From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 1E6C165593 for ; Thu, 23 Jul 2020 10:31:50 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 0D9ED26729 for ; Thu, 23 Jul 2020 10:31:20 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id BF72D2671A for ; Thu, 23 Jul 2020 10:31:18 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 84E4D43321 for ; Thu, 23 Jul 2020 10:31:18 +0200 (CEST) To: Proxmox Backup Server development discussion , Stefan Reiter References: <20200722135625.23653-1-s.reiter@proxmox.com> From: Thomas Lamprecht Message-ID: <448db9ae-20e9-2615-b056-d65bae81c11a@proxmox.com> Date: Thu, 23 Jul 2020 10:31:17 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:79.0) Gecko/20100101 Thunderbird/79.0 MIME-Version: 1.0 In-Reply-To: <20200722135625.23653-1-s.reiter@proxmox.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.008 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: [pbs-devel] applied-series: [PATCH v2 0/5] Fix PBS blockdriver for non-VM settings X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Jul 2020 08:31:50 -0000 On 22.07.20 15:56, Stefan Reiter wrote: > When using the PBS blockdriver with qemu-nbd (for example), it can happen that > enough read requests are issued to saturate the tokio thread pool. Not an issue > in general, but as me and Wolfgang painstakenly discovered a while back, it does > break block_on, which is used in BufferedFixedReader. This means that reading > larger amounts of data would hang the QEMU process [0]. > > Fix this by replacing the BufferedFixedReader with an AsyncIndexReader, > implementing AsyncSeek for it in the process. This makes the entire API async, > requiring no block_on anymore. > > Incidentally, this also gave me my best benchmark results yet, coming in at > above 1.6 Gb/s read speed via NBD on my local machine. > > Additionally I discovered a seperate bug (fixed by patch 5), wherein read > requests that we're not aligned to the chunk size would return bogus data. This > too only seems to happen in non-VM connections (e.g. nbd, etc...). > > v2: > * Remove BufferedFixedReader entirely, use AsyncIndexReader instead > * Implement AsyncSeek for AsyncIndexReader > * Fix the second bug in Rust instead of QEMU C > > > [0] ...and since the NBD kernel driver appears to be horribly broken, this often > also crashes most of the system, but that's a different story. If you ever get > in this situation, 'nbd-client -d /dev/nbdX' works (sometimes) to force > disconnect the device ('qemu-nbd -d' intelligently issues a read before > disconnecting, thus hanging before getting anything done...) > > > backup: Stefan Reiter (3): > add and implement chunk_from_offset for IndexFile > implement AsyncSeek for AsyncIndexReader > remove BufferedFixedReader interface > > src/backup/async_index_reader.rs | 116 ++++++++++++++++++---- > src/backup/dynamic_index.rs | 18 ++++ > src/backup/fixed_index.rs | 165 +++---------------------------- > src/backup/index.rs | 4 + > 4 files changed, 129 insertions(+), 174 deletions(-) > > backup-qemu: Stefan Reiter (2): > use AsyncIndexReader for read_image_at > read_image_at: iterate until buffer is filled > > current-api.h | 4 ++-- > src/lib.rs | 4 ++-- > src/restore.rs | 35 +++++++++++++++++++++++------------ > 3 files changed, 27 insertions(+), 16 deletions(-) > applied series, thanks! using the noload mount option is really the key here, for ext4 at least ^^ # mount -o noload /dev/nbd0p1 /mnt/foo