From: Dominik Budzowski <dbudzowski@alfaline.pl>
To: pve-devel@lists.proxmox.com
Subject: [pve-devel] [PATCH qemu-server] Add iothread_vq_mapping support for virtio-blk (PVE 8.4)
Date: Thu, 26 Jun 2025 00:15:34 +0200 [thread overview]
Message-ID: <20250625221535.1688870-1-dbudzowski@alfaline.pl> (raw)
Cover letter for series of patches adding iothread_vq_mapping support to
virtio-blk devices in Proxmox VE 8.4.
This feature was introduced in QEMU 9 and allows mapping multiple vhost
queues onto separate IO threads, dramatically improving RAW block I/O
throughput.
See discussion and background here:
https://blogs.oracle.com/linux/post/virtioblk-using-iothread-vq-mapping
Patches:
1. drive-iothread-vq-pve8.4.patch
– extend PVE/QemuServer/Drive.pm to expose `iothread_vq_mapping`
parameter in `Drive` objects.
2. qemuserver-iothread-vq-pve8.4.patch
– update PVE/QemuServer.pm to consume `iothread_vq_mapping`,
generate `-object iothread,id=…` entries and JSON `-device`
parameters with separate bus/addr fields.
Installation:
cp /usr/share/perl5/PVE/QemuServer/Drive.pm \
/usr/share/perl5/PVE/QemuServer/Drive.pm.backup
cp /usr/share/perl5/PVE/QemuServer.pm \
/usr/share/perl5/PVE/QemuServer.pm.backup
patch /usr/share/perl5/PVE/QemuServer/Drive.pm \
< drive-iothread-vq-pve8.4.patch
patch /usr/share/perl5/PVE/QemuServer.pm \
< qemuserver-iothread-vq-pve8.4.patch
systemctl restart pvedaemon pveproxy
Usage:
Add `iothread_vq_mapping=<num>` (2–16) to your disk line in
`/etc/pve/qemu-server/<VMID>.conf`, for example:
virtio0: local-lvm:vm-100-disk-0,aio=native,iothread_vq_mapping=8,size=50G
Test Results:
fio 4k randread RAW:
- legacy `iothread=1`: ~200k IOPS
- new `iothread_vq_mapping=8`: ~800k IOPS
Please review this series to bring enhanced virtio-blk performance to PVE 8.4.
—
Dominik Budzowski <dbudzowski@alfaline.pl>
Signed-off-by: Dominik Budzowski <dbudzowski@alfaline.pl>
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next reply other threads:[~2025-06-25 22:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-25 22:15 Dominik Budzowski [this message]
2025-06-25 22:15 ` [pve-devel] [PATCH] Add patches for iothread_vq Dominik Budzowski
2025-06-27 7:01 ` DERUMIER, Alexandre via pve-devel
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