough, > see nvme_cqe_pending(). Especially the check can be done after batch > submission is done. > > 2) when IO completion is observed via the poll in submission, the requst > may be completed without interrupt involved, or the interrupt handler > overload can be decreased. > > 3) when single sw queue is submiting IOs to this hw queue, if IOs completion > is observed via this poll, the IO can be completed locally, which is > cheaper than remote completion. > > Follows test result done on Azure L80sv2 guest with NVMe drive( > Microsoft Corporation Device b111). This guest has 80 CPUs and 10 > numa nodes, and each NVMe drive supports 8 hw queues. > > 1) test script: > fio --bs=4k --ioengine=libaio --iodepth=64 --filename=/dev/nvme0n1 \ > --iodepth_batch_submit=16 --iodepth_batch_complete_min=16 \ > --direct=1 --runtime=30 --numjobs=1 --rw=randread \ > --name=test --group_reporting --gtod_reduce=1 > > 2) test result: > | v5.3 | v5.3 with this patchset > ------------------------------------------- > IOPS | 130K | 424K > > Given IO is handled more efficiently in this way, the original report > of CPU lockup[1] on Hyper-V can't be observed any more after this patch > is applied. This issue is usually triggered when running IO from all > CPUs concurrently. > > I also run test on Optane(32 hw queues) in big machine(96 cores, 2 numa > nodes), small improvement is observed on running the above fio over two > NVMe drive with batch 1. > > [1] https://lore.kernel.org/lkml/1566281669-48212-1-git-send-email-longli@linuxonhyperv.com > > Cc: Keith Busch > Cc: Jens Axboe > Cc: Christoph Hellwig > Cc: Sagi Grimberg > Cc: Long Li > Fixes: f9dde187fa92("nvme-pci: remove cq check after submission") > Signed-off-by: Ming Lei > --- > drivers/nvme/host/pci.c | 90 ++++++++++++++++++++++++++++++++++++----- > 1 file changed, 80 insertions(+), 10 deletions(-) > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 5b20ab4d21d3..880376f43897 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -83,6 +83,7 @@ struct nvme_queue; > > static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown); > static bool __nvme_disable_io_queues(struct nvme_dev *dev, u8 opcode); > +static void nvme_poll_in_submission(struct nvme_queue *nvmeq); > > /* > * Represents an NVM Express device. Each nvme_dev is a PCI function. > @@ -165,7 +166,10 @@ struct nvme_queue { > spinlock_t sq_lock; > void *sq_cmds; > /* only used for poll queues: */ > - spinlock_t cq_poll_lock ____cacheline_aligned_in_smp; > + union { > + spinlock_t cq_poll_lock; > + spinlock_t cq_lock; > + }____cacheline_aligned_in_smp; Is the new lock intended to protect anything differently than the old lock? > volatile struct nvme_completion *cqes; > struct blk_mq_tags **tags; > dma_addr_t sq_dma_addr; > @@ -185,6 +189,7 @@ struct nvme_queue { > #define NVMEQ_SQ_CMB 1 > #define NVMEQ_DELETE_ERROR 2 > #define NVMEQ_POLLED 3 > +#define NVMEQ_MULTI_MAPPING 4 > u32 *dbbuf_sq_db; > u32 *dbbuf_cq_db; > u32 *dbbuf_sq_ei; > @@ -911,6 +916,10 @@ static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx, > > blk_mq_start_request(req); > nvme_submit_cmd(nvmeq, &cmnd, bd->last); > + > + if (bd->last) > + nvme_poll_in_submission(nvmeq); > + > return BLK_STS_OK; > out_unmap_data: > nvme_unmap_data(dev, req); > @@ -1016,6 +1025,19 @@ static inline int nvme_process_cq(struct nvme_queue *nvmeq, u16 *start, > return found; > } > > +static inline irqreturn_t > +nvme_update_cq(struct nvme_queue *nvmeq, u16 *start, u16 *end) > +{ > + irqreturn_t ret = IRQ_NONE; > + > + if (nvmeq->cq_head != nvmeq->last_cq_head) > + ret = IRQ_HANDLED; > + nvme_process_cq(nvmeq, start, end, -1); > + nvmeq->last_cq_head = nvmeq->cq_head; > + > + return ret; > +} > + > static irqreturn_t nvme_irq(int irq, void *data) > { > struct