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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 711CAC2D0F9 for ; Wed, 13 May 2020 09:55:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F08D2492C for ; Wed, 13 May 2020 09:55:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZokLtJQP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732931AbgEMJzi (ORCPT ); Wed, 13 May 2020 05:55:38 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:20494 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388285AbgEMJzh (ORCPT ); Wed, 13 May 2020 05:55:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589363735; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QQzkclllBs4XUNDegahETlcrIEqyRzbIznR5XK6bm7s=; b=ZokLtJQPedKxkycw86BCOaiu/BGIJQW4lm8ZEa+NVSjWAvtasWjDGbtOHu+yK5/CDIzwzk 1o61RzYf8/M4GYuONST0WOfzG0LNht0ecfNKNpW811/qOuPfNWuIjtPk6v146cuypx2a86 7rw8FA4nNWjoLk20Jo1agIBC8DC5/Ew= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-225-u4EjNF2lPlWomqMzRNDwXg-1; Wed, 13 May 2020 05:55:30 -0400 X-MC-Unique: u4EjNF2lPlWomqMzRNDwXg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 70E3A107ACCD; Wed, 13 May 2020 09:55:29 +0000 (UTC) Received: from localhost (ovpn-12-166.pek2.redhat.com [10.72.12.166]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9448762925; Wed, 13 May 2020 09:55:28 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Sagi Grimberg , Baolin Wang , Christoph Hellwig Subject: [PATCH 6/9] blk-mq: move code for handling partial dispatch into one helper Date: Wed, 13 May 2020 17:54:40 +0800 Message-Id: <20200513095443.2038859-7-ming.lei@redhat.com> In-Reply-To: <20200513095443.2038859-1-ming.lei@redhat.com> References: <20200513095443.2038859-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Move code for handling partial dispatch into one helper, so that blk_mq_dispatch_rq_list gets a bit simpified, and easier to read. No functional change. Cc: Sagi Grimberg Cc: Baolin Wang Cc: Christoph Hellwig Signed-off-by: Ming Lei --- block/blk-mq.c | 126 ++++++++++++++++++++++++++----------------------- 1 file changed, 66 insertions(+), 60 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 34fd09adb7fc..86beb8c66868 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1231,6 +1231,71 @@ static blk_status_t blk_mq_dispatch_rq(struct request *rq, bool is_last) return rq->q->mq_ops->queue_rq(rq->mq_hctx, &bd); } +static void blk_mq_handle_partial_dispatch(struct blk_mq_hw_ctx *hctx, + struct list_head *list, enum prep_dispatch prep, + blk_status_t ret, bool queued) +{ + struct request_queue *q = hctx->queue; + bool needs_restart; + bool no_tag = false; + bool no_budget_avail = false; + + /* + * For non-shared tags, the RESTART check + * will suffice. + */ + if (prep == PREP_DISPATCH_NO_TAG && + (hctx->flags & BLK_MQ_F_TAG_SHARED)) + no_tag = true; + if (prep == PREP_DISPATCH_NO_BUDGET) + no_budget_avail = true; + + /* + * If we didn't flush the entire list, we could have told + * the driver there was more coming, but that turned out to + * be a lie. + */ + if (q->mq_ops->commit_rqs && queued) + q->mq_ops->commit_rqs(hctx); + + spin_lock(&hctx->lock); + list_splice_tail_init(list, &hctx->dispatch); + spin_unlock(&hctx->lock); + + /* + * If SCHED_RESTART was set by the caller of this function and + * it is no longer set that means that it was cleared by another + * thread and hence that a queue rerun is needed. + * + * If 'no_tag' is set, that means that we failed getting + * a driver tag with an I/O scheduler attached. If our dispatch + * waitqueue is no longer active, ensure that we run the queue + * AFTER adding our entries back to the list. + * + * If no I/O scheduler has been configured it is possible that + * the hardware queue got stopped and restarted before requests + * were pushed back onto the dispatch list. Rerun the queue to + * avoid starvation. Notes: + * - blk_mq_run_hw_queue() checks whether or not a queue has + * been stopped before rerunning a queue. + * - Some but not all block drivers stop a queue before + * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq + * and dm-rq. + * + * If driver returns BLK_STS_RESOURCE and SCHED_RESTART + * bit is set, run queue after a delay to avoid IO stalls + * that could otherwise occur if the queue is idle. We'll do + * similar if we couldn't get budget and SCHED_RESTART is set. + */ + needs_restart = blk_mq_sched_needs_restart(hctx); + if (!needs_restart || + (no_tag && list_empty_careful(&hctx->dispatch_wait.entry))) + blk_mq_run_hw_queue(hctx, true); + else if (needs_restart && (ret == BLK_STS_RESOURCE || + no_budget_avail)) + blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY); +} + /* * Returns true if we did some work AND can potentially do more. */ @@ -1238,7 +1303,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, bool got_budget) { enum prep_dispatch prep; - struct request_queue *q = hctx->queue; struct request *rq; int errors, queued; blk_status_t ret = BLK_STS_OK; @@ -1296,65 +1360,7 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, * that is where we will continue on next queue run. */ if (!list_empty(list)) { - bool needs_restart; - bool no_tag = false; - bool no_budget_avail = false; - - /* - * For non-shared tags, the RESTART check - * will suffice. - */ - if (prep == PREP_DISPATCH_NO_TAG && - (hctx->flags & BLK_MQ_F_TAG_SHARED)) - no_tag = true; - if (prep == PREP_DISPATCH_NO_BUDGET) - no_budget_avail = true; - - /* - * If we didn't flush the entire list, we could have told - * the driver there was more coming, but that turned out to - * be a lie. - */ - if (q->mq_ops->commit_rqs && queued) - q->mq_ops->commit_rqs(hctx); - - spin_lock(&hctx->lock); - list_splice_tail_init(list, &hctx->dispatch); - spin_unlock(&hctx->lock); - - /* - * If SCHED_RESTART was set by the caller of this function and - * it is no longer set that means that it was cleared by another - * thread and hence that a queue rerun is needed. - * - * If 'no_tag' is set, that means that we failed getting - * a driver tag with an I/O scheduler attached. If our dispatch - * waitqueue is no longer active, ensure that we run the queue - * AFTER adding our entries back to the list. - * - * If no I/O scheduler has been configured it is possible that - * the hardware queue got stopped and restarted before requests - * were pushed back onto the dispatch list. Rerun the queue to - * avoid starvation. Notes: - * - blk_mq_run_hw_queue() checks whether or not a queue has - * been stopped before rerunning a queue. - * - Some but not all block drivers stop a queue before - * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq - * and dm-rq. - * - * If driver returns BLK_STS_RESOURCE and SCHED_RESTART - * bit is set, run queue after a delay to avoid IO stalls - * that could otherwise occur if the queue is idle. We'll do - * similar if we couldn't get budget and SCHED_RESTART is set. - */ - needs_restart = blk_mq_sched_needs_restart(hctx); - if (!needs_restart || - (no_tag && list_empty_careful(&hctx->dispatch_wait.entry))) - blk_mq_run_hw_queue(hctx, true); - else if (needs_restart && (ret == BLK_STS_RESOURCE || - no_budget_avail)) - blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY); - + blk_mq_handle_partial_dispatch(hctx, list, prep, ret, !!queued); blk_mq_update_dispatch_busy(hctx, true); return false; } else -- 2.25.2