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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 E1B1CC433DF for ; Fri, 15 May 2020 15:45:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4D7F2076A for ; Fri, 15 May 2020 15:45:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726234AbgEOPpJ (ORCPT ); Fri, 15 May 2020 11:45:09 -0400 Received: from verein.lst.de ([213.95.11.211]:57396 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726188AbgEOPpJ (ORCPT ); Fri, 15 May 2020 11:45:09 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 0E35168C65; Fri, 15 May 2020 17:45:04 +0200 (CEST) Date: Fri, 15 May 2020 17:45:03 +0200 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, John Garry , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner Subject: Re: [PATCH 0/6] blk-mq: improvement CPU hotplug(simplified version) Message-ID: <20200515154503.GA30414@lst.de> References: <20200515014153.2403464-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200515014153.2403464-1-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org FYI, I think this could be significantly simplified by stashing the input bio and output rq into struct blk_mq_alloc_data instead of creating another structure. Something like this untested patch on top of the whole series shows where I'd like to get to: diff --git a/block/blk-mq.c b/block/blk-mq.c index bcc894faf4e36..52b8917ea7cb6 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -41,10 +41,6 @@ #include "blk-mq-sched.h" #include "blk-rq-qos.h" -static struct request *__blk_mq_get_request(struct request_queue *q, - struct bio *bio, - struct blk_mq_alloc_data *data); - static void blk_mq_poll_stats_start(struct request_queue *q); static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb); @@ -274,8 +270,8 @@ static inline bool blk_mq_need_time_stamp(struct request *rq) return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS)) || rq->q->elevator; } -static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, - unsigned int tag, unsigned int op, u64 alloc_time_ns) +static void blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, unsigned int tag, + unsigned int op, u64 alloc_time_ns) { struct blk_mq_tags *tags = blk_mq_tags_from_data(data); struct request *rq = tags->static_rqs[tag]; @@ -333,29 +329,13 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, data->ctx->rq_dispatched[op_is_sync(op)]++; refcount_set(&rq->ref, 1); - return rq; -} - -struct blk_mq_smp_call_info { - struct request_queue *q; - struct blk_mq_alloc_data *data; - struct request *rq; - struct bio *bio; -}; - -static void __blk_mq_alloc_request(void *alloc_info) -{ - struct blk_mq_smp_call_info *info = alloc_info; - - info->rq = __blk_mq_get_request(info->q, info->bio, info->data); + data->rq = rq; } -static struct request *__blk_mq_get_request(struct request_queue *q, - struct bio *bio, - struct blk_mq_alloc_data *data) +static void __blk_mq_get_request(struct blk_mq_alloc_data *data) { + struct request_queue *q = data->q; struct elevator_queue *e = q->elevator; - struct request *rq; unsigned int tag; u64 alloc_time_ns = 0; @@ -365,8 +345,6 @@ static struct request *__blk_mq_get_request(struct request_queue *q, if (blk_queue_rq_alloc_time(q)) alloc_time_ns = ktime_get_ns(); - data->q = q; - WARN_ON_ONCE(data->ctx || data->hctx); preempt_disable(); @@ -398,64 +376,61 @@ static struct request *__blk_mq_get_request(struct request_queue *q, data->ctx = NULL; data->hctx = NULL; blk_queue_exit(q); - return NULL; + return; } - rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags, alloc_time_ns); + blk_mq_rq_ctx_init(data, tag, data->cmd_flags, alloc_time_ns); if (!op_is_flush(data->cmd_flags)) { - rq->elv.icq = NULL; + data->rq->elv.icq = NULL; if (e && e->type->ops.prepare_request) { if (e->type->icq_cache) - blk_mq_sched_assign_ioc(rq); + blk_mq_sched_assign_ioc(data->rq); - e->type->ops.prepare_request(rq, bio); - rq->rq_flags |= RQF_ELVPRIV; + e->type->ops.prepare_request(data->rq, data->bio); + data->rq->rq_flags |= RQF_ELVPRIV; } } data->hctx->queued++; - return rq; } -static struct request *blk_mq_get_request(struct request_queue *q, - struct bio *bio, - struct blk_mq_alloc_data *data) +static void blk_mq_get_request_cb(void *data) { - int ret; - struct blk_mq_smp_call_info info; - struct request *rq = __blk_mq_get_request(q, bio, data); - - if (rq) - return rq; + __blk_mq_get_request(data); +} - if (data->flags & BLK_MQ_REQ_NOWAIT) - return NULL; +static int blk_mq_get_request_cpumask(struct blk_mq_alloc_data *data, + const cpumask_t *mask) +{ + return smp_call_function_any(mask, blk_mq_get_request_cb, data, 1); +} +static struct request *blk_mq_get_request(struct blk_mq_alloc_data *data) +{ /* - * The allocation fails because of inactive hctx, so retry from - * online cpus. + * For !BLK_MQ_REQ_NOWAIT the allocation only fails due to an inactive + * hctx, so retry from an online CPU. */ - info.q = q; - info.bio = bio; - info.data = data; - - ret = smp_call_function_any(cpu_online_mask, __blk_mq_alloc_request, &info, 1); - if (ret) - return ERR_PTR(ret); - return info.rq; + __blk_mq_get_request(data); + if (!data->rq && !(data->flags & BLK_MQ_REQ_NOWAIT)) + blk_mq_get_request_cpumask(data, cpu_online_mask); + return data->rq; } struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, blk_mq_req_flags_t flags) { - struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op }; + struct blk_mq_alloc_data alloc_data = { + .q = q, + .flags = flags, + .cmd_flags = op, + }; struct request *rq; int ret; ret = blk_queue_enter(q, flags); if (ret) return ERR_PTR(ret); - - rq = blk_mq_get_request(q, NULL, &alloc_data); + rq = blk_mq_get_request(&alloc_data); blk_queue_exit(q); if (!rq) @@ -469,10 +444,14 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, EXPORT_SYMBOL(blk_mq_alloc_request); struct request *blk_mq_alloc_request_hctx(struct request_queue *q, - unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx) + unsigned int op, blk_mq_req_flags_t flags, + unsigned int hctx_idx) { - struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op }; - struct blk_mq_smp_call_info info = {.q = q, .data = &alloc_data}; + struct blk_mq_alloc_data alloc_data = { + .q = q, + .flags = flags, + .cmd_flags = op, + }; int ret; /* @@ -500,17 +479,9 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, return ERR_PTR(-EXDEV); } - ret = smp_call_function_any(alloc_data.hctx->cpumask, - __blk_mq_alloc_request, &info, 1); + blk_mq_get_request_cpumask(&alloc_data, alloc_data.hctx->cpumask); blk_queue_exit(q); - - if (ret) - return ERR_PTR(ret); - - if (!info.rq) - return ERR_PTR(-EWOULDBLOCK); - - return info.rq; + return alloc_data.rq; } EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx); @@ -2065,7 +2036,9 @@ blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) { const int is_sync = op_is_sync(bio->bi_opf); const int is_flush_fua = op_is_flush(bio->bi_opf); - struct blk_mq_alloc_data data = { .flags = 0}; + struct blk_mq_alloc_data data = { + .q = q, + }; struct request *rq; struct blk_plug *plug; struct request *same_queue_rq = NULL; @@ -2088,8 +2061,9 @@ blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) rq_qos_throttle(q, bio); + data.bio = bio; data.cmd_flags = bio->bi_opf; - rq = blk_mq_get_request(q, bio, &data); + rq = blk_mq_get_request(&data); if (unlikely(!rq)) { rq_qos_cleanup(q, bio); if (bio->bi_opf & REQ_NOWAIT) diff --git a/block/blk-mq.h b/block/blk-mq.h index 5ebc8d8d5a540..e07be009831e9 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -149,6 +149,7 @@ static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q) struct blk_mq_alloc_data { /* input parameter */ struct request_queue *q; + struct bio *bio; blk_mq_req_flags_t flags; unsigned int shallow_depth; unsigned int cmd_flags; @@ -157,6 +158,9 @@ struct blk_mq_alloc_data { /* input & output parameter */ struct blk_mq_ctx *ctx; struct blk_mq_hw_ctx *hctx; + + /* output parameter for __blk_mq_get_request */ + struct request *rq; }; static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)