From patchwork Tue Jun 8 23:07:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 12308383 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 0E88DC48BDF for ; Tue, 8 Jun 2021 23:07:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7C8961278 for ; Tue, 8 Jun 2021 23:07:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235308AbhFHXJg (ORCPT ); Tue, 8 Jun 2021 19:09:36 -0400 Received: from mail-pl1-f172.google.com ([209.85.214.172]:40827 "EHLO mail-pl1-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235225AbhFHXJg (ORCPT ); Tue, 8 Jun 2021 19:09:36 -0400 Received: by mail-pl1-f172.google.com with SMTP id e7so11519805plj.7 for ; Tue, 08 Jun 2021 16:07:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=DKj20C0bcnYEdi2no4p//QdL1zitAi+dZIPfHAogfi4=; b=HtXbnJEGzK+uG2rr4QWv7ZeNZ3/IXU2keJuEgT2A9gQdDZ2du9ztjhvA0XVgD9VUHL /RZnMuISqcNblVR3dvLhdYelNyMrVfAWXG7yw06nMwyVeADTywSm6lHrVWvFNqcRrEbN Y/CJjiiF8G+nRqaEPmHE3uiY2cFqkMgqMpF/yPefrX7dUA0SCqtv6YGzzmHkc0kHkKrD heT6j0yWHuPpjCZNBGynqj4I/Y+JJDbOwWfizeAoNKDtcu25/sMyTKKAXZ71jd1s3l54 3MKuXuFLzGvyEB/h+X2uUqKEUeMYOikexo6ow3INHPV1kUVEQM0ebz8GXXhE2DZxbg5x /+/A== X-Gm-Message-State: AOAM530OUzJYt4+mlZgtxA+wMIZHP6qf0phArVUFtEPR5r1t+C/kT24R imoZN/buktp1Fsgpv5NFdYU= X-Google-Smtp-Source: ABdhPJzAXkQGT2eBDgLCNWGRzUpLfOZhR0WuDVmyj3TAQEa4od/srKyR6+ufSc//U+yN+QEu4D/HXg== X-Received: by 2002:a17:90a:5b17:: with SMTP id o23mr28175525pji.14.1623193647698; Tue, 08 Jun 2021 16:07:27 -0700 (PDT) Received: from asus.hsd1.ca.comcast.net (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id s21sm11395838pfw.57.2021.06.08.16.07.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Jun 2021 16:07:27 -0700 (PDT) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Jaegeuk Kim , Bart Van Assche , Damien Le Moal , Hannes Reinecke , Ming Lei , Johannes Thumshirn , Himanshu Madhani Subject: [PATCH 11/14] block/mq-deadline: Reserve 25% of scheduler tags for synchronous requests Date: Tue, 8 Jun 2021 16:07:00 -0700 Message-Id: <20210608230703.19510-12-bvanassche@acm.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210608230703.19510-1-bvanassche@acm.org> References: <20210608230703.19510-1-bvanassche@acm.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org For interactive workloads it is important that synchronous requests are not delayed. Hence reserve 25% of scheduler tags for synchronous requests. This patch still allows asynchronous requests to fill the hardware queues since blk_mq_init_sched() makes sure that the number of scheduler requests is the double of the hardware queue depth. From blk_mq_init_sched(): q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth, BLKDEV_MAX_RQ); Cc: Damien Le Moal Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Ming Lei Cc: Johannes Thumshirn Cc: Himanshu Madhani Signed-off-by: Bart Van Assche --- block/mq-deadline.c | 52 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 1d1bb7a41d2a..a7d0584437d1 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -67,6 +67,7 @@ struct deadline_data { int fifo_batch; int writes_starved; int front_merges; + u32 async_depth; spinlock_t lock; spinlock_t zone_lock; @@ -397,6 +398,44 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) return rq; } +/* + * Called by __blk_mq_alloc_request(). The shallow_depth value set by this + * function is used by __blk_mq_get_tag(). + */ +static void dd_limit_depth(unsigned int op, struct blk_mq_alloc_data *data) +{ + struct deadline_data *dd = data->q->elevator->elevator_data; + + /* Do not throttle synchronous reads. */ + if (op_is_sync(op) && !op_is_write(op)) + return; + + /* + * Throttle asynchronous requests and writes such that these requests + * do not block the allocation of synchronous requests. + */ + data->shallow_depth = dd->async_depth; +} + +/* Called by blk_mq_update_nr_requests(). */ +static void dd_depth_updated(struct blk_mq_hw_ctx *hctx) +{ + struct request_queue *q = hctx->queue; + struct deadline_data *dd = q->elevator->elevator_data; + struct blk_mq_tags *tags = hctx->sched_tags; + + dd->async_depth = max(1UL, 3 * q->nr_requests / 4); + + sbitmap_queue_min_shallow_depth(tags->bitmap_tags, dd->async_depth); +} + +/* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */ +static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +{ + dd_depth_updated(hctx); + return 0; +} + static void dd_exit_sched(struct elevator_queue *e) { struct deadline_data *dd = e->elevator_data; @@ -733,6 +772,15 @@ static int deadline_starved_show(void *data, struct seq_file *m) return 0; } +static int dd_async_depth_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + + seq_printf(m, "%u\n", dd->async_depth); + return 0; +} + static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos) __acquires(&dd->lock) { @@ -775,6 +823,7 @@ static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = { DEADLINE_QUEUE_DDIR_ATTRS(write), {"batching", 0400, deadline_batching_show}, {"starved", 0400, deadline_starved_show}, + {"async_depth", 0400, dd_async_depth_show}, {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops}, {}, }; @@ -783,6 +832,8 @@ static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = { static struct elevator_type mq_deadline = { .ops = { + .depth_updated = dd_depth_updated, + .limit_depth = dd_limit_depth, .insert_requests = dd_insert_requests, .dispatch_request = dd_dispatch_request, .prepare_request = dd_prepare_request, @@ -796,6 +847,7 @@ static struct elevator_type mq_deadline = { .has_work = dd_has_work, .init_sched = dd_init_sched, .exit_sched = dd_exit_sched, + .init_hctx = dd_init_hctx, }, #ifdef CONFIG_BLK_DEBUG_FS