From patchwork Fri Dec 18 21:44:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 11983013 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 EF6B7C2D0E4 for ; Fri, 18 Dec 2020 21:45:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C87D623B7B for ; Fri, 18 Dec 2020 21:45:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726173AbgLRVpC (ORCPT ); Fri, 18 Dec 2020 16:45:02 -0500 Received: from mx2.suse.de ([195.135.220.15]:52726 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725901AbgLRVpC (ORCPT ); Fri, 18 Dec 2020 16:45:02 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 327C6AD18; Fri, 18 Dec 2020 21:44:20 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id B4C381E132A; Fri, 18 Dec 2020 22:44:19 +0100 (CET) From: Jan Kara To: Jens Axboe Cc: , hare@suse.de, Kashyap Desai , Jan Kara Subject: [PATCH 1/2] Revert "blk-mq, elevator: Count requests per hctx to improve performance" Date: Fri, 18 Dec 2020 22:44:11 +0100 Message-Id: <20201218214412.1543-2-jack@suse.cz> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20201218214412.1543-1-jack@suse.cz> References: <20201218214412.1543-1-jack@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This reverts commit b445547ec1bbd3e7bf4b1c142550942f70527d95. Since both mq-deadline and BFQ completely ignore hctx they are passed to their dispatch function and dispatch whatever request they deem fit checking whether any request for a particular hctx is queued is just pointless since we'll very likely get a request from a different hctx anyway. In the following commit we'll deal with lock contention in these IO schedulers in presence of multiple HW queues in a different way. Signed-off-by: Jan Kara --- block/bfq-iosched.c | 5 ----- block/blk-mq.c | 1 - block/mq-deadline.c | 6 ------ include/linux/blk-mq.h | 4 ---- 4 files changed, 16 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 9e81d1052091..a99dfaa75a8c 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4640,9 +4640,6 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) { struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; - if (!atomic_read(&hctx->elevator_queued)) - return false; - /* * Avoiding lock: a race on bfqd->busy_queues should cause at * most a call to dispatch for nothing @@ -5557,7 +5554,6 @@ static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, rq = list_first_entry(list, struct request, queuelist); list_del_init(&rq->queuelist); bfq_insert_request(hctx, rq, at_head); - atomic_inc(&hctx->elevator_queued); } } @@ -5925,7 +5921,6 @@ static void bfq_finish_requeue_request(struct request *rq) bfq_completed_request(bfqq, bfqd); bfq_finish_requeue_request_body(bfqq); - atomic_dec(&rq->mq_hctx->elevator_queued); spin_unlock_irqrestore(&bfqd->lock, flags); } else { diff --git a/block/blk-mq.c b/block/blk-mq.c index b09ce00cc6af..57d0461f2be5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2670,7 +2670,6 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set, goto free_hctx; atomic_set(&hctx->nr_active, 0); - atomic_set(&hctx->elevator_queued, 0); if (node == NUMA_NO_NODE) node = set->numa_node; hctx->numa_node = node; diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 800ac902809b..b57470e154c8 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -386,8 +386,6 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) spin_lock(&dd->lock); rq = __dd_dispatch_request(dd); spin_unlock(&dd->lock); - if (rq) - atomic_dec(&rq->mq_hctx->elevator_queued); return rq; } @@ -535,7 +533,6 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, rq = list_first_entry(list, struct request, queuelist); list_del_init(&rq->queuelist); dd_insert_request(hctx, rq, at_head); - atomic_inc(&hctx->elevator_queued); } spin_unlock(&dd->lock); } @@ -582,9 +579,6 @@ static bool dd_has_work(struct blk_mq_hw_ctx *hctx) { struct deadline_data *dd = hctx->queue->elevator->elevator_data; - if (!atomic_read(&hctx->elevator_queued)) - return false; - return !list_empty_careful(&dd->dispatch) || !list_empty_careful(&dd->fifo_list[0]) || !list_empty_careful(&dd->fifo_list[1]); diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 47b021952ac7..8296811a031e 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -140,10 +140,6 @@ struct blk_mq_hw_ctx { * shared across request queues. */ atomic_t nr_active; - /** - * @elevator_queued: Number of queued requests on hctx. - */ - atomic_t elevator_queued; /** @cpuhp_online: List to store request if CPU is going to die */ struct hlist_node cpuhp_online;