From patchwork Thu Mar 24 14:04:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suwan Kim X-Patchwork-Id: 12790720 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 264FFC433F5 for ; Thu, 24 Mar 2022 14:05:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344334AbiCXOHK (ORCPT ); Thu, 24 Mar 2022 10:07:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231871AbiCXOHJ (ORCPT ); Thu, 24 Mar 2022 10:07:09 -0400 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E0F86CA63 for ; Thu, 24 Mar 2022 07:05:37 -0700 (PDT) Received: by mail-pl1-x635.google.com with SMTP id y6so2248990plg.2 for ; Thu, 24 Mar 2022 07:05:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=u9NKBaWZds0RIS9nv+EyJu20fE5vPp3DVac/rH4x2sU=; b=KBNiUWKmOhhW+kSkvmVauw2dPX8HY7bYI+QcYNaakM9XaRMRlr+RpemsSJQ1l0+UFG biSY6TOrmNe0gBSMDPHM5fseqHUbTQnOS2YFxNoGbKPh2NUEJEu1yZWrYgj3oTqiPOOV 25oCkWPCF9+4YaiHb4GsbarLWizLyABT+ur8hY4ISK5jTCtPAekp598c+Bzbg65K9d8i H2A5u4QDul9TKbCRvNg6Ntedq8dWK3R/zIywTdo7VjRbRmaTgAwaUBSXs4suwZdeeMFw aRyoZpfCOhXH45sSqJ+IEGMh7isRabFSdYCwg8O46AxtGcZ99qSFDpfPgdfX2/W5ijIl cQ7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=u9NKBaWZds0RIS9nv+EyJu20fE5vPp3DVac/rH4x2sU=; b=lcE9+DWVDj2LLi4RizjmBbZoS8hFF1Uq+ueShvXVBpMC72lDrfhFafTgodej5CgfPL 7KNTlCKSr8aP91lsauksThBtNbfapN1XJpzmHgCrfZua0Dqxc5VgkSPZAHW8XAz4DmA6 7ePFAwZcr9WL7q/RadBd5yXzAlh6fjzaUelawmLMOzzGzQIpzRHpnwaTRRBFRiy463z1 TNSIXh4QVY7MOkVHA8gXCtNch+Sg4jye6MFjBwMU4PpwboWbBtYAUydBjKkUD7Li1tm8 NsT4pcKV3+4Dtl8MRu1nE2Qajb3FdWvhU+WZ84bIpuACtLQnkJLrm93KDfAEo1ZGT85H YGXQ== X-Gm-Message-State: AOAM533K2ZqhtTSkfwS0wKWPvWrXQ5LnhPFHT8xXxYpKP++zjFmB8UwA U22VcjAwqqU05zDephSvSvBEDc2lSHwQnw== X-Google-Smtp-Source: ABdhPJw3Ni+KJ63WvOlcO5Yx5kJqLa5aQDXyvXny86PZU6L9FfkZxfuKx2A7aWzMyIbTy6bnQ8Z8mQ== X-Received: by 2002:a17:902:ba8c:b0:14f:d9b7:ab4 with SMTP id k12-20020a170902ba8c00b0014fd9b70ab4mr6109036pls.23.1648130736552; Thu, 24 Mar 2022 07:05:36 -0700 (PDT) Received: from localhost.localdomain ([114.200.4.15]) by smtp.googlemail.com with ESMTPSA id u12-20020a17090a890c00b001b8efcf8e48sm9441845pjn.14.2022.03.24.07.05.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Mar 2022 07:05:35 -0700 (PDT) From: Suwan Kim To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, mgurtovoy@nvidia.com Cc: virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, Suwan Kim , kernel test robot Subject: [PATCH v3 1/2] virtio-blk: support polling I/O Date: Thu, 24 Mar 2022 23:04:49 +0900 Message-Id: <20220324140450.33148-2-suwan.kim027@gmail.com> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20220324140450.33148-1-suwan.kim027@gmail.com> References: <20220324140450.33148-1-suwan.kim027@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This patch supports polling I/O via virtio-blk driver. Polling feature is enabled by module parameter "num_poll_queues" and it sets dedicated polling queues for virtio-blk. This patch improves the polling I/O throughput and latency. The virtio-blk driver doesn't not have a poll function and a poll queue and it has been operating in interrupt driven method even if the polling function is called in the upper layer. virtio-blk polling is implemented upon 'batched completion' of block layer. virtblk_poll() queues completed request to io_comp_batch->req_list and later, virtblk_complete_batch() calls unmap function and ends the requests in batch. virtio-blk reads the number of poll queues from module parameter "num_poll_queues". If VM sets queue parameter as below, ("num-queues=N" [QEMU property], "num_poll_queues=M" [module parameter]) It allocates N virtqueues to virtio_blk->vqs[N] and it uses [0..(N-M-1)] as default queues and [(N-M)..