From: Jonas Theisen <j.theisen@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: Re: [PATCH v2 qemu-server 0/5] bypass host page cache for restore on zvol
Date: Wed, 19 Aug 2026 18:44:49 +0200 [thread overview]
Message-ID: <87fd3468-358b-43cb-a035-9f38dfc11fe4@proxmox.com> (raw)
In-Reply-To: <20260819144642.453513-1-c.ebner@proxmox.com>
On 8/19/26 16:46, Christian Ebner wrote:
> 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`.
>
> [snip]
Tested this patch on a lab host with a restore from PBS on the same host.
Seeing no relevant I/O delays on a zvol on the same pool.
VMs hosted on the same pool also experience only marginal delays.
--
Tested-by: Jonas Theisen <j.theisen@proxmox.com>
next prev parent reply other threads:[~2026-08-19 16:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-19 14:46 [PATCH v2 qemu-server 0/5] bypass host page cache for restore on zvol Christian Ebner
2026-08-19 14:46 ` [PATCH v2 pve-qemu 1/5] add optional no-cache flag to bypass host page cache on pbs-restore Christian Ebner
2026-08-19 16:44 ` Fiona Ebner
2026-08-19 14:46 ` [PATCH v2 qemu-server 2/5] helpers: optionally get package version for kvm_user_version() Christian Ebner
2026-08-19 16:37 ` Fiona Ebner
2026-08-19 14:46 ` [PATCH v2 qemu-server 3/5] helpers: add helper for min package version comparison Christian Ebner
2026-08-19 16:37 ` Fiona Ebner
2026-08-19 14:46 ` [PATCH v2 qemu-server 4/5] pbs-restore: set 'no-cache' on block devices backed by zfspool Christian Ebner
2026-08-19 14:46 ` [PATCH v2 qemu-server 5/5] vma restore: skip page cache " Christian Ebner
2026-08-19 16:44 ` Jonas Theisen [this message]
2026-08-20 9:06 ` [PATCH v2 qemu-server 0/5] bypass host page cache for restore on zvol Christian Ebner
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