[pve-devel] [PATCH manager/docs 0/4] fix #2413: make target for ballooning configurable

[pve-devel] [PATCH manager/docs 0/4] fix #2413: make target for ballooning configurable

[Friedrich Weber]

Automatic memory allocation (ballooning) is implemented in pvestatd, which
assigns memory to or reclaims memory from eligible VMs in order to reach a
certain target memory usage on the host. The target is currently hardcoded at
80%. Users have reported [1] that this target is unnecessarily low on hosts
with large amounts of RAM.

This patch series makes the ballooning target configurable. For this, it adds a
new node config option `ballooning-target`. pvestatd then reads the target from
that option.

Some potential discussion points:

- Is it OK to have this as a node option? I imagine some users may want to set
  different targets on different nodes. But other users may want to set one
  target for the whole cluster. Should we have a `ballooning-target` datacenter
  option that can be overridden by a `ballooning-target` node option? This might
  be overkill for such a simple option, though.

- Instead of a `ballooning-target` option, should we go for some general
  `ballooning-settings` with a property string like `target=80`, in case we want
  to make other values (such as `$maxchange`, which is currently hardcoded at 100
  MiB) configurable in the future too?

- In a mixed-version cluster where node 1 has this patch series and node 2
  doesn't yet, any attempt to change node 2's ballooning target from node 1's GUI
  will error out with `ballooning-target: property is not defined in schema`.
  This is not very nice, but not terrible either, as the error message is
  relatively descriptive. Still, is there an easy way to avoid this (checking
  client-side whether the option exists?)

[1] https://bugzilla.proxmox.com/show_bug.cgi?id=2413

manager:

Friedrich Weber (3):
  node: options: add config option for ballooning target
  fix #2413: pvestatd: read ballooning RAM usage target from node config
  ui: node options: allow editing the ballooning RAM usage target

 PVE/NodeConfig.pm                    |  8 ++++++++
 PVE/Service/pvestatd.pm              | 10 +++++++---
 www/manager6/node/NodeOptionsView.js | 18 ++++++++++++++++++
 3 files changed, 33 insertions(+), 3 deletions(-)


docs:

Friedrich Weber (1):
  pvenode: document ballooning-target node option

 pvenode.adoc | 13 +++++++++++++
 qm.adoc      | 13 ++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)


Summary over all repositories:
  5 files changed, 54 insertions(+), 8 deletions(-)

-- 
Generated by git-murpp 0.7.3


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[pve-devel] [PATCH manager 1/4] node: options: add config option for ballooning target

[Friedrich Weber]

The option is intended for the percentage of host memory that pvestatd
uses as the target for automatic memory allocation (ballooning).

Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
---
 PVE/NodeConfig.pm | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/PVE/NodeConfig.pm b/PVE/NodeConfig.pm
index 5f58dff5..d9d83615 100644
--- a/PVE/NodeConfig.pm
+++ b/PVE/NodeConfig.pm
@@ -93,6 +93,14 @@ my $confdesc = {
 	default => 0,
 	optional => 1,
     },
+    'ballooning-target' => {
+	description => 'RAM usage target for ballooning (in percent of total memory)',
+	type => 'integer',
+	minimum => 0,
+	maximum => 100,
+	default => 80,
+	optional => 1,
+    },
 };
 
 my $wakeonlan_desc = {
-- 
2.39.5



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[pve-devel] applied-series: [PATCH manager 1/4] node: options: add config option for ballooning target

[Thomas Lamprecht]

Am 12.03.25 um 16:15 schrieb Friedrich Weber:
> The option is intended for the percentage of host memory that pvestatd
> uses as the target for automatic memory allocation (ballooning).
> 
> Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
> ---
>  PVE/NodeConfig.pm | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
>

applied series, thanks!

Simplified the renderes of node config options in a follow-up.
As we have that `value === undefined ? fallback : value` pattern quite
often it might be good to add a common helper for that, and there I'd
be fine with unconditionally using htmlEncode.


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[pve-devel] [PATCH manager 2/4] fix #2413: pvestatd: read ballooning RAM usage target from node config

[Friedrich Weber]

Currently, the automatic memory management (ballooning) performed by
pvestatd targets 80% memory usage. Users have reported that this
target is unnecessarily low on hosts with large amounts of RAM.

Thus, read the target from the node config option `ballooning-target`.
Also change the ballooning debug log output to include the target.

Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
---
 PVE/Service/pvestatd.pm | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/PVE/Service/pvestatd.pm b/PVE/Service/pvestatd.pm
index 7fa003fe..d80c62da 100755
--- a/PVE/Service/pvestatd.pm
+++ b/PVE/Service/pvestatd.pm
@@ -15,6 +15,7 @@ use PVE::CpuSet;
 use Filesys::Df;
 use PVE::INotify;
 use PVE::Network;
+use PVE::NodeConfig;
 use PVE::Cluster qw(cfs_read_file);
 use PVE::Storage;
 use PVE::QemuServer;
@@ -215,9 +216,12 @@ sub auto_balloning {
     #$hostmeminfo->{memtotal} = int(2*1024*1024*1024/0.8); # you can set this to test
     my $hostfreemem = $hostmeminfo->{memtotal} - $hostmeminfo->{memused};
 
-    # try to use ~80% host memory; goal is the change amount required to achieve that
-    my $goal = int($hostmeminfo->{memtotal} * 0.8 - $hostmeminfo->{memused});
-    $log->("host goal: $goal free: $hostfreemem total: $hostmeminfo->{memtotal}\n");
+    # try to keep host memory usage at a certain percentage (= target), default is 80%
+    my $config = PVE::NodeConfig::load_config($nodename);
+    my $target = int($config->{'ballooning-target'} // 80);
+    # goal is the change amount required to achieve that
+    my $goal = int($hostmeminfo->{memtotal} * $target / 100 - $hostmeminfo->{memused});
+    $log->("target: $target%% host goal: $goal free: $hostfreemem total: $hostmeminfo->{memtotal}\n");
 
     my $maxchange = 100*1024*1024;
     my $res = PVE::AutoBalloon::compute_alg1($vmstatus, $goal, $maxchange);
-- 
2.39.5



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[pve-devel] [PATCH manager 3/4] ui: node options: allow editing the ballooning RAM usage target

[Friedrich Weber]

This corresponds to the `ballooning-target` node config option.

Also make the left column slightly wider, so the texts fit better.

Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
---
 www/manager6/node/NodeOptionsView.js | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/www/manager6/node/NodeOptionsView.js b/www/manager6/node/NodeOptionsView.js
index 661c0e90..53443bfd 100644
--- a/www/manager6/node/NodeOptionsView.js
+++ b/www/manager6/node/NodeOptionsView.js
@@ -3,6 +3,8 @@ Ext.define('Proxmox.node.NodeOptionsView', {
     alias: ['widget.proxmoxNodeOptionsView'],
     mixins: ['Proxmox.Mixin.CBind'],
 
+    cwidth1: 250,
+
     cbindData: function(_initialconfig) {
 	let me = this;
 
@@ -64,5 +66,21 @@ Ext.define('Proxmox.node.NodeOptionsView', {
 		return value;
 	    },
 	},
+	{
+	    xtype: 'integer',
+	    name: 'ballooning-target',
+	    text: gettext('RAM usage target for ballooning'),
+	    minValue: 0,
+	    maxValue: 100,
+	    deleteEmpty: true,
+	    onlineHelp: 'qm_memory',
+	    renderer: function(value) {
+		if (value === undefined) {
+		    return gettext('Default (80%)');
+		}
+
+		return Ext.htmlEncode(`${value}%`);
+	    },
+	},
     ],
 });
-- 
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[pve-devel] [PATCH docs 4/4] pvenode: document ballooning-target node option

[Friedrich Weber]

Also adjust the ballooning documentation to mention and
cross-reference this node option.

Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
---
 pvenode.adoc | 13 +++++++++++++
 qm.adoc      | 13 ++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/pvenode.adoc b/pvenode.adoc
index 21a46a8..f3e99ce 100644
--- a/pvenode.adoc
+++ b/pvenode.adoc
@@ -192,6 +192,19 @@ pvenode migrateall pve2 --vms 100,101,102 --with-local-disks
 
 // TODO: explain node shutdown (stopall is used there) and maintenance options
 
+[[ballooning-target]]
+RAM Usage Target for Ballooning
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The target percentage for xref:qm_ballooning[automatic memory allocation]
+defaults to 80%. You can customize this target per node by setting the
+`ballooning-target` property. For example, to target 90% host memory usage
+instead:
+
+----
+pvenode config set --ballooning-target 90
+----
+
 ifdef::manvolnum[]
 include::pve-copyright.adoc[]
 endif::manvolnum[]
diff --git a/qm.adoc b/qm.adoc
index 4bb8f2c..07ec5cf 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -697,13 +697,15 @@ it (like for debugging purposes), simply uncheck *Ballooning Device* or set
 
 in the configuration.
 