(N-1)] as poll queues. Unlike the default queues, the poll queues have no callback function. Regarding HW-SW queue mapping, the default queue mapping uses the existing method that condsiders MSI irq vector. But the poll queue doesn't have an irq, so it uses the regular blk-mq cpu mapping. For verifying the improvement, I did Fio polling I/O performance test with io_uring engine with the options below. (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=N) I set 4 vcpu and 4 virtio-blk queues - 2 default queues and 2 poll queues for VM. As a result, IOPS and average latency improved about 10%. Test result: - Fio io_uring poll without virtio-blk poll support -- numjobs=1 : IOPS = 339K, avg latency = 188.33us -- numjobs=2 : IOPS = 367K, avg latency = 347.33us -- numjobs=4 : IOPS = 383K, avg latency = 682.06us - Fio io_uring poll with virtio-blk poll support -- numjobs=1 : IOPS = 380K, avg latency = 167.87us -- numjobs=2 : IOPS = 409K, avg latency = 312.6us -- numjobs=4 : IOPS = 413K, avg latency = 619.72us Reported-by: kernel test robot Signed-off-by: Suwan Kim --- drivers/block/virtio_blk.c | 101 +++++++++++++++++++++++++++++++++++-- 1 file changed, 97 insertions(+), 4 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 8c415be86732..3d16f8b753e7 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -37,6 +37,10 @@ MODULE_PARM_DESC(num_request_queues, "0 for no limit. " "Values > nr_cpu_ids truncated to nr_cpu_ids."); +static unsigned int num_poll_queues; +module_param(num_poll_queues, uint, 0644); +MODULE_PARM_DESC(num_poll_queues, "The number of dedicated virtqueues for polling I/O"); + static int major; static DEFINE_IDA(vd_index_ida); @@ -81,6 +85,7 @@ struct virtio_blk { /* num of vqs */ int num_vqs; + int io_queues[HCTX_MAX_TYPES]; struct virtio_blk_vq *vqs; }; @@ -548,6 +553,7 @@ static int init_vq(struct virtio_blk *vblk) const char **names; struct virtqueue **vqs; unsigned short num_vqs; + unsigned int num_poll_vqs; struct virtio_device *vdev = vblk->vdev; struct irq_affinity desc = { 0, }; @@ -556,6 +562,7 @@ static int init_vq(struct virtio_blk *vblk) &num_vqs); if (err) num_vqs = 1; + if (!err && !num_vqs) { dev_err(&vdev->dev, "MQ advertised but zero queues reported\n"); return -EINVAL; @@ -565,6 +572,13 @@ static int init_vq(struct virtio_blk *vblk) min_not_zero(num_request_queues, nr_cpu_ids), num_vqs); + num_poll_vqs = min_t(unsigned int, num_poll_queues, num_vqs - 1); + + memset(vblk->io_queues, 0, sizeof(int) * HCTX_MAX_TYPES); + vblk->io_queues[HCTX_TYPE_DEFAULT] = num_vqs - num_poll_vqs; + vblk->io_queues[HCTX_TYPE_READ] = 0; + vblk->io_queues[HCTX_TYPE_POLL] = num_poll_vqs; + vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL); if (!vblk->vqs) return -ENOMEM; @@ -578,8 +592,13 @@ static int init_vq(struct virtio_blk *vblk) } for (i = 0; i < num_vqs; i++) { - callbacks[i] = virtblk_done; - snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i); + if (i < num_vqs - num_poll_vqs) { + callbacks[i] = virtblk_done; + snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i); + } else { + callbacks[i] = NULL; + snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req_poll.%d", i); + } names[i] = vblk->vqs[i].name; } @@ -728,16 +747,87 @@ static const struct attribute_group *virtblk_attr_groups[] = { static int virtblk_map_queues(struct blk_mq_tag_set *set) { struct virtio_blk *vblk = set->driver_data; + int i, qoff; + + for (i = 0, qoff = 0; i < set->nr_maps; i++) { + struct blk_mq_queue_map *map = &set->map[i]; + + map->nr_queues = vblk->io_queues[i]; + map->queue_offset = qoff; + qoff += map->nr_queues; + + if (map->nr_queues == 0) + continue; + + /* + * Regular queues have interrupts and hence CPU affinity is + * defined by the core virtio code, but polling queues have + * no interrupts so we let the block layer assign CPU affinity. + */ + if (i == HCTX_TYPE_DEFAULT) + blk_mq_virtio_map_queues(&set->map[i], vblk->vdev, 0); + else + blk_mq_map_queues(&set->map[i]); + } + + return 