[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(-)

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