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(p200300cbc70b1600c48b1faba3305182.dip0.t-ipconnect.de. [2003:cb:c70b:1600:c48b:1fab:a330:5182]) by smtp.gmail.com with ESMTPSA id e20-20020a5d5954000000b0021e42e7c7dbsm13645977wri.83.2022.08.23.01.01.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Aug 2022 01:02:01 -0700 (PDT) Message-ID: Date: Tue, 23 Aug 2022 10:01:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Content-Language: en-US To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Paolo Bonzini , "Denis V. Lunev" , Peter Xu , Yanan Wang , Marcel Apfelbaum , "Richard W.M. Jones" , qemu-block@nongnu.org, John Snow , integration@gluster.org, Vladimir Sementsov-Ogievskiy , Vladimir Sementsov-Ogievskiy , Laurent Vivier , Markus Armbruster , Raphael Norwitz , Richard Henderson , Fam Zheng , sgarzare@redhat.com, Alberto Faria , Kevin Wolf , Wen Congyang , Eric Blake , Hanna Reitz , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Eduardo Habkost , "Michael S. Tsirkin" , Thomas Huth , Jeff Cody , Xie Changlong References: <20220822222402.176088-1-stefanha@redhat.com> <20220822222402.176088-12-stefanha@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [RFC v4 11/11] virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint In-Reply-To: <20220822222402.176088-12-stefanha@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23.08.22 00:24, Stefan Hajnoczi wrote: > Register guest RAM using BlockRAMRegistrar and set the > BDRV_REQ_REGISTERED_BUF flag so block drivers can optimize memory > accesses in I/O requests. > > This is for vdpa-blk, vhost-user-blk, and other I/O interfaces that rely > on DMA mapping/unmapping. Can you explain why we're monitoring RAMRegistrar to hook into "guest RAM" and not go the usual path of the MemoryListener? What will BDRV_REQ_REGISTERED_BUF actually do? Pin all guest memory in the worst case such as io_uring fixed buffers would do ( I hope not ). -- Thanks, David / dhildenb