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[23.128.96.18]) by mx.google.com with ESMTP id v3si671512ejb.659.2020.08.19.23.46.30; Wed, 19 Aug 2020 23:46:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@javigon-com.20150623.gappssmtp.com header.s=20150623 header.b=IT6+PQy6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725925AbgHTGpb (ORCPT + 99 others); Thu, 20 Aug 2020 02:45:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725797AbgHTGp3 (ORCPT ); Thu, 20 Aug 2020 02:45:29 -0400 Received: from mail-ej1-x641.google.com (mail-ej1-x641.google.com [IPv6:2a00:1450:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39CB5C061757 for ; Wed, 19 Aug 2020 23:45:29 -0700 (PDT) Received: by mail-ej1-x641.google.com with SMTP id bo3so1206832ejb.11 for ; Wed, 19 Aug 2020 23:45:29 -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:in-reply-to; bh=B2y41juScN4ZEMe70aXDJO6X28WGacc1jO+T2JLh1b0=; b=IT6+PQy6X4iz+w6Eh7CIYhS3hgDl484sGcro3drqzFgNAve9mQvrXDPT4j/INV1mWP GNQdYmVU8BqCQmj6s0p1d8/uTlSbX6e2uea2PEm7J3Tu7GiY8I3o2fbSFOPcRK6++7sY d4Rj3txdjLkVxkoMMw67PHhFtOslq8uZyK9SLWwAj0eUOa5wLZI/Ta8HoEzd0KKsBK3C zs6qS0xTNbyXhG8OASIlwWNKIfluhxcIK3KQmi2GZ7fq74HEo4vMCljrYlhyc0rCSl1C NwZf14AlOcXz37b37RbFiX4Yi4Gj+o+6Gv6q1cqpXpdiAaLAuicEhK8PJW98v+C799NB crOA== 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:in-reply-to; bh=B2y41juScN4ZEMe70aXDJO6X28WGacc1jO+T2JLh1b0=; b=qp+0rDYycqvRoiiPccKPKyg2Vmt+JFQvBaqJ4VPyNMTxnzxY8hopUILrG5RAO+EJZj mqVvCba9cCyC+JlMp47Ql9p7fJXbysDc3OWYxnMltxMsxGHT2iOUcndJSgksM/IhtW5q TcUoe1c5wAFgdubQeZm4oNy/hyJQCi/H26D4qYMLiNNhh3+zrupfOUNwCU10LUKvblWD 9XRSWbj/YyeEhaQ8zhSBWcHWPWHY+NWUdV9El/o6ZlbbPMFOxD65PwREUra0xvLsZu6h 5Ikur0kY65mS8e9j37vvhuIq/tRScrJFihJAtO1zsjwMK8RQXGqrizBygDpywCSTmQ5K SOaQ== X-Gm-Message-State: AOAM5333NzmYL+jYrLt32KlppoHR2NJsCQWYTJsKaEca5sxrRXsOnH8s lIbpB1gtgsyIUdnu2A5WRXTUkg== X-Received: by 2002:a17:906:868a:: with SMTP id g10mr1223275ejx.342.1597905927822; Wed, 19 Aug 2020 23:45:27 -0700 (PDT) Received: from localhost ([194.62.217.57]) by smtp.gmail.com with ESMTPSA id kt27sm819772ejb.15.2020.08.19.23.45.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2020 23:45:26 -0700 (PDT) Date: Thu, 20 Aug 2020 08:45:25 +0200 From: Javier Gonzalez To: Christoph Hellwig Cc: Damien Le Moal , Kanchan Joshi , "kbusch@kernel.org" , "axboe@kernel.dk" , "sagi@grimberg.me" , "linux-nvme@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Johannes Thumshirn , Nitesh Shetty , SelvaKumar S Subject: Re: [PATCH 2/2] nvme: add emulation for zone-append Message-ID: <20200820064525.lae7fnnaiz7rkqvd@MacBook-Pro.localdomain> References: <20200818052936.10995-3-joshi.k@samsung.com> <20200818071249.GB2544@lst.de> <20200818095033.h6ybdwiq3ljagl5a@mpHalley.local> <20200818155004.GA26688@lst.de> <20200818180428.obipue6adpqqpwjj@MacBook-Pro.localdomain> <20200819074035.GA21991@lst.de> <20200819083353.rwblagiesocfcq7i@mpHalley.local> <20200819104349.GA2697@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline In-Reply-To: <20200819104349.GA2697@lst.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19.08.2020 12:43, Christoph Hellwig wrote: >On Wed, Aug 19, 2020 at 09:14:13AM +0000, Damien Le Moal wrote: >> While defining a zone append command for SCSI/ZBC is possible (using sense data >> for returning the written offset), there is no way to define zone append for >> SATA/ZAC without entirely breaking the ATA command model. This is why we went >> after an emulation implementation instead of trying to standardized native >> commands. That implementation does not have any performance impact over regular >> writes *and* zone write locking does not in general degrade HDD write >> performance (only a few corner cases suffer from it). Comparing things equally, >> the same could be said of NVMe drives that do not have zone append native >> support: performance will be essentially the same using regular writes and >> emulated zone append. But mq-deadline and zone write locking will significantly >> lower performance for emulated zone append compared to a native zone append >> support by the drive. > >And to summarize the most important point - Zone Append doesn't exist >in ZAC/ABC. For people that spent the last years trying to make zoned >storage work, the lack of such a primite has been the major pain point. >That's why I came up with the Zone Append design in response to a >request for such an operation from another company that is now heavily >involved in both Linux development and hosting Linux VMs. For ZAC and >ZBC the best we can do is to emulate the approach in the driver, but >for NVMe we can do it. ZNS until just before the release had Zone >Append mandatory, and it did so for a very good reason. While making >it optional allows OEMs to request drives without it, I fundamentally >think we should not support that in Linux and request vendors do >implement writes to zones the right way. Ok. We will just pursue Linux support for the ZNS following the append model. > >And just as some OEMs can request certain TPs or optional features to >be implemented, so can Linux. Just to give an example from the zone >world - Linux requires uniform and power of two zone sizes, which in >ZAC and ZBC are not required.