+[[qm_ballooning]]
 .Automatic Memory Allocation
 
 // see autoballoon() in pvestatd.pm
-When setting the minimum memory lower than memory, {pve} will make sure that the
-minimum amount you specified is always available to the VM, and if RAM usage on
-the host is below 80%, will dynamically add memory to the guest up to the
-maximum memory specified.
+When setting the minimum memory lower than memory, {pve} will make sure that
+the minimum amount you specified is always available to the VM, and if RAM
+usage on the host is below a certain target percentage, will dynamically add
+memory to the guest up to the maximum memory specified. The target percentage
+defaults to 80% and can be configured xref:ballooning-target[in the node options].
 
 When the host is running low on RAM, the VM will then release some memory
 back to the host, swapping running processes if needed and starting the oom
@@ -715,7 +717,8 @@ footnote:[A good explanation of the inner workings of the balloon driver can be
 When multiple VMs use the autoallocate facility, it is possible to set a
 *Shares* coefficient which indicates the relative amount of the free host memory
 that each VM should take. Suppose for instance you have four VMs, three of them
-running an HTTP server and the last one is a database server. To cache more
+running an HTTP server and the last one is a database server.
+The host is configured to target 80% RAM usage. To cache more
 database blocks in the database server RAM, you would like to prioritize the
 database VM when spare RAM is available. For this you assign a Shares property
 of 3000 to the database VM, leaving the other VMs to the Shares default setting
-- 
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Re: [pve-devel] [PATCH manager/docs 0/4] fix #2413: make target for ballooning configurable

[Stoiko Ivanov]

Thanks for the patch!

comments inline:
On Wed, 12 Mar 2025 16:15:02 +0100
Friedrich Weber <f.weber@proxmox.com> wrote:

> Automatic memory allocation (ballooning) is implemented in pvestatd, which
> assigns memory to or reclaims memory from eligible VMs in order to reach a
> certain target memory usage on the host. The target is currently hardcoded at
> 80%. Users have reported [1] that this target is unnecessarily low on hosts
> with large amounts of RAM.
> 
> This patch series makes the ballooning target configurable. For this, it adds a
> new node config option `ballooning-target`. pvestatd then reads the target from
> that option.
> 
> Some potential discussion points:
> 
> - Is it OK to have this as a node option? I imagine some users may want to set
>   different targets on different nodes. But other users may want to set one
>   target for the whole cluster. Should we have a `ballooning-target` datacenter
>   option that can be overridden by a `ballooning-target` node option? This might
>   be overkill for such a simple option, though.
my initial thought would put this on the Datacenter-level (expecting most
nodes to be similarly specced - and thus have similar settings).
OTOH your approach gives the user more flexibility (if at the expense of
having to set that (via config-management or manually) for all nodes).

I think we could keep it on the node-level, and if there is demand for
this follow it up as you suggested:
node-setting > datacenter-setting > default(80%)

> 
> - Instead of a `ballooning-target` option, should we go for some general
>   `ballooning-settings` with a property string like `target=80`, in case we want
>   to make other values (such as `$maxchange`, which is currently hardcoded at 100
>   MiB) configurable in the future too?
we could cross that bridge when we get to it/when someone requests this
change (via versioned postinst renaming)? - at least I don't see the gain
- especially when it's in node.cfg.
and even if we have a datacenter.cfg-wide setting in a mixed-version
cluster while upgrading the config-parser would complain about an unknown
entry in a property-string as much as about an unknown setting IIRC?


> 
> - In a mixed-version cluster where node 1 has this patch series and node 2
>   doesn't yet, any attempt to change node 2's ballooning target from node 1's GUI
>   will error out with `ballooning-target: property is not defined in schema`.
>   This is not very nice, but not terrible either, as the error message is
>   relatively descriptive. Still, is there an easy way to avoid this (checking
>   client-side whether the option exists?)
I think the error-message is acceptable here (and nodes in a cluster
should run the same versions sooner rather than later anyways).

gave it a quick spin (by installing on my host, setting the target to 10%,
adding a `balloon` setting for a VM of mine and running `pvestatd start
--debug 1`, watching it inflate the balloon and the setting the target to
99%, watching it deflate it again).

