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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 752CEC3DA6E for ; Fri, 23 Dec 2022 05:53:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230042AbiLWFxQ (ORCPT ); Fri, 23 Dec 2022 00:53:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229627AbiLWFxO (ORCPT ); Fri, 23 Dec 2022 00:53:14 -0500 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D96BFCC3; Thu, 22 Dec 2022 21:53:13 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id 4134F6732D; Fri, 23 Dec 2022 06:53:09 +0100 (CET) Date: Fri, 23 Dec 2022 06:53:08 +0100 From: Christoph Hellwig To: Kemeng Shi Cc: axboe@kernel.dk, dwagner@suse.de, hare@suse.de, ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, john.garry@huawei.com Subject: Re: [PATCH 12/13] blk-mq: use switch/case to improve readability in blk_mq_try_issue_list_directly Message-ID: <20221223055308.GB2676@lst.de> References: <20221223125223.1687670-1-shikemeng@huaweicloud.com> <20221223125223.1687670-13-shikemeng@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221223125223.1687670-13-shikemeng@huaweicloud.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 23, 2022 at 08:52:22PM +0800, Kemeng Shi wrote: > + blk_mq_request_bypass_insert(rq, false, list_empty(list)); Please try to avoid the overly long line here. That beng said blk_mq_request_bypass_insert is simply a horrible API. I think we should do something like this: diff --git a/block/blk-flush.c b/block/blk-flush.c index 53202eff545efb..b6157ae11df651 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -432,7 +432,8 @@ void blk_insert_flush(struct request *rq) */ if ((policy & REQ_FSEQ_DATA) && !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { - blk_mq_request_bypass_insert(rq, false, true); + blk_mq_request_bypass_insert(rq); + blk_mq_run_hw_queue(rq->mq_hctx, false); return; } diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 23d1a90fec4271..d49fe4503b09d7 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -437,12 +437,13 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head, * Simply queue flush rq to the front of hctx->dispatch so that * intensive flush workloads can benefit in case of NCQ HW. */ - at_head = (rq->rq_flags & RQF_FLUSH_SEQ) ? true : at_head; - blk_mq_request_bypass_insert(rq, at_head, false); - goto run; - } - - if (e) { + spin_lock(&hctx->lock); + if ((rq->rq_flags & RQF_FLUSH_SEQ) || at_head) + list_add(&rq->queuelist, &hctx->dispatch); + else + list_add_tail(&rq->queuelist, &hctx->dispatch); + spin_unlock(&hctx->lock); + } else if (e) { LIST_HEAD(list); list_add(&rq->queuelist, &list); @@ -453,7 +454,6 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head, spin_unlock(&ctx->lock); } -run: if (run_queue) blk_mq_run_hw_queue(hctx, async); } diff --git a/block/blk-mq.c b/block/blk-mq.c index c5cf0dbca1db8d..43bb9b36c90da7 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1467,7 +1467,7 @@ static void blk_mq_requeue_work(struct work_struct *work) * merge. */ if (rq->rq_flags & RQF_DONTPREP) - blk_mq_request_bypass_insert(rq, false, false); + blk_mq_request_bypass_insert(rq); else blk_mq_sched_insert_request(rq, true, false, false); } @@ -2504,26 +2504,17 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, /** * blk_mq_request_bypass_insert - Insert a request at dispatch list. * @rq: Pointer to request to be inserted. - * @at_head: true if the request should be inserted at the head of the list. - * @run_queue: If we should run the hardware queue after inserting the request. * * Should only be used carefully, when the caller knows we want to * bypass a potential IO scheduler on the target device. */ -void blk_mq_request_bypass_insert(struct request *rq, bool at_head, - bool run_queue) +void blk_mq_request_bypass_insert(struct request *rq) { struct blk_mq_hw_ctx *hctx = rq->mq_hctx; spin_lock(&hctx->lock); - if (at_head) - list_add(&rq->queuelist, &hctx->dispatch); - else - list_add_tail(&rq->queuelist, &hctx->dispatch); + list_add_tail(&rq->queuelist, &hctx->dispatch); spin_unlock(&hctx->lock); - - if (run_queue) - blk_mq_run_hw_queue(hctx, false); } void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx, @@ -2670,10 +2661,17 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, blk_status_t ret = __blk_mq_try_issue_directly(hctx, rq, false, true); - if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) - blk_mq_request_bypass_insert(rq, false, true); - else if (ret != BLK_STS_OK) + switch (ret) { + case BLK_STS_OK: + break; + case BLK_STS_RESOURCE: + case BLK_STS_DEV_RESOURCE: + blk_mq_request_bypass_insert(rq); + blk_mq_run_hw_queue(rq->mq_hctx, false); + break; + default: blk_mq_end_request(rq, ret); + } } static blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last) @@ -2705,7 +2703,8 @@ static void blk_mq_plug_issue_direct(struct blk_plug *plug, bool from_schedule) break; case BLK_STS_RESOURCE: case BLK_STS_DEV_RESOURCE: - blk_mq_request_bypass_insert(rq, false, true); + blk_mq_request_bypass_insert(rq); + blk_mq_run_hw_queue(rq->mq_hctx, false); blk_mq_commit_rqs(hctx, &queued, from_schedule); return; default: @@ -2818,8 +2817,9 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, errors++; if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) { - blk_mq_request_bypass_insert(rq, false, - list_empty(list)); + blk_mq_request_bypass_insert(rq); + if (list_empty(list)) + blk_mq_run_hw_queue(rq->mq_hctx, false); break; } blk_mq_end_request(rq, ret); diff --git a/block/blk-mq.h b/block/blk-mq.h index ef59fee62780d3..3733429561e1eb 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -61,8 +61,7 @@ void blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set, */ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, bool at_head); -void blk_mq_request_bypass_insert(struct request *rq, bool at_head, - bool run_queue); +void blk_mq_request_bypass_insert(struct request *rq); void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx, struct list_head *list); void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,