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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id AA9E0D462BF for ; Wed, 13 Nov 2024 15:21:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tk23PIrV2Cz7XbADe/d9c1pmhdDBEb+deIFGHOZfqPM=; b=Gdhtl5kzLsAS+1spNl3UCFp6hW x5gO68WhWthffLsb2nhYHTkjms3D4VTfHy5h5qnkwixnvExFuap46jFoAsRwWwwHMKzQ49MvfO+NU MB89eWFVK80zDv8tHrzVNiXqAqGmoM5pTTfhVIB7WN/7QdVK309HzTOQ3/SWcxQfNHHNk9O3MSh2u XHow1/5zPAz6Psu7YPbOrl3XvmDxnbsoXxhWO+WkZY8a8qgA84luIvEf18hU5x7PfJ1OVnHua6Yr3 O3LbaPI6Fnf3F4BBAXBtvCOE6FfcyciO6kOdHlJGGJzVkTrgt8W1JL5ilHvptnNQDOoaqihMYobg2 ZyV4J/WA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tBFAx-00000007HL5-01iU; Wed, 13 Nov 2024 15:20:59 +0000 Received: from 2a02-8389-2341-5b80-9e61-c6cf-2f07-a796.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:9e61:c6cf:2f07:a796] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tBFAu-00000007HJv-3oZb; Wed, 13 Nov 2024 15:20:57 +0000 From: Christoph Hellwig To: Jens Axboe Cc: "Michael S. Tsirkin" , Jason Wang , Keith Busch , Sagi Grimberg , Pavel Begunkov , linux-block@vger.kernel.org, virtualization@lists.linux.dev, linux-nvme@lists.infradead.org, io-uring@vger.kernel.org Subject: [PATCH 1/6] nvme-pci: reverse request order in nvme_queue_rqs Date: Wed, 13 Nov 2024 16:20:41 +0100 Message-ID: <20241113152050.157179-2-hch@lst.de> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20241113152050.157179-1-hch@lst.de> References: <20241113152050.157179-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org blk_mq_flush_plug_list submits requests in the reverse order that they were submitted, which leads to a rather suboptimal I/O pattern especially in rotational devices. Fix this by rewriting nvme_queue_rqs so that it always pops the requests from the passed in request list, and then adds them to the head of a local submit list. This actually simplifies the code a bit as it removes the complicated list splicing, at the cost of extra updates of the rq_next pointer. As that should be cache hot anyway it should be an easy price to pay. Fixes: d62cbcf62f2f ("nvme: add support for mq_ops->queue_rqs()") Signed-off-by: Christoph Hellwig --- drivers/nvme/host/pci.c | 39 +++++++++++++++++---------------------- 1 file changed, 17 insertions(+), 22 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 4b9fda0b1d9a..c66ea2c23690 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -904,9 +904,10 @@ static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx, static void nvme_submit_cmds(struct nvme_queue *nvmeq, struct request **rqlist) { + struct request *req; + spin_lock(&nvmeq->sq_lock); - while (!rq_list_empty(*rqlist)) { - struct request *req = rq_list_pop(rqlist); + while ((req = rq_list_pop(rqlist))) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); nvme_sq_copy_cmd(nvmeq, &iod->cmd); @@ -931,31 +932,25 @@ static bool nvme_prep_rq_batch(struct nvme_queue *nvmeq, struct request *req) static void nvme_queue_rqs(struct request **rqlist) { - struct request *req, *next, *prev = NULL; + struct request *submit_list = NULL; struct request *requeue_list = NULL; + struct request **requeue_lastp = &requeue_list; + struct nvme_queue *nvmeq = NULL; + struct request *req; - rq_list_for_each_safe(rqlist, req, next) { - struct nvme_queue *nvmeq = req->mq_hctx->driver_data; - - if (!nvme_prep_rq_batch(nvmeq, req)) { - /* detach 'req' and add to remainder list */ - rq_list_move(rqlist, &requeue_list, req, prev); - - req = prev; - if (!req) - continue; - } + while ((req = rq_list_pop(rqlist))) { + if (nvmeq && nvmeq != req->mq_hctx->driver_data) + nvme_submit_cmds(nvmeq, &submit_list); + nvmeq = req->mq_hctx->driver_data; - if (!next || req->mq_hctx != next->mq_hctx) { - /* detach rest of list, and submit */ - req->rq_next = NULL; - nvme_submit_cmds(nvmeq, rqlist); - *rqlist = next; - prev = NULL; - } else - prev = req; + if (nvme_prep_rq_batch(nvmeq, req)) + rq_list_add(&submit_list, req); /* reverse order */ + else + rq_list_add_tail(&requeue_lastp, req); } + if (nvmeq) + nvme_submit_cmds(nvmeq, &submit_list); *rqlist = requeue_list; } -- 2.45.2