0; +} + +static void virtblk_complete_batch(struct io_comp_batch *iob) +{ + struct request *req; + struct virtblk_req *vbr; - return blk_mq_virtio_map_queues(&set->map[HCTX_TYPE_DEFAULT], - vblk->vdev, 0); + rq_list_for_each(&iob->req_list, req) { + vbr = blk_mq_rq_to_pdu(req); + virtblk_unmap_data(req, vbr); + virtblk_cleanup_cmd(req); + } + blk_mq_end_request_batch(iob); +} + +static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob) +{ + struct virtio_blk_vq *vq = hctx->driver_data; + struct virtblk_req *vbr; + unsigned long flags; + unsigned int len; + int found = 0; + + spin_lock_irqsave(&vq->lock, flags); + + while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) { + struct request *req = blk_mq_rq_from_pdu(vbr); + + found++; + if (!blk_mq_add_to_batch(req, iob, vbr->status, + virtblk_complete_batch)) + blk_mq_complete_request(req); + } + + spin_unlock_irqrestore(&vq->lock, flags); + + return found; +} + +static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, + unsigned int hctx_idx) +{ + struct virtio_blk *vblk = data; + struct virtio_blk_vq *vq = &vblk->vqs[hctx_idx]; + + WARN_ON(vblk->tag_set.tags[hctx_idx] != hctx->tags); + hctx->driver_data = vq; + return 0; } static const struct blk_mq_ops virtio_mq_ops = { .queue_rq = virtio_queue_rq, .commit_rqs = virtio_commit_rqs, + .init_hctx = virtblk_init_hctx, .complete = virtblk_request_done, .map_queues = virtblk_map_queues, + .poll = virtblk_poll, }; static unsigned int virtblk_queue_depth; @@ -816,6 +906,9 @@ static int virtblk_probe(struct virtio_device *vdev) sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT; vblk->tag_set.driver_data = vblk; vblk->tag_set.nr_hw_queues = vblk->num_vqs; + vblk->tag_set.nr_maps = 1; + if (vblk->io_queues[HCTX_TYPE_POLL]) + vblk->tag_set.nr_maps = 3; err = blk_mq_alloc_tag_set(&vblk->tag_set); if (err) From patchwork Thu Mar 24 14:04:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suwan Kim X-Patchwork-Id: 12790721 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57669C433EF for ; Thu, 24 Mar 2022 14:05:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350736AbiCXOHZ (ORCPT ); Thu, 24 Mar 2022 10:07:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350735AbiCXOHU (ORCPT ); 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Thu, 24 Mar 2022 07:05:46 -0700 (PDT) From: Suwan Kim To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, mgurtovoy@nvidia.com Cc: virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, Suwan Kim Subject: [PATCH v3 2/2] virtio-blk: support mq_ops->queue_rqs() Date: Thu, 24 Mar 2022 23:04:50 +0900 Message-Id: <20220324140450.33148-3-suwan.kim027@gmail.com> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20220324140450.33148-1-suwan.kim027@gmail.com> References: <20220324140450.33148-1-suwan.kim027@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This patch supports mq_ops->queue_rqs() hook. It has an advantage of batch submission to virtio-blk driver. It also helps polling I/O because polling uses batched completion of block layer. Batch submission in queue_rqs() can boost polling performance. In queue_rqs(), it iterates plug->mq_list, collects requests that belong to same HW queue and adds requests into virtqueue until it encounters a request from other HW queue or sees the end of the list. Then, virtio-blk kicks virtqueue to submit requests. If there is an error, it inserts error request to requeue_list and passes it to ordinary block layer path. For verification, I did fio test. (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. It shows about 1-4% improvement. | numjobs=2 | numjobs=4 ----------------------------------------------------------- fio without queue_rqs() | 282K IOPS | 245K IOPS ----------------------------------------------------------- fio with queue_rqs() | 294K IOPS | 249K IOPS For polling I/O performance, I also did fio test as below. (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) I set 4 vcpu and 2 poll queues for VM. It shows upto 7% improvement in polling I/O. | IOPS | avg latency ----------------------------------------------------------- fio poll without queue_rqs() | 413K | 619.72 usec ----------------------------------------------------------- fio poll with queue_rqs() | 445K | 581.2 usec Signed-off-by: Suwan Kim --- drivers/block/virtio_blk.c | 93 ++++++++++++++++++++++++++++++++++---- 1 file changed, 84 insertions(+), 9 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 3d16f8b753e7..4a0a3b2d9caf 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -311,6 +311,28 @@ static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx) virtqueue_notify(vq->vq); } +static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx, + struct virtio_blk *vblk, + struct request *req, + struct virtblk_req *vbr, int *num) +{ + blk_status_t status; + + status = virtblk_setup_cmd(vblk->vdev, req, vbr); + if (unlikely(status)) + return status; + + blk_mq_start_request(req); + + *num = virtblk_map_data(hctx, req, vbr); + if (unlikely(*num < 0)) { + virtblk_cleanup_cmd(req); + return BLK_STS_RESOURCE; + } + + return BLK_STS_OK; +} + static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { @@ -324,18 +346,10 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, blk_status_t status; int err; - status = virtblk_setup_cmd(vblk->vdev, req, vbr); + status = virtblk_prep_rq(hctx, vblk, req, vbr, &num); if (unlikely(status)) return status; - blk_mq_start_request(req); - - num = virtblk_map_data(hctx, req, vbr); - if (unlikely(num < 0)) { - virtblk_cleanup_cmd(req); - return BLK_STS_RESOURCE; - } - spin_lock_irqsave(&vblk->vqs[qid].lock, flags); err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num); if (err) { @@ -367,6 +381,66 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, return BLK_STS_OK; } +static bool virtblk_prep_rq_batch(struct virtio_blk_vq *vq, struct request *req) +{ + struct virtio_blk *vblk = req->mq_hctx->queue->queuedata; + struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); + unsigned long flags; + int num, err; + + req->mq_hctx->tags->rqs[req->tag] = req; + + if (virtblk_prep_rq(req->mq_hctx, vblk, req, vbr, &num) != BLK_STS_OK) + return false; + + spin_lock_irqsave(&vq->lock, flags); + err = virtblk_add_req(vq->vq, vbr, vbr->sg_table.sgl, num); + if (err) { + spin_unlock_irqrestore(&vq->lock, flags); + virtblk_unmap_data(req, vbr); + virtblk_cleanup_cmd(req); + return false; + } + spin_unlock_irqrestore(&vq->lock, flags); + + return true; +} + +static void virtio_queue_rqs(struct request **rqlist) +{ + struct request *req, *next, *prev = NULL; + struct request *requeue_list = NULL; + + rq_list_for_each_safe(rqlist, req, next) { + struct virtio_blk_vq *vq = req->mq_hctx->driver_data; + unsigned long flags; + bool kick; + + if (!virtblk_prep_rq_batch(vq, req)) { + rq_list_move(rqlist, &requeue_list, req, prev); + req = prev; + + if (!req) + continue; + } + + if (!next || req->mq_hctx != next->mq_hctx) { + spin_lock_irqsave(&vq->lock, flags); + kick = virtqueue_kick_prepare(vq->vq); + spin_unlock_irqrestore(&vq->lock, flags); + if (kick) + virtqueue_notify(vq->vq); + + req->rq_next = NULL; + *rqlist = next; + prev = NULL; + } else + prev = req; + } + + *rqlist = requeue_list; +} + /* return id (s/n) string for *disk to *id_str */ static int virtblk_get_id(struct gendisk *disk, char *id_str) @@ -823,6 +897,7 @@ static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, static const struct blk_mq_ops virtio_mq_ops = { .queue_rq = virtio_queue_rq, + .queue_rqs = virtio_queue_rqs, .commit_rqs = virtio_commit_rqs, .init_hctx = virtblk_init_hctx, .complete = virtblk_request_done,