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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 EA8BBC33CA2 for ; Fri, 10 Jan 2020 02:00:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C15A02064C for ; Fri, 10 Jan 2020 02:00:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fn6VlKK3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730708AbgAJCA7 (ORCPT ); Thu, 9 Jan 2020 21:00:59 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:58108 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730619AbgAJCA6 (ORCPT ); Thu, 9 Jan 2020 21:00:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578621657; 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=TIpC/krxLydDnHVW/RNCGJrbKjBHiQ/9nuaNV71WzMg=; b=fn6VlKK326yL3AQdehoZKHQxh6rb3VC9/32G+c8iFrphi5UhOIkpO6Ghu3LIDXIGWIL8DL 9Begjm+iHjvyBIrJo5USgZXwpR3DKsKWSidzd45SmdjGRZJzn1w5PzCJG1RrlrON3OiiHx HkB61u58FHl0YGBOplOtUEEKACWISK4= 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-253-2IjvPvvuNNqdHnpMOhEJtA-1; Thu, 09 Jan 2020 21:00:53 -0500 X-MC-Unique: 2IjvPvvuNNqdHnpMOhEJtA-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1565B1800D4E; Fri, 10 Jan 2020 02:00:51 +0000 (UTC) Received: from ming.t460p (ovpn-8-24.pek2.redhat.com [10.72.8.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8ADE486CA7; Fri, 10 Jan 2020 02:00:42 +0000 (UTC) Date: Fri, 10 Jan 2020 10:00:38 +0800 From: Ming Lei To: John Garry Cc: Sumit Saxena , Hannes Reinecke , "Martin K. Petersen" , Jens Axboe , Christoph Hellwig , James Bottomley , Linux SCSI List , linux-block@vger.kernel.org, Hannes Reinecke Subject: Re: [PATCH 09/11] megaraid_sas: switch fusion adapters to MQ Message-ID: <20200110020038.GB4501@ming.t460p> References: <20191202153914.84722-1-hare@suse.de> <20191202153914.84722-10-hare@suse.de> <339f089f-26aa-1cbe-416b-67809ea6791f@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <339f089f-26aa-1cbe-416b-67809ea6791f@huawei.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jan 09, 2020 at 11:55:12AM +0000, John Garry wrote: > On 09/12/2019 10:10, Sumit Saxena wrote: > > On Mon, Dec 2, 2019 at 9:09 PM Hannes Reinecke wrote: > > > > > > Fusion adapters can steer completions to individual queues, and > > > we now have support for shared host-wide tags. > > > So we can enable multiqueue support for fusion adapters and > > > drop the hand-crafted interrupt affinity settings. > > > > Hi Hannes, > > > > Ming Lei also proposed similar changes in megaraid_sas driver some > > time back and it had resulted in performance drop- > > https://patchwork.kernel.org/patch/10969511/ > > > > So, we will do some performance tests with this patch and update you. > > > > Hi Sumit, > > I was wondering if you had a chance to do this test yet? > > It would be good to know, so we can try to progress this work. Looks most of the comment in the following link isn't addressed: https://lore.kernel.org/linux-block/20191129002540.GA1829@ming.t460p/ > Firstly too much((nr_hw_queues - 1) times) memory is wasted. Secondly IO > latency could be increased by too deep scheduler queue depth. Finally CPU > could be wasted in the retrying of running busy hw queue. > > Wrt. driver tags, this patch may be worse, given the average limit for > each LUN is reduced by (nr_hw_queues) times, see hctx_may_queue(). > > Another change is bt_wait_ptr(). Before your patches, there is single > .wait_index, now the number of .wait_index is changed to nr_hw_queues. > > Also the run queue number is increased a lot in SCSI's IO completion, see > scsi_end_request(). I guess memory waste won't be a blocker. But it may not be one accepted behavior to reduce average active queue depth for each LUN by nr_hw_queues times, meantime scheduler queue depth is increased by nr_hw_queues times, compared with single queue. thanks, Ming