From patchwork Sat Oct 14 09:22:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 10006309 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C73116037E for ; Sat, 14 Oct 2017 09:23:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B01D8291C8 for ; Sat, 14 Oct 2017 09:23:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A313C291CA; Sat, 14 Oct 2017 09:23:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 16C72291C8 for ; Sat, 14 Oct 2017 09:23:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753602AbdJNJXU (ORCPT ); Sat, 14 Oct 2017 05:23:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51234 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751716AbdJNJXS (ORCPT ); Sat, 14 Oct 2017 05:23:18 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E0F8A81DE3; Sat, 14 Oct 2017 09:23:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E0F8A81DE3 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=ming.lei@redhat.com Received: from localhost (ovpn-12-19.pek2.redhat.com [10.72.12.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D41917AB1; Sat, 14 Oct 2017 09:23:15 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Cc: Bart Van Assche , Laurence Oberman , Paolo Valente , Oleksandr Natalenko , Tom Nguyen , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Omar Sandoval , John Garry , Ming Lei Subject: [PATCH V10 6/8] blk-mq-sched: improve dispatching from sw queue Date: Sat, 14 Oct 2017 17:22:30 +0800 Message-Id: <20171014092232.13943-7-ming.lei@redhat.com> In-Reply-To: <20171014092232.13943-1-ming.lei@redhat.com> References: <20171014092232.13943-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Sat, 14 Oct 2017 09:23:18 +0000 (UTC) Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP SCSI devices use host-wide tagset, and the shared driver tag space is often quite big. Meantime there is also queue depth for each lun( .cmd_per_lun), which is often small, for example, on both lpfc and qla2xxx, .cmd_per_lun is just 3. So lots of requests may stay in sw queue, and we always flush all belonging to same hw queue and dispatch them all to driver, unfortunately it is easy to cause queue busy because of the small .cmd_per_lun. Once these requests are flushed out, they have to stay in hctx->dispatch, and no bio merge can participate into these requests, and sequential IO performance is hurt a lot. This patch introduces blk_mq_dequeue_from_ctx for dequeuing request from sw queue so that we can dispatch them in scheduler's way, then we can avoid to dequeue too many requests from sw queue when ->dispatch isn't flushed completely. This patch improves dispatching from sw queue by using the callback of .get_budget and .put_budget Reviewed-by: Omar Sandoval Signed-off-by: Ming Lei --- block/blk-mq-sched.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++-- block/blk-mq.c | 39 ++++++++++++++++++++++++++ block/blk-mq.h | 2 ++ include/linux/blk-mq.h | 2 ++ 4 files changed, 114 insertions(+), 3 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 8e525e66a0d9..df8581bb0a37 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -128,6 +128,61 @@ static bool blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) return false; } +static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *ctx) +{ + unsigned idx = ctx->index_hw; + + if (++idx == hctx->nr_ctx) + idx = 0; + + return hctx->ctxs[idx]; +} + +/* return true if hctx need to run again */ +static bool blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) +{ + struct request_queue *q = hctx->queue; + LIST_HEAD(rq_list); + struct blk_mq_ctx *ctx = READ_ONCE(hctx->dispatch_from); + + do { + struct request *rq; + blk_status_t ret; + + if (!sbitmap_any_bit_set(&hctx->ctx_map)) + break; + + ret = blk_mq_get_dispatch_budget(hctx); + if (ret == BLK_STS_RESOURCE) + return true; + + rq = blk_mq_dequeue_from_ctx(hctx, ctx); + if (!rq) { + blk_mq_put_dispatch_budget(hctx); + break; + } else if (ret != BLK_STS_OK) { + blk_mq_end_request(rq, ret); + continue; + } + + /* + * Now this rq owns the budget which has to be released + * if this rq won't be queued to driver via .queue_rq() + * in blk_mq_dispatch_rq_list(). + */ + list_add(&rq->queuelist, &rq_list); + + /* round robin for fair dispatch */ + ctx = blk_mq_next_ctx(hctx, rq->mq_ctx); + + } while (blk_mq_dispatch_rq_list(q, &rq_list, true)); + + WRITE_ONCE(hctx->dispatch_from, ctx); + + return false; +} + /* return true if hw queue need to be run again */ bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) { @@ -169,11 +224,24 @@ bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) */ if (!list_empty(&rq_list)) { blk_mq_sched_mark_restart_hctx(hctx); - if (blk_mq_dispatch_rq_list(q, &rq_list, false) && - has_sched_dispatch) - run_queue = blk_mq_do_dispatch_sched(hctx); + if (blk_mq_dispatch_rq_list(q, &rq_list, false)) { + if (has_sched_dispatch) + run_queue = blk_mq_do_dispatch_sched(hctx); + else + run_queue = blk_mq_do_dispatch_ctx(hctx); + } } else if (has_sched_dispatch) { run_queue = blk_mq_do_dispatch_sched(hctx); + } else if (q->mq_ops->get_budget) { + /* + * If we need to get budget before queuing request, we + * dequeue request one by one from sw queue for avoiding + * to mess up I/O merge when dispatch runs out of resource. + * + * TODO: get more budgets, and dequeue more requests in + * one time. + */ + run_queue = blk_mq_do_dispatch_ctx(hctx); } else { blk_mq_flush_busy_ctxs(hctx, &rq_list); blk_mq_dispatch_rq_list(q, &rq_list, false); diff --git a/block/blk-mq.c b/block/blk-mq.c index dcb467369999..097ca3ece716 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -914,6 +914,45 @@ void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list) } EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs); +struct dispatch_rq_data { + struct blk_mq_hw_ctx *hctx; + struct request *rq; +}; + +static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr, + void *data) +{ + struct dispatch_rq_data *dispatch_data = data; + struct blk_mq_hw_ctx *hctx = dispatch_data->hctx; + struct blk_mq_ctx *ctx = hctx->ctxs[bitnr]; + + spin_lock(&ctx->lock); + if (unlikely(!list_empty(&ctx->rq_list))) { + dispatch_data->rq = list_entry_rq(ctx->rq_list.next); + list_del_init(&dispatch_data->rq->queuelist); + if (list_empty(&ctx->rq_list)) + sbitmap_clear_bit(sb, bitnr); + } + spin_unlock(&ctx->lock); + + return !dispatch_data->rq; +} + +struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *start) +{ + unsigned off = start ? start->index_hw : 0; + struct dispatch_rq_data data = { + .hctx = hctx, + .rq = NULL, + }; + + __sbitmap_for_each_set(&hctx->ctx_map, off, + dispatch_rq_from_ctx, &data); + + return data.rq; +} + static inline unsigned int queued_to_index(unsigned int queued) { if (!queued) diff --git a/block/blk-mq.h b/block/blk-mq.h index e413b732374e..522b420dedc0 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -35,6 +35,8 @@ void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list); bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx); bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx, bool wait); +struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *start); /* * Internal helpers for allocating/freeing the request map diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 901457df3d64..e5e6becd57d3 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -30,6 +30,8 @@ struct blk_mq_hw_ctx { struct sbitmap ctx_map; + struct blk_mq_ctx *dispatch_from; + struct blk_mq_ctx **ctxs; unsigned int nr_ctx;