From patchwork Tue Nov 26 09:14:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hannes Reinecke X-Patchwork-Id: 11261679 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1DDE014ED for ; Tue, 26 Nov 2019 09:14:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00A682073F for ; Tue, 26 Nov 2019 09:14:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727495AbfKZJO3 (ORCPT ); Tue, 26 Nov 2019 04:14:29 -0500 Received: from mx2.suse.de ([195.135.220.15]:41592 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727452AbfKZJO1 (ORCPT ); Tue, 26 Nov 2019 04:14:27 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8F555BA0B; Tue, 26 Nov 2019 09:14:23 +0000 (UTC) From: Hannes Reinecke To: "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , Ming Lei , Bart van Assche , John Garry , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Hannes Reinecke Subject: [PATCH 4/8] blk-mq: Facilitate a shared sbitmap per tagset Date: Tue, 26 Nov 2019 10:14:12 +0100 Message-Id: <20191126091416.20052-5-hare@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20191126091416.20052-1-hare@suse.de> References: <20191126091416.20052-1-hare@suse.de> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: John Garry Some SCSI HBAs (such as HPSA, megaraid, mpt3sas, hisi_sas_v3 ..) support multiple reply queues with single hostwide tags. In addition, these drivers want to use interrupt assignment in pci_alloc_irq_vectors(PCI_IRQ_AFFINITY). However, as discussed in [0], CPU hotplug may cause in-flight IO completion to not be serviced when an interrupt is shutdown. To solve that problem, Ming's patchset to drain hctx's should ensure no IOs are missed in-flight [1]. However, to take advantage of that patchset, we need to map the HBA HW queues to blk mq hctx's; to do that, we need to expose the HBA HW queues. In making that transition, the per-SCSI command request tags are no longer unique per Scsi host - they are just unique per hctx. As such, the HBA LLDD would have to generate this tag internally, which has a certain performance overhead. However another problem is that blk mq assumes the host may accept (Scsi_host.can_queue * #hw queue) commands. In [2], we removed the Scsi host busy counter, which would stop the LLDD being sent more than .can_queue commands; however, we should still ensure that the block layer does not issue more than .can_queue commands to the Scsi host. To solve this problem, introduce a shared sbitmap per blk_mq_tag_set, which may be requested at init time. New flag BLK_MQ_F_TAG_HCTX_SHARED should be set when requesting the tagset to indicate whether the shared sbitmap should be used. Even when BLK_MQ_F_TAG_HCTX_SHARED is set, we still allocate a full set of tags and requests per hctx; the reason for this is that if we only allocate tags and requests for a single hctx - like hctx0 - we may break block drivers which expect a request be associated with a specific hctx, i.e. not hctx0. This is based on work originally from Ming Lei in [3] and from Bart's suggestion in [4]. [0] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ [1] https://lore.kernel.org/linux-block/20191014015043.25029-1-ming.lei@redhat.com/ [2] https://lore.kernel.org/linux-scsi/20191025065855.6309-1-ming.lei@redhat.com/ [3] https://lore.kernel.org/linux-block/20190531022801.10003-1-ming.lei@redhat.com/ [4] https://lore.kernel.org/linux-block/ff77beff-5fd9-9f05-12b6-826922bace1f@huawei.com/T/#m3db0a602f095cbcbff27e9c884d6b4ae826144be Signed-off-by: John Garry Signed-off-by: Hannes Reinecke --- block/blk-mq-sched.c | 8 ++++++-- block/blk-mq-tag.c | 36 +++++++++++++++++++++++++++++------- block/blk-mq-tag.h | 6 +++++- block/blk-mq.c | 45 ++++++++++++++++++++++++++++++++++++--------- block/blk-mq.h | 7 ++++++- include/linux/blk-mq.h | 7 +++++++ 6 files changed, 89 insertions(+), 20 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index ca22afd47b3d..f3589f42b96d 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -452,7 +452,7 @@ static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set, { if (hctx->sched_tags) { blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx); - blk_mq_free_rq_map(hctx->sched_tags); + blk_mq_free_rq_map(hctx->sched_tags, false); hctx->sched_tags = NULL; } } @@ -462,10 +462,14 @@ static int blk_mq_sched_alloc_tags(struct request_queue *q, unsigned int hctx_idx) { struct blk_mq_tag_set *set = q->tag_set; + int flags = set->flags; int ret; + /* Scheduler tags are never shared */ + set->flags &= ~BLK_MQ_F_TAG_HCTX_SHARED; hctx->sched_tags = blk_mq_alloc_rq_map(set, hctx_idx, q->nr_requests, set->reserved_tags); + set->flags = flags; if (!hctx->sched_tags) return -ENOMEM; @@ -484,7 +488,7 @@ static void blk_mq_sched_tags_teardown(struct request_queue *q) queue_for_each_hw_ctx(q, hctx, i) { if (hctx->sched_tags) { - blk_mq_free_rq_map(hctx->sched_tags); + blk_mq_free_rq_map(hctx->sched_tags, false); hctx->sched_tags = NULL; } } diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 332d71cd3976..53b4c4c53c6a 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -228,7 +228,7 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) * We can hit rq == NULL here, because the tagging functions * test and set the bit before assigning ->rqs[]. */ - if (rq && rq->q == hctx->queue) + if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) return iter_data->fn(hctx, rq, iter_data->data, reserved); return true; } @@ -470,7 +470,27 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, return -ENOMEM; } -struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, +bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set) +{ + unsigned int depth = tag_set->queue_depth -tag_set->reserved_tags; + int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(tag_set->flags); + bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; + int node = tag_set->numa_node; + + if (bt_alloc(&tag_set->shared_bitmap_tags, depth, round_robin, node)) + return false; + if (bt_alloc(&tag_set->shared_breserved_tags, tag_set->reserved_tags, round_robin, + node)) + goto free_bitmap_tags; + + return true; +free_bitmap_tags: + sbitmap_queue_free(&tag_set->shared_bitmap_tags); + return false; +} + +struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *set, + unsigned int total_tags, unsigned int reserved_tags, int node, int alloc_policy) { @@ -488,9 +508,11 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, tags->nr_tags = total_tags; tags->nr_reserved_tags = reserved_tags; - if (blk_mq_init_bitmap_tags(tags, node, alloc_policy) < 0) { - kfree(tags); - tags = NULL; + if (!blk_mq_is_sbitmap_shared(set)) { + if (blk_mq_init_bitmap_tags(tags, node, alloc_policy) < 0) { + kfree(tags); + tags = NULL; + } } return tags; } @@ -538,12 +560,12 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, return -ENOMEM; ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth); if (ret) { - blk_mq_free_rq_map(new); + blk_mq_free_rq_map(new, blk_mq_is_sbitmap_shared(set)); return -ENOMEM; } blk_mq_free_rqs(set, *tagsptr, hctx->queue_num); - blk_mq_free_rq_map(*tagsptr); + blk_mq_free_rq_map(*tagsptr, blk_mq_is_sbitmap_shared(set)); *tagsptr = new; } else { /* diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index 10b66fd4664a..279a861c7e58 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -22,7 +22,11 @@ struct blk_mq_tags { }; -extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node, int alloc_policy); +extern bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set); +extern struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *tag_set, + unsigned int nr_tags, + unsigned int reserved_tags, + int node, int alloc_policy); extern void blk_mq_free_tags(struct blk_mq_tags *tags); extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data); diff --git a/block/blk-mq.c b/block/blk-mq.c index f0c40fcbd8ae..db87b0f57dbe 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2075,13 +2075,14 @@ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, } } -void blk_mq_free_rq_map(struct blk_mq_tags *tags) +void blk_mq_free_rq_map(struct blk_mq_tags *tags, bool shared) { kfree(tags->rqs); tags->rqs = NULL; kfree(tags->static_rqs); tags->static_rqs = NULL; - blk_mq_free_tags(tags); + if (!shared) + blk_mq_free_tags(tags); } struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, @@ -2096,7 +2097,7 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, if (node == NUMA_NO_NODE) node = set->numa_node; - tags = blk_mq_init_tags(nr_tags, reserved_tags, node, + tags = blk_mq_init_tags(set, nr_tags, reserved_tags, node, BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); if (!tags) return NULL; @@ -2105,7 +2106,8 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node); if (!tags->rqs) { - blk_mq_free_tags(tags); + if (!blk_mq_is_sbitmap_shared(set)) + blk_mq_free_tags(tags); return NULL; } @@ -2114,7 +2116,8 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, node); if (!tags->static_rqs) { kfree(tags->rqs); - blk_mq_free_tags(tags); + if (!blk_mq_is_sbitmap_shared(set)) + blk_mq_free_tags(tags); return NULL; } @@ -2446,7 +2449,7 @@ static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx) if (!ret) return true; - blk_mq_free_rq_map(set->tags[hctx_idx]); + blk_mq_free_rq_map(set->tags[hctx_idx], blk_mq_is_sbitmap_shared(set)); set->tags[hctx_idx] = NULL; return false; } @@ -2456,7 +2459,8 @@ static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set, { if (set->tags && set->tags[hctx_idx]) { blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx); - blk_mq_free_rq_map(set->tags[hctx_idx]); + blk_mq_free_rq_map(set->tags[hctx_idx], + blk_mq_is_sbitmap_shared(set)); set->tags[hctx_idx] = NULL; } } @@ -2954,7 +2958,7 @@ static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set) out_unwind: while (--i >= 0) - blk_mq_free_rq_map(set->tags[i]); + blk_mq_free_rq_map(set->tags[i], blk_mq_is_sbitmap_shared(set)); return -ENOMEM; } @@ -3099,6 +3103,20 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set) if (ret) goto out_free_mq_map; + if (blk_mq_is_sbitmap_shared(set)) { + if (!blk_mq_init_shared_sbitmap(set)) { + ret = -ENOMEM; + goto out_free_mq_map; + } + + for (i = 0; i < set->nr_hw_queues; i++) { + struct blk_mq_tags *tags = set->tags[i]; + + tags->bitmap_tags = &set->shared_bitmap_tags; + tags->breserved_tags = &set->shared_breserved_tags; + } + } + mutex_init(&set->tag_list_lock); INIT_LIST_HEAD(&set->tag_list); @@ -3168,8 +3186,17 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) q->elevator->type->ops.depth_updated(hctx); } - if (!ret) + if (!ret) { + if (blk_mq_is_sbitmap_shared(set)) { + sbitmap_queue_resize(&set->shared_bitmap_tags, nr); + sbitmap_queue_resize(&set->shared_breserved_tags, nr); + } q->nr_requests = nr; + } + /* + * if ret != 0, q->nr_requests would not be updated, yet the depth + * for some hctx may have changed - is that right? + */ blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); diff --git a/block/blk-mq.h b/block/blk-mq.h index 78d38b5f2793..c4b8213dfdfc 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -53,7 +53,7 @@ struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx, */ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, unsigned int hctx_idx); -void blk_mq_free_rq_map(struct blk_mq_tags *tags); +void blk_mq_free_rq_map(struct blk_mq_tags *tags, bool shared); struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, unsigned int hctx_idx, unsigned int nr_tags, @@ -166,6 +166,11 @@ struct blk_mq_alloc_data { struct blk_mq_hw_ctx *hctx; }; +static inline bool blk_mq_is_sbitmap_shared(struct blk_mq_tag_set *tag_set) +{ + return !!(tag_set->flags & BLK_MQ_F_TAG_HCTX_SHARED); +} + static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data) { if (data->flags & BLK_MQ_REQ_INTERNAL) diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 147185394a25..670e9a949d32 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -109,6 +109,12 @@ struct blk_mq_tag_set { unsigned int flags; /* BLK_MQ_F_* */ void *driver_data; + struct sbitmap_queue shared_bitmap_tags; + struct sbitmap_queue shared_breserved_tags; + + struct sbitmap_queue sched_shared_bitmap_tags; + struct sbitmap_queue sched_shared_breserved_tags; + struct blk_mq_tags **tags; struct mutex tag_list_lock; @@ -226,6 +232,7 @@ struct blk_mq_ops { enum { BLK_MQ_F_SHOULD_MERGE = 1 << 0, BLK_MQ_F_TAG_QUEUE_SHARED = 1 << 1, + BLK_MQ_F_TAG_HCTX_SHARED = 1 << 2, BLK_MQ_F_BLOCKING = 1 << 5, BLK_MQ_F_NO_SCHED = 1 << 6, BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,