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=-10.1 required=3.0 tests=BAYES_00,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 autolearn=unavailable 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 D7005C433DF for ; Tue, 28 Jul 2020 01:40:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACB142083E for ; Tue, 28 Jul 2020 01:40:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="A5GJW9YO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726320AbgG1Bkz (ORCPT ); Mon, 27 Jul 2020 21:40:55 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:26743 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726265AbgG1Bkz (ORCPT ); Mon, 27 Jul 2020 21:40:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595900453; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RCjKpXJyN62/c5yVHzk8RTcp4fhzn/0rYLcwRzNEGIA=; b=A5GJW9YOE8uXZnMoN3yVIr29h6EBm1iJiaPMjdRqwSDUIy8ZR4YODVsSXpez+C8/PPisaF WvIscXrl5kEuyRp601n/8ZGWgKtWma8lYmRl1zjV8pR7HVUTAMTVGeBAzycmBBhRPkpIr0 UqryNKBRlrsA4EmLL6iuxRcAR1Ed27c= 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-93-IQ4Zp378Nv6c-sGQCI9_0w-1; Mon, 27 Jul 2020 21:40:51 -0400 X-MC-Unique: IQ4Zp378Nv6c-sGQCI9_0w-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 311DC80183C; Tue, 28 Jul 2020 01:40:50 +0000 (UTC) Received: from T590 (ovpn-12-109.pek2.redhat.com [10.72.12.109]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9D1CF69323; Tue, 28 Jul 2020 01:40:42 +0000 (UTC) Date: Tue, 28 Jul 2020 09:40:38 +0800 From: Ming Lei To: Sagi Grimberg Cc: linux-nvme@lists.infradead.org, Christoph Hellwig , Keith Busch , Jens Axboe , linux-block@vger.kernel.org, Ming Lin , Chao Leng Subject: Re: [PATCH v5 1/2] blk-mq: add tagset quiesce interface Message-ID: <20200728014038.GA1305646@T590> References: <20200727231022.307602-1-sagi@grimberg.me> <20200727231022.307602-2-sagi@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200727231022.307602-2-sagi@grimberg.me> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Jul 27, 2020 at 04:10:21PM -0700, Sagi Grimberg wrote: > drivers that have shared tagsets may need to quiesce potentially a lot > of request queues that all share a single tagset (e.g. nvme). Add an interface > to quiesce all the queues on a given tagset. This interface is useful because > it can speedup the quiesce by doing it in parallel. > > For tagsets that have BLK_MQ_F_BLOCKING set, we use call_srcu to all hctxs > in parallel such that all of them wait for the same rcu elapsed period with > a per-hctx heap allocated rcu_synchronize. for tagsets that don't have > BLK_MQ_F_BLOCKING set, we simply call a single synchronize_rcu as this is > sufficient. > > Signed-off-by: Sagi Grimberg > --- > block/blk-mq.c | 66 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 4 +++ > 2 files changed, 70 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index abcf590f6238..c37e37354330 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -209,6 +209,42 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) > } > EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); > > +static void blk_mq_quiesce_blocking_queue_async(struct request_queue *q) > +{ > + struct blk_mq_hw_ctx *hctx; > + unsigned int i; > + > + blk_mq_quiesce_queue_nowait(q); > + > + queue_for_each_hw_ctx(q, hctx, i) { > + WARN_ON_ONCE(!(hctx->flags & BLK_MQ_F_BLOCKING)); > + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); > + if (!hctx->rcu_sync) > + continue; This approach of quiesce/unquiesce tagset is good abstraction. Just one more thing, please allocate a rcu_sync array because hctx is supposed to not store scratch stuff. thanks, Ming