From patchwork Sat Sep 30 10:27:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9979361 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 62D7860327 for ; Sat, 30 Sep 2017 10:28:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5315628F31 for ; Sat, 30 Sep 2017 10:28:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 47E67295BE; Sat, 30 Sep 2017 10:28:57 +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 C87FF28F31 for ; Sat, 30 Sep 2017 10:28:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752856AbdI3K2m (ORCPT ); Sat, 30 Sep 2017 06:28:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40470 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751160AbdI3K2i (ORCPT ); Sat, 30 Sep 2017 06:28:38 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id CC7584ACC7; Sat, 30 Sep 2017 10:28:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com CC7584ACC7 Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=ming.lei@redhat.com Received: from localhost (ovpn-12-31.pek2.redhat.com [10.72.12.31]) by smtp.corp.redhat.com (Postfix) with ESMTP id AFF8118621; Sat, 30 Sep 2017 10:28:25 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , Mike Snitzer , dm-devel@redhat.com Cc: Bart Van Assche , Laurence Oberman , Paolo Valente , Oleksandr Natalenko , Tom Nguyen , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Omar Sandoval , Ming Lei Subject: [PATCH V5 4/7] blk-mq: introduce blk_mq_dequeue_from_ctx() Date: Sat, 30 Sep 2017 18:27:17 +0800 Message-Id: <20170930102720.30219-5-ming.lei@redhat.com> In-Reply-To: <20170930102720.30219-1-ming.lei@redhat.com> References: <20170930102720.30219-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Sat, 30 Sep 2017 10:28:38 +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 This function is introduced for dequeuing request from sw queue so that we can dispatch it in scheduler's way. More importantly, some SCSI devices may set q->queue_depth, which is a per-request_queue limit, and applied on pending I/O from all hctxs. This function is introduced for avoiding to dequeue too many requests from sw queue when ->dispatch isn't flushed completely. Tested-by: Oleksandr Natalenko Tested-by: Tom Nguyen Tested-by: Paolo Valente Reviewed-by: Bart Van Assche Signed-off-by: Ming Lei --- block/blk-mq.c | 38 ++++++++++++++++++++++++++++++++++++++ block/blk-mq.h | 2 ++ 2 files changed, 40 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index d1b9fb539eba..8b49af1ade7f 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -882,6 +882,44 @@ 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 61aecf398a4b..915de58572e7 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