For me this can be applied as-is:

Tested-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Reviewed-by: Stoiko Ivanov <s.ivanov@proxmox.com>

> 
> [1] https://bugzilla.proxmox.com/show_bug.cgi?id=2413
> 
> manager:
> 
> Friedrich Weber (3):
>   node: options: add config option for ballooning target
>   fix #2413: pvestatd: read ballooning RAM usage target from node config
>   ui: node options: allow editing the ballooning RAM usage target
> 
>  PVE/NodeConfig.pm                    |  8 ++++++++
>  PVE/Service/pvestatd.pm              | 10 +++++++---
>  www/manager6/node/NodeOptionsView.js | 18 ++++++++++++++++++
>  3 files changed, 33 insertions(+), 3 deletions(-)
> 
> 
> docs:
> 
> Friedrich Weber (1):
>   pvenode: document ballooning-target node option
> 
>  pvenode.adoc | 13 +++++++++++++
>  qm.adoc      | 13 ++++++++-----
>  2 files changed, 21 insertions(+), 5 deletions(-)
> 
> 
> Summary over all repositories:
>   5 files changed, 54 insertions(+), 8 deletions(-)
> 



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Re: [pve-devel] [PATCH manager/docs 0/4] fix #2413: make target for ballooning configurable

[Friedrich Weber]

Thanks for the review+test!

On 04/04/2025 14:47, Stoiko Ivanov wrote:
> Thanks for the patch!
> 
> comments inline:
> On Wed, 12 Mar 2025 16:15:02 +0100
> Friedrich Weber <f.weber@proxmox.com> wrote:
> 
>> Automatic memory allocation (ballooning) is implemented in pvestatd, which
>> assigns memory to or reclaims memory from eligible VMs in order to reach a
>> certain target memory usage on the host. The target is currently hardcoded at
>> 80%. Users have reported [1] that this target is unnecessarily low on hosts
>> with large amounts of RAM.
>>
>> This patch series makes the ballooning target configurable. For this, it adds a
>> new node config option `ballooning-target`. pvestatd then reads the target from
>> that option.
>>
>> Some potential discussion points:
>>
>> - Is it OK to have this as a node option? I imagine some users may want to set
>>   different targets on different nodes. But other users may want to set one
>>   target for the whole cluster. Should we have a `ballooning-target` datacenter
>>   option that can be overridden by a `ballooning-target` node option? This might
>>   be overkill for such a simple option, though.
> my initial thought would put this on the Datacenter-level (expecting most
> nodes to be similarly specced - and thus have similar settings).
> OTOH your approach gives the user more flexibility (if at the expense of
> having to set that (via config-management or manually) for all nodes).
> 
> I think we could keep it on the node-level, and if there is demand for
> this follow it up as you suggested:
> node-setting > datacenter-setting > default(80%)

Yeah, that sounds sensible.

> 
>>
>> - Instead of a `ballooning-target` option, should we go for some general
>>   `ballooning-settings` with a property string like `target=80`, in case we want
>>   to make other values (such as `$maxchange`, which is currently hardcoded at 100
>>   MiB) configurable in the future too?
> we could cross that bridge when we get to it/when someone requests this
> change (via versioned postinst renaming)? - at least I don't see the gain
> - especially when it's in node.cfg.
> and even if we have a datacenter.cfg-wide setting in a mixed-version
> cluster while upgrading the config-parser would complain about an unknown
> entry in a property-string as much as about an unknown setting IIRC?

True, though if we might want a general ballooning-settings option in
the future (like `ballooning-settings: target=80,step=100`), going for
`ballooning-settings` already now would spare us from the hassle of
renaming/deprecating ballooning-target -> ballooning-settings on
upgrade. I don't think it would help in the mixed-version scenario,
that's true.

>>
>> - In a mixed-version cluster where node 1 has this patch series and node 2
>>   doesn't yet, any attempt to change node 2's ballooning target from node 1's GUI
>>   will error out with `ballooning-target: property is not defined in schema`.
>>   This is not very nice, but not terrible either, as the error message is
>>   relatively descriptive. Still, is there an easy way to avoid this (checking
>>   client-side whether the option exists?)
> I think the error-message is acceptable here (and nodes in a cluster
> should run the same versions sooner rather than later anyways).
> 
> gave it a quick spin (by installing on my host, setting the target to 10%,
> adding a `balloon` setting for a VM of mine and running `pvestatd start
> --debug 1`, watching it inflate the balloon and the setting the target to
> 99%, watching it deflate it again).
> 
> For me this can be applied as-is:
> 
> Tested-by: Stoiko Ivanov <s.ivanov@proxmox.com>
> Reviewed-by: Stoiko Ivanov <s.ivanov@proxmox.com>
> 

Thanks!


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