From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate001.proxmox.com (gate001.proxmox.com [IPv6:2a0f:8001:1:32::40]) by lore.proxmox.com (Postfix) with ESMTPS id D3ADB1FF0BA for ; Thu, 20 Aug 2026 11:05:53 +0200 (CEST) Received: from gate001.proxmox.com (localhost.localdomain [127.0.0.1]) by gate001.proxmox.com (Proxmox) with ESMTP id F19BA21597; Thu, 20 Aug 2026 11:05:49 +0200 (CEST) From: Christian Ebner To: pve-devel@lists.proxmox.com Subject: [PATCH v3 pve-qemu qemu-server 0/6] bypass host page cache for restore on zvol Date: Thu, 20 Aug 2026 11:05:22 +0200 Message-ID: <20260820090528.117853-1-c.ebner@proxmox.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1787216717753 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.775 Adjusted score from AWL reputation of From: address DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment (newer systems) 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 Message-ID-Hash: CKKRZVDNBA55QLML3CJGBO47R57AB2BJ X-Message-ID-Hash: CKKRZVDNBA55QLML3CJGBO47R57AB2BJ X-MailFrom: c.ebner@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox VE development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: This patch series skips writing to the host page cache for restores to zvols, with the intention to avoid potential I/O delay issues for other ZFS-backed VMs during page writeback on certain setups, as reported in enterprise support and reproduced internally. This patch series adds an optional no-cache parameter for pbs-restore command invocation, setting the BDRV_O_NOCACHE flag for the block device being restored to and sets `cache=none` for vma restores. Since this seems to affect only zvol's, conditionally set the flag only during restores to storages with type `zfspool`. pve-qemu: Christian Ebner (1): pbs-restore: add optional no-cache flag to bypass host page cache ...no-cache-flag-to-skip-host-page-cach.patch | 72 +++++++++++++++++++ debian/patches/series | 1 + 2 files changed, 73 insertions(+) create mode 100644 debian/patches/pve/0047-pbs-restore-add-no-cache-flag-to-skip-host-page-cach.patch qemu-server: Christian Ebner (5): helpers: never cache `unknown` on failed kvm binary version check helpers: optionally get package version for kvm_user_version() helpers: add helper for min kvm package version comparison pbs-restore: set 'no-cache' on block devices backed by zfspool vma restore: skip page cache on block devices backed by zfspool src/PVE/QemuServer.pm | 21 +++++++++++++++++- src/PVE/QemuServer/Helpers.pm | 41 ++++++++++++++++++++++++++++------- 2 files changed, 53 insertions(+), 9 deletions(-) -- 2.47.3