From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 829E71474AF; Fri, 6 Dec 2024 14:53:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733496800; cv=none; b=cRy+B+etmdKPmEiQroQ83aIZ6/po4oQdSZ6OurB+ErqrXJDgVgY5gY4Nq8PIQWuB0zeISjWsO+N9ouE4x1IiloQvutW2P2ezHc+k5T52yF/6nS1YUAV1bLDaJfGC1LDJKmDRUoSbzYDmbftL3ZQbk1ZvptYWwTe9O0GNazMhjVw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733496800; c=relaxed/simple; bh=ivzRKYymRTj1iaHgmwuXsRGbCZa6yqJ/Pwz78Auq9SI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gfW+SpWbaDfum8REsQgOwJlYEL+FTXGaffijWj0Gatt7g5agLGm7/pyJRnVSzLLk07Fll6FaGJCtL7o8v/iSVwVJAyuP05VN4CtTYSBqsDiQBxTG5ilV/1eLjPF7ovfxXHH7V78G7rEh+z6dIzKWE/tD24PxvJaWPsorKeKyKm0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gmCrTKnQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gmCrTKnQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E60BFC4CED1; Fri, 6 Dec 2024 14:53:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1733496800; bh=ivzRKYymRTj1iaHgmwuXsRGbCZa6yqJ/Pwz78Auq9SI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gmCrTKnQQ8ZqIoqv36CtCWpSeM2MDYfJm/ZqEdhylps8zm/JaGdWnDoIENV5lBdIJ YxkHwtF+hkZGuwLtml7Wok07pumKbr3Hmqb2PVbsbhLIWLaI1HKrMk2OAiNuPvG+VI sDpp6YG7uelCIoeGCj86ioqQTS65zVm6gb0J2iMU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christoph Hellwig , Jens Axboe , Sasha Levin Subject: [PATCH 6.6 076/676] virtio_blk: reverse request order in virtio_queue_rqs Date: Fri, 6 Dec 2024 15:28:15 +0100 Message-ID: <20241206143656.338463813@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241206143653.344873888@linuxfoundation.org> References: <20241206143653.344873888@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Hellwig [ Upstream commit 7f212e997edbb7a2cb85cef2ac14265dfaf88717 ] 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 virtio_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: 0e9911fa768f ("virtio-blk: support mq_ops->queue_rqs()") Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20241113152050.157179-3-hch@lst.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/virtio_blk.c | 46 +++++++++++++++++--------------------- 1 file changed, 21 insertions(+), 25 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 41b2fd7e1b9e5..997106fe73e49 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -475,18 +475,18 @@ static bool virtblk_prep_rq_batch(struct request *req) return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK; } -static bool virtblk_add_req_batch(struct virtio_blk_vq *vq, +static void virtblk_add_req_batch(struct virtio_blk_vq *vq, struct request **rqlist) { + struct request *req; unsigned long flags; - int err; bool kick; spin_lock_irqsave(&vq->lock, flags); - while (!rq_list_empty(*rqlist)) { - struct request *req = rq_list_pop(rqlist); + while ((req = rq_list_pop(rqlist))) { struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); + int err; err = virtblk_add_req(vq->vq, vbr); if (err) { @@ -499,37 +499,33 @@ static bool virtblk_add_req_batch(struct virtio_blk_vq *vq, kick = virtqueue_kick_prepare(vq->vq); spin_unlock_irqrestore(&vq->lock, flags); - return kick; + if (kick) + virtqueue_notify(vq->vq); } static void virtio_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 virtio_blk_vq *vq = NULL; + struct request *req; - rq_list_for_each_safe(rqlist, req, next) { - struct virtio_blk_vq *vq = get_virtio_blk_vq(req->mq_hctx); - bool kick; - - if (!virtblk_prep_rq_batch(req)) { - rq_list_move(rqlist, &requeue_list, req, prev); - req = prev; - if (!req) - continue; - } + while ((req = rq_list_pop(rqlist))) { + struct virtio_blk_vq *this_vq = get_virtio_blk_vq(req->mq_hctx); - if (!next || req->mq_hctx != next->mq_hctx) { - req->rq_next = NULL; - kick = virtblk_add_req_batch(vq, rqlist); - if (kick) - virtqueue_notify(vq->vq); + if (vq && vq != this_vq) + virtblk_add_req_batch(vq, &submit_list); + vq = this_vq; - *rqlist = next; - prev = NULL; - } else - prev = req; + if (virtblk_prep_rq_batch(req)) + rq_list_add(&submit_list, req); /* reverse order */ + else + rq_list_add_tail(&requeue_lastp, req); } + if (vq) + virtblk_add_req_batch(vq, &submit_list); *rqlist = requeue_list; } -- 2.43.0