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[5.186.124.214]) by smtp.gmail.com with ESMTPSA id x15sm16783915edj.91.2020.12.08.04.22.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Dec 2020 04:22:49 -0800 (PST) Date: Tue, 8 Dec 2020 13:22:48 +0100 From: Javier =?utf-8?B?R29uesOhbGV6?= To: Johannes Thumshirn Cc: Hannes Reinecke , Christoph Hellwig , SelvaKumar S , "linux-nvme@lists.infradead.org" , "kbusch@kernel.org" , "axboe@kernel.dk" , Damien Le Moal , "sagi@grimberg.me" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "dm-devel@redhat.com" , "snitzer@redhat.com" , "selvajove@gmail.com" , "nj.shetty@samsung.com" , "joshi.k@samsung.com" , "Martin K. Petersen" , Bart Van Assche , Mikulas Patocka , "linux-scsi@vger.kernel.org" Subject: Re: [RFC PATCH v2 0/2] add simple copy support Message-ID: <20201208122248.utv7pqthmmn6uwv6@mpHalley> References: <20201204094659.12732-1-selvakuma.s1@samsung.com> <20201207141123.GC31159@lst.de> <01fe46ac-16a5-d4db-f23d-07a03d3935f3@suse.de> <20201207192453.vc6clbdhz73hzs7l@mpHalley> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 08.12.2020 08:40, Johannes Thumshirn wrote: >On 07/12/2020 20:27, Javier González wrote: >> Good point. We can share some performance data on how Simple Copy scales >> in terms of bw / latency and the CPU usage. Do you have anything else in >> mind? >> > >With an emulation in the kernel, we could make the usd "backend" >implementation configurable. So if the emulation is faster, users can select >the emulation, if the device is faster then the device. > >Kind of what the crypto and raid code do as well. Good idea. Are you thinking of a sysfs entry to select the backend? > >I'm really interested in this work, as BTRFS relocation/balance will have >potential benefits, but we need to get it right. Agree. We will post a V3 with emulation and addressing other comments. We can take it from there. If you have comments on V2, please send them our way and we will take them in.