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=-4.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 113F1C433DF for ; Thu, 2 Jul 2020 10:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E45F620780 for ; Thu, 2 Jul 2020 10:22:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=javigon-com.20150623.gappssmtp.com header.i=@javigon-com.20150623.gappssmtp.com header.b="eS2AS63X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728147AbgGBKWA (ORCPT ); Thu, 2 Jul 2020 06:22:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728397AbgGBKUp (ORCPT ); Thu, 2 Jul 2020 06:20:45 -0400 Received: from mail-ej1-x642.google.com (mail-ej1-x642.google.com [IPv6:2a00:1450:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE0B9C08C5C1 for ; Thu, 2 Jul 2020 03:20:44 -0700 (PDT) Received: by mail-ej1-x642.google.com with SMTP id p20so28615894ejd.13 for ; Thu, 02 Jul 2020 03:20:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=javigon-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=y6QK1uUJZHQuZnFXHjM7RpcCfhjO+BnMr6K6R14LikI=; b=eS2AS63X4xHtWcaWVJuiQnZRL3FS5hl/kitkp/qfhE2U4bn44KsMkcI5ahaIUhkpta 6tvJeM0eRhhkkdT/HtD13QyqAXZlJuuAf/hOLUhwUyrVhrIjZLI2hfSmgt0Q4v08rWWl 8hS+jEqsMJSVlJnAruXLO3In7Lsa86+0XITBf7uyOLIOrdOeks10qjwobA7CaPzU54OH mdateSDMB8KYldO8l84nBECnC0GG8g0k4bICDJTD3s+k3LkuNDtPYYV+0R3HUmtsZXuS e9+cfSLqkoMb/HgGnCCw/eX3Iyfs42vr/mrFfAeVgD77VV9daKXn2j6SDsAxfRoi+XfU Ak+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=y6QK1uUJZHQuZnFXHjM7RpcCfhjO+BnMr6K6R14LikI=; b=t1F/bEQ3rQX6tM8hHOimddvs052GIOVAEPtNaf95XhkdPtJSPob148KGAllRRp+do0 4QHLd0gKaT7dxezUWlRp1pRNB5kpCXWIR9RtilImVvW2ukDKXLkLBsSx9kMdqN8bJqGc 9U+Ka6kOIBVcEdJY2VftH4yJ+rbUeoalPJ1FXvCTu+GphgNakiORr9lkrPs9Xa9ArF3y dwzobfGb/KCfP6I0C96ncoPI4YN3vyMP6wLIJPjluw9P8tVtOU60t0NBXk30phvRKNZO 4ucZr0qieHosrlfJTEokUqNB4SlHkiBwdXQdO1SU367A+24Q9y9wEPU/UFH6mJsT41Fv t3Nw== X-Gm-Message-State: AOAM533ce1L+TVsNSlubQCUARbPRwEkxTmiEoeZ0S6dbY/8uWy9xEasb kpDYNW7T87fCBhUqzTOUf/CKig== X-Google-Smtp-Source: ABdhPJznU0cTuSpy44OchlJ/NcoicUfXVthk+RD4AWFPMdlv1FyVBTAxmHOyydYRtWmTGe2aRm0ZCQ== X-Received: by 2002:a17:906:c142:: with SMTP id dp2mr28125124ejc.541.1593685243381; Thu, 02 Jul 2020 03:20:43 -0700 (PDT) Received: from localhost ([194.62.217.57]) by smtp.gmail.com with ESMTPSA id dh16sm9185934edb.3.2020.07.02.03.20.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jul 2020 03:20:42 -0700 (PDT) Date: Thu, 2 Jul 2020 12:20:41 +0200 From: Javier =?utf-8?B?R29uesOhbGV6?= To: Niklas Cassel Cc: Jonathan Corbet , Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , "James E.J. Bottomley" , "Martin K. Petersen" , "linux-scsi@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" Subject: Re: [PATCH 2/2] block: add max_active_zones to blk-sysfs Message-ID: <20200702102041.qlehlokxel5ed6sf@mpHalley.local> References: <20200616102546.491961-1-niklas.cassel@wdc.com> <20200616102546.491961-3-niklas.cassel@wdc.com> <20200701111330.3vpivrovh3i46maa@mpHalley.local> <20200702084104.GA607715@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200702084104.GA607715@localhost.localdomain> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 02.07.2020 08:41, Niklas Cassel wrote: >On Wed, Jul 01, 2020 at 01:16:52PM +0200, Javier González wrote: >> On 16.06.2020 12:25, Niklas Cassel wrote: >> > Add a new max_active zones definition in the sysfs documentation. >> > This definition will be common for all devices utilizing the zoned block >> > device support in the kernel. >> > >> > Export max_active_zones according to this new definition for NVMe Zoned >> > Namespace devices, ZAC ATA devices (which are treated as SCSI devices by >> > the kernel), and ZBC SCSI devices. >> > >> > Add the new max_active_zones struct member to the request_queue, rather >> > than as a queue limit, since this property cannot be split across stacking >> > drivers. >> > >> > For SCSI devices, even though max active zones is not part of the ZBC/ZAC >> > spec, export max_active_zones as 0, signifying "no limit". >> > >> > Signed-off-by: Niklas Cassel >> > --- > >(snip) > >> Looking a second time at these patches, wouldn't it make sense to move >> this to queue_limits? > >Hello Javier, > >The problem with having MAR/MOR as queue_limits, is that they >then would be split across stacking drivers/device-mapper targets. >However, MAR/MOR are not splittable, at least not the way the >block layer works today. > >If the block layer and drivers ever change so that they do >accounting of zone conditions, then we could divide the MAR/MOR to >be split over stacking drivers, but because of performance reasons, >this will probably never happen. >In the unlikely event that it did happen, we would still use the >same sysfs-path for these properties, the only thing that would >change would be that these would be moved into queue_limits. > > >So the way the code looks right now, these properties cannot >be split, therefore I chose to put them inside request_queue >(just like nr_zones), rather than request_queue->limits >(which is of type struct queue_limits). > >nr_zones is also exposed as a sysfs property, even though it >is part of request_queue, so I don't see why MAR/MOR can't do >the same. Also see Damien's replies to PATCH 1/2 of this series, >which reaches the same conclusion. > Thanks for explaining Niklas - makes sense. I just looked at your patch again while adding other attributes and thought it would be worth asking the reason behind it. You can keep the reviewed-by on the 2 patches. Javier