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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 F3DF2ECDFD0 for ; Fri, 14 Sep 2018 13:08:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A94D020853 for ; Fri, 14 Sep 2018 13:08:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A94D020853 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728133AbeINSXR (ORCPT ); Fri, 14 Sep 2018 14:23:17 -0400 Received: from mga03.intel.com ([134.134.136.65]:35734 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727773AbeINSXR (ORCPT ); Fri, 14 Sep 2018 14:23:17 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Sep 2018 06:08:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,373,1531810800"; d="scan'208";a="90034859" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.98]) ([10.237.72.98]) by fmsmga001.fm.intel.com with ESMTP; 14 Sep 2018 06:05:10 -0700 Subject: Re: [PATCH RFC] scsi: ufs: Disable blk-mq for now To: Ming Lei Cc: "Martin K . Petersen" , "James E . J . Bottomley" , Jens Axboe , Christoph Hellwig , Johannes Thumshirn , Bart Van Assche , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Stanislav Nijnikov , Evan Green , Vinayak Holikatti , Janek Kotas , Vivek Gautam , Asutosh Das , Subhash Jadavani , Sayali Lokhande , Li Wei , Bjorn Andersson , Jaegeuk Kim , Alim Akhtar , Alex Lemberg References: <20180913112848.7807-1-adrian.hunter@intel.com> <20180913120459.GA4965@ming.t460p> <20180914015237.GC11059@ming.t460p> <2fdfc038-5b86-243c-9b0a-f294d281e5c0@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Fri, 14 Sep 2018 16:03:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <2fdfc038-5b86-243c-9b0a-f294d281e5c0@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/09/18 09:17, Adrian Hunter wrote: > On 14/09/18 04:52, Ming Lei wrote: >> On Thu, Sep 13, 2018 at 03:15:39PM +0300, Adrian Hunter wrote: >>> On 13/09/18 15:05, Ming Lei wrote: >>>> On Thu, Sep 13, 2018 at 02:28:48PM +0300, Adrian Hunter wrote: >>>>> blk-mq does not support runtime pm, so disable blk-mq support for now. >>>> >>>> So could you describe a bit what the issue you are trying to fix? >>> >>> UFS is a low-power solution, so we must be able to runtime suspend. >>> >>>> >>>> This is host level runtime PM you are trying to address, and if blk-mq >>>> runtime isn't enabled, I guess the host won't be runtime suspended at all >>>> because some of its descendant are always active. >>>> >>>> So seems we need to do nothing for preventing the host controller from >>>> entering runtime suspend. >>> >>> We don't want to prevent the host controller from runtime suspending, quite >>> the opposite. >> >> OK, got it. >> >> However, in previous discussion, it is strongly objected to use >> per-driver/device .use_blk_mq switch, so not sure if this way can >> be accepted. > > It is only needed for 4.19 so far. Otherwise just revert d5038a13eca7 > ("scsi: core: switch to scsi-mq by default") > >> >> BTW, I just posted the runtime PM enablement patches[1] for blk-mq, >> and I verified that it works fine and passed blktests & xfstest & my >> other sanity tests, could you try it on UFS? >> >> [1] https://marc.info/?l=linux-block&m=153684095523409&w=2 > > I will give it a go. Yes it seemed to work fine for UFS Tested-by: Adrian Hunter > > Obviously, if those patches go in, we wouldn't need to disable blk-mq > anymore, but that isn't until 4.20 at least. >