[pve-devel] [PATCH docs 0/4] qm: more visible recommendations for virtio devices/controllers

[pve-devel] [PATCH docs 0/4] qm: more visible recommendations for virtio devices/controllers

[Fiona Ebner]

Also, updates the section for the SCSI controller to mention the
current default.

Fiona Ebner (4):
  qm: hard disk controllers: reword and update section
  qm: hard disk controllers: recommend VirtIO controllers
  qm: emulated devices: mention that virtio devices are better
    maintained
  qm: emulated devices: make recommendation for virtio devices more
    visible

 qm.adoc | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

-- 
2.30.2

[pve-devel] [PATCH docs 1/4] qm: hard disk controllers: reword and update section

[Fiona Ebner]

Most importantly, mention that VirtIO SCSI single in combination with
IO thread is the new recommendation and default. The controller type
used for the QEMU commandline is still the same (but one for each
disk), so information about when OSes started supporting it should be
accurate.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 qm.adoc | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/qm.adoc b/qm.adoc
index 8a49283..629e913 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -169,16 +169,15 @@ connected. You can connect up to 6 devices on this controller.
 hardware, and can connect up to 14 storage devices. {pve} emulates by default a
 LSI 53C895A controller.
 +
-A SCSI controller of type _VirtIO SCSI_ is the recommended setting if you aim for
-performance and is automatically selected for newly created Linux VMs since
-{pve} 4.3. Linux distributions have support for this controller since 2012, and
-FreeBSD since 2014. For Windows OSes, you need to provide an extra iso
-containing the drivers during the installation.
+A SCSI controller of type _VirtIO SCSI single_ and enabling the
+xref:qm_hard_disk_iothread[IO Thread] setting for the attached disks is
+recommended if you aim for performance. This is the default for newly created
+Linux VMs since {pve} 7.3. Each disk will have its own _VirtIO SCSI_ controller,
+and QEMU will handle the disks IO in a dedicated thread. Linux distributions
+have support for this controller since 2012, and FreeBSD since 2014. For Windows
+OSes, you need to provide an extra ISO containing the drivers during the
+installation.
 // https://pve.proxmox.com/wiki/Paravirtualized_Block_Drivers_for_Windows#During_windows_installation.
-If you aim at maximum performance, you can select a SCSI controller of type
-_VirtIO SCSI single_ which will allow you to select the *IO Thread* option.
-When selecting _VirtIO SCSI single_ QEMU will create a new controller for
-each disk, instead of adding all disks to the same controller.
 
 * The *VirtIO Block* controller, often just called VirtIO or virtio-blk,
 is an older type of paravirtualized controller. It has been superseded by the
-- 
2.30.2

[pve-devel] [PATCH docs 2/4] qm: hard disk controllers: recommend VirtIO controllers

[Fiona Ebner]

Quoting from [0]:
> In general, I advise against using AHCI in production as better
> performance (and dev support) can be achieved through virtio.

[0]: https://lists.nongnu.org/archive/html/qemu-devel/2023-02/msg03915.html

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 qm.adoc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/qm.adoc b/qm.adoc
index 629e913..6fc6f5e 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -155,6 +155,9 @@ Bus/Controller
 ^^^^^^^^^^^^^^
 QEMU can emulate a number of storage controllers:
 
+TIP: It is highly recommended to use the *VirtIO SCSI* or *VirtIO Block*
+controller for performance reasons and because they are better maintained.
+
 * the *IDE* controller, has a design which goes back to the 1984 PC/AT disk
 controller. Even if this controller has been superseded by recent designs,
 each and every OS you can think of has support for it, making it a great choice
-- 
2.30.2

[pve-devel] [PATCH docs 3/4] qm: emulated devices: mention that virtio devices are better maintained

[Fiona Ebner]

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 qm.adoc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/qm.adoc b/qm.adoc
index 6fc6f5e..c3865cb 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -80,12 +80,12 @@ controller, a paravirtualized network card, a paravirtualized serial port,
 a paravirtualized SCSI controller, etc ...
 
 It is highly recommended to use the virtio devices whenever you can, as they
-provide a big performance improvement. Using  the virtio generic disk controller
-versus an emulated IDE controller will double the sequential write throughput,
-as measured with `bonnie++(8)`. Using the virtio network interface can deliver
-up to three times the throughput of an emulated Intel E1000 network card, as
-measured with `iperf(1)`. footnote:[See this benchmark on the KVM wiki
-https://www.linux-kvm.org/page/Using_VirtIO_NIC]
+provide a big performance improvement and are generally better maintained. Using
+the virtio generic disk controller versus an emulated IDE controller will double
+the sequential write throughput, as measured with `bonnie++(8)`. Using the
+virtio network interface can deliver up to three times the throughput of an
+emulated Intel E1000 network card, as measured with `iperf(1)`. footnote:[See
+this benchmark on the KVM wiki https://www.linux-kvm.org/page/Using_VirtIO_NIC]
 
 
 [[qm_virtual_machines_settings]]
-- 
2.30.2

[pve-devel] [PATCH docs 4/4] qm: emulated devices: make recommendation for virtio devices more visible

[Fiona Ebner]

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 qm.adoc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/qm.adoc b/qm.adoc
index c3865cb..bd535a2 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -79,11 +79,11 @@ paravirtualized virtio devices, which includes a paravirtualized generic disk
 controller, a paravirtualized network card, a paravirtualized serial port,
 a paravirtualized SCSI controller, etc ...
 
-It is highly recommended to use the virtio devices whenever you can, as they
-provide a big performance improvement and are generally better maintained. Using
-the virtio generic disk controller versus an emulated IDE controller will double
-the sequential write throughput, as measured with `bonnie++(8)`. Using the
-virtio network interface can deliver up to three times the throughput of an
+TIP: It is *highly recommended* to use the virtio devices whenever you can, as
+they provide a big performance improvement and are generally better maintained.
+Using the virtio generic disk controller versus an emulated IDE controller will
+double the sequential write throughput, as measured with `bonnie++(8)`. Using
+the virtio network interface can deliver up to three times the throughput of an
 emulated Intel E1000 network card, as measured with `iperf(1)`. footnote:[See
 this benchmark on the KVM wiki https://www.linux-kvm.org/page/Using_VirtIO_NIC]
 
-- 
2.30.2

[pve-devel] applied-series: [PATCH docs 0/4] qm: more visible recommendations for virtio devices/controllers

[Thomas Lamprecht]

On 17/02/2023 17:08, Fiona Ebner wrote:
> Also, updates the section for the SCSI controller to mention the
> current default.
> 
> Fiona Ebner (4):
>   qm: hard disk controllers: reword and update section
>   qm: hard disk controllers: recommend VirtIO controllers
>   qm: emulated devices: mention that virtio devices are better
>     maintained
>   qm: emulated devices: make recommendation for virtio devices more
>     visible
> 
>  qm.adoc | 34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
> 


applied series, thanks!