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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E49B9C4332F for ; Fri, 4 Feb 2022 16:01:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376348AbiBDQBr (ORCPT ); Fri, 4 Feb 2022 11:01:47 -0500 Received: from verein.lst.de ([213.95.11.211]:41815 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231664AbiBDQBq (ORCPT ); Fri, 4 Feb 2022 11:01:46 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 9C75E68AA6; Fri, 4 Feb 2022 17:01:40 +0100 (CET) Date: Fri, 4 Feb 2022 17:01:40 +0100 From: Christoph Hellwig To: Hannes Reinecke Cc: Chaitanya Kulkarni , Javier =?iso-8859-1?Q?Gonz=E1lez?= , Damien Le Moal , Luis Chamberlain , Mikulas Patocka , "linux-block@vger.kernel.org" , Keith Busch , Adam Manzanares , "linux-scsi@vger.kernel.org" , "dm-devel@redhat.com" , "linux-nvme@lists.infradead.org" , linux-fsdevel , Jens Axboe , "msnitzer@redhat.com >> msnitzer@redhat.com" , Bart Van Assche , "martin.petersen@oracle.com >> Martin K. Petersen" , "roland@purestorage.com" , Christoph Hellwig , "Frederick.Knight@netapp.com" , "zach.brown@ni.com" , "osandov@fb.com" , "lsf-pc@lists.linux-foundation.org" , "djwong@kernel.org" , "josef@toxicpanda.com" , "clm@fb.com" , "dsterba@suse.com" , "tytso@mit.edu" , "jack@suse.com" , Kanchan Joshi Subject: Re: [RFC PATCH 3/3] nvme: add the "debug" host driver Message-ID: <20220204160140.GA6817@lst.de> References: <20220203153843.szbd4n65ru4fx5hx@garbanzo> <20220203165238.GA142129@dhcp-10-100-145-180.wdc.com> <20220203195155.GB249665@bgt-140510-bm01> <863d85e3-9a93-4d8c-cf04-88090eb4cc02@nvidia.com> <2bbed027-b9a1-e5db-3a3d-90c40af49e09@opensource.wdc.com> <9d5d0b50-2936-eac3-12d3-a309389e03bf@nvidia.com> <20220204082445.hczdiy2uhxfi3x2g@ArmHalley.local> <4d5410a5-93c3-d73c-6aeb-2c1c7f940963@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Feb 04, 2022 at 03:15:02PM +0100, Hannes Reinecke wrote: >> ZNS kernel code testing is also done on QEMU, I've also fixed >> bugs in the ZNS kernel code which are discovered on QEMU and I've not >> seen any issues with that. Given that simple copy feature is way smaller >> than ZNS it will less likely to suffer from slowness and etc (listed >> above) in QEMU. >> >> my point is if we allow one, we will be opening floodgates and we need >> to be careful not to bloat the code unless it is _absolutely >> necessary_ which I don't think it is based on the simple copy >> specification. >> > > I do have a slightly different view on the nvme target code; it should > provide the necessary means to test the nvme host code. > And simple copy is on of these features, especially as it will operate as > an exploiter of the new functionality. Well, in general I'd like to have every useful feature supported in nvmet, because it serves both testing and production. If a feature isn't all that useful (and there are lots of those in nvme these days) we don't need to support in nvmet, but probably neither in the host code.