nvme_queue *nvmeq = data; > @@ -1027,10 +1049,7 @@ static irqreturn_t nvme_irq(int irq, void *data) > * the irq handler, even if that was on another CPU. > */ > rmb(); > - if (nvmeq->cq_head != nvmeq->last_cq_head) > - ret = IRQ_HANDLED; > - nvme_process_cq(nvmeq, &start, &end, -1); > - nvmeq->last_cq_head = nvmeq->cq_head; > + ret = nvme_update_cq(nvmeq, &start, &end); > wmb(); > > if (start != end) { > @@ -1041,6 +1060,24 @@ static irqreturn_t nvme_irq(int irq, void *data) > return ret; > } > > +static irqreturn_t nvme_irq_multi_mapping(int irq, void *data) > +{ > + struct nvme_queue *nvmeq = data; > + irqreturn_t ret = IRQ_NONE; > + u16 start, end; > + > + spin_lock(&nvmeq->cq_lock); > + ret = nvme_update_cq(nvmeq, &start, &end); > + spin_unlock(&nvmeq->cq_lock); > + > + if (start != end) { > + nvme_complete_cqes(nvmeq, start, end); > + return IRQ_HANDLED; > + } > + > + return ret; > +} > + > static irqreturn_t nvme_irq_check(int irq, void *data) > { > struct nvme_queue *nvmeq = data; > @@ -1049,6 +1086,24 @@ static irqreturn_t nvme_irq_check(int irq, void *data) > return IRQ_NONE; > } > > +static void nvme_poll_in_submission(struct nvme_queue *nvmeq) > +{ > + if (test_bit(NVMEQ_MULTI_MAPPING, &nvmeq->flags) && > + nvme_cqe_pending(nvmeq)) { > + unsigned long flags; > + > + if (spin_trylock_irqsave(&nvmeq->cq_lock, flags)) { > + u16 start, end; > + > + nvme_update_cq(nvmeq, &start, &end); > + spin_unlock_irqrestore(&nvmeq->cq_lock, flags); > + > + if (start != end) > + nvme_complete_cqes(nvmeq, start, end); > + } > + } > +} Just a nit, to me it reads simpler to return right away when the first test is false, rather than enclose the true path in an additional nesting level. Thanks, Ed > /* > * Poll for completions any queue, including those not dedicated to polling. > * Can be called from any context. > @@ -1499,12 +1554,14 @@ static int queue_request_irq(struct nvme_queue *nvmeq) > { > struct pci_dev *pdev = to_pci_dev(nvmeq->dev->dev); > int nr = nvmeq->dev->ctrl.instance; > + irq_handler_t handler = test_bit(NVMEQ_MULTI_MAPPING, &nvmeq->flags) ? > + nvme_irq_multi_mapping : nvme_irq; > > if (use_threaded_interrupts) { > return pci_request_irq(pdev, nvmeq->cq_vector, nvme_irq_check, > - nvme_irq, nvmeq, "nvme%dq%d", nr, nvmeq->qid); > + handler, nvmeq, "nvme%dq%d", nr, nvmeq->qid); > } else { > - return pci_request_irq(pdev, nvmeq->cq_vector, nvme_irq, > + return pci_request_irq(pdev, nvmeq->cq_vector, handler, > NULL, nvmeq, "nvme%dq%d", nr, nvmeq->qid); > } > } > @@ -1514,7 +1571,13 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid) > struct nvme_dev *dev = nvmeq->dev; > > spin_lock_init(&nvmeq->sq_lock); > - spin_lock_init(&nvmeq->cq_poll_lock); > + > + if (test_bit(NVMEQ_MULTI_MAPPING, &nvmeq->flags)) { > + WARN_ON_ONCE(test_bit(NVMEQ_POLLED, &nvmeq->flags)); > + spin_lock_init(&nvmeq->cq_lock); > + } else { > + spin_lock_init(&nvmeq->cq_poll_lock); > + } > > nvmeq->sq_tail = 0; > nvmeq->last_sq_tail = 0; > @@ -1534,15 +1597,22 @@ static int nvme_create_queue(struct nvme_queue *nvmeq, int qid, bool polled) > u16 vector = 0; > > clear_bit(NVMEQ_DELETE_ERROR, &nvmeq->flags); > + clear_bit(NVMEQ_MULTI_MAPPING, &nvmeq->flags); > > /* > * A queue's vector matches the queue identifier unless the controller > * has only one vector available. > */ > - if (!polled) > + if (!polled) { > + struct pci_dev *pdev = to_pci_dev(dev->dev); > + > vector = dev->num_vecs == 1 ? 0 : qid; > - else > + if (vector && cpumask_weight(pci_irq_get_affinity(pdev, > + vector)) > 1) > + set_bit(NVMEQ_MULTI_MAPPING, &nvmeq->flags); > + } else { > set_bit(NVMEQ_POLLED, &nvmeq->flags); > + } > > result = adapter_alloc_cq(dev, qid, nvmeq, vector); > if (result) > _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme