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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 5B741C43461 for ; Fri, 16 Apr 2021 08:42:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FD4D611AB for ; Fri, 16 Apr 2021 08:42:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238823AbhDPIm5 (ORCPT ); Fri, 16 Apr 2021 04:42:57 -0400 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:54259 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234914AbhDPIm5 (ORCPT ); Fri, 16 Apr 2021 04:42:57 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UVjmePT_1618562550; Received: from admindeMacBook-Pro-2.local(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UVjmePT_1618562550) by smtp.aliyun-inc.com(127.0.0.1); Fri, 16 Apr 2021 16:42:31 +0800 Subject: Re: [PATCH] block: introduce QUEUE_FLAG_POLL_CAP flag From: JeffleXu To: ming.lei@redhat.com, snitzer@redhat.com, axboe@kernel.dk Cc: linux-block@vger.kernel.org, dm-devel@redhat.com References: <20210401021927.343727-12-ming.lei@redhat.com> <20210416080037.26335-1-jefflexu@linux.alibaba.com> Message-ID: Date: Fri, 16 Apr 2021 16:42:30 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210416080037.26335-1-jefflexu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 4/16/21 4:00 PM, Jeffle Xu wrote: > Hi, > How about this patch to remove the extra poll_capable() method? > > And the following 'dm: support IO polling for bio-based dm device' needs > following change. > > ``` > + /* > + * Check for request-based device is remained to > + * dm_mq_init_request_queue()->blk_mq_init_allocated_queue(). > + * For bio-based device, only set QUEUE_FLAG_POLL when all underlying > + * devices supporting polling. > + */ > + if (__table_type_bio_based(t->type)) { > + if (dm_table_supports_poll(t)) { > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > + blk_queue_flag_set(QUEUE_FLAG_POLL, q); > + } > + else { > + blk_queue_flag_clear(QUEUE_FLAG_POLL, q); > + blk_queue_flag_clear(QUEUE_FLAG_POLL_CAP, q); > + } > + } > ``` > > > Introduce QUEUE_FLAG_POLL_CAP flag, indicating if the device supports IO > polling or not. Thus both blk-mq and bio-based device could set this > flag at the initialization phase, and then only this flag needs to be > checked instead of rechecking if the device has the ability of IO > polling when enabling IO polling via sysfs. > > For NVMe, the ability of IO polling may change after RESET, since > nvme.poll_queues module parameter may change. Thus the ability of IO > polling need to be rechecked after RESET. > The defect of this approach is that all device drivers that may change tag_set after initialization (e.g., NVMe RESET) need to update QUEUE_FLAG_POLL_CAP. Previous this patch, tag_set is checked directly in queue_poll_store, and thus device drivers don't need to care the queue_flags. > Signed-off-by: Jeffle Xu > --- > block/blk-mq.c | 5 +++-- > block/blk-sysfs.c | 3 +-- > drivers/nvme/host/core.c | 2 ++ > include/linux/blk-mq.h | 12 ++++++++++++ > include/linux/blkdev.h | 2 ++ > 5 files changed, 20 insertions(+), 4 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 414f5d99d9de..55ef6b975169 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -3227,9 +3227,10 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, > q->tag_set = set; > > q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT; > - if (set->nr_maps > HCTX_TYPE_POLL && > - set->map[HCTX_TYPE_POLL].nr_queues) > + if (blk_mq_poll_capable(set)) { > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > blk_queue_flag_set(QUEUE_FLAG_POLL, q); > + } > > q->sg_reserved_size = INT_MAX; > > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index db3268d41274..64f0ab84b606 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -426,8 +426,7 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page, > unsigned long poll_on; > ssize_t ret; > > - if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL || > - !q->tag_set->map[HCTX_TYPE_POLL].nr_queues) > + if(!blk_queue_poll_cap(q)) > return -EINVAL; > > ret = queue_var_store(&poll_on, page, count); > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index bb7da34dd967..5344cc877b05 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -2210,6 +2210,8 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id) > ns->lba_shift = id->lbaf[lbaf].ds; > nvme_set_queue_limits(ns->ctrl, ns->queue); > > + blk_mq_check_poll(ns->disk->queue, ns->disk->queue->tag_set); > + > ret = nvme_configure_metadata(ns, id); > if (ret) > goto out_unfreeze; > diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h > index 2c473c9b8990..ee4c89c8bebc 100644 > --- a/include/linux/blk-mq.h > +++ b/include/linux/blk-mq.h > @@ -618,4 +618,16 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio); > void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, > struct lock_class_key *key); > > +static inline bool blk_mq_poll_capable(struct blk_mq_tag_set *set) > +{ > + return set->nr_maps > HCTX_TYPE_POLL && > + set->map[HCTX_TYPE_POLL].nr_queues; > +} > + > +static inline void blk_mq_check_poll(struct request_queue *q, > + struct blk_mq_tag_set *set) > +{ > + if (blk_mq_poll_capable(set)) > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > +} Sorry it should be > +static inline void blk_mq_check_poll(struct request_queue *q, > + struct blk_mq_tag_set *set) > +{ > + if (blk_mq_poll_capable(set)) > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > +} > + else > + blk_queue_flag_clear(QUEUE_FLAG_POLL_CAP, q); > +} > #endif > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index 1e88116dc070..d192a106bf40 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -621,6 +621,7 @@ struct request_queue { > #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */ > #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */ > #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */ > +#define QUEUE_FLAG_POLL_CAP 30 /* device supports IO polling */ > > #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ > (1 << QUEUE_FLAG_SAME_COMP) | \ > @@ -668,6 +669,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); > #define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags) > #define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags) > #define blk_queue_poll(q) test_bit(QUEUE_FLAG_POLL, &(q)->queue_flags) > +#define blk_queue_poll_cap(q) test_bit(QUEUE_FLAG_POLL_CAP, &(q)->queue_flags) > > extern void blk_set_pm_only(struct request_queue *q); > extern void blk_clear_pm_only(struct request_queue *q); > -- Thanks, Jeffle