When using PCI(e) passthrough, setting a minimum amount of memory does not have any effect, which may be surprising to users [0]. Add a note to the PCI(e) passthrough section, and reference it in the ballooning section.
[0] https://forum.proxmox.com/threads/134202/ Signed-off-by: Friedrich Weber <f.we...@proxmox.com> --- qm-pci-passthrough.adoc | 10 ++++++++++ qm.adoc | 5 +++++ 2 files changed, 15 insertions(+) diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc index 1f68721..406156d 100644 --- a/qm-pci-passthrough.adoc +++ b/qm-pci-passthrough.adoc @@ -20,6 +20,16 @@ PCI speeds. Passing through devices as PCIe just sets a flag for the guest to tell it that the device is a PCIe device instead of a "really fast legacy PCI device". Some guest applications benefit from this. +xref:qm_ballooning[Automatic memory allocation (ballooning)] is not possible +when using PCI(e) passthrough. As the PCI device may use DMA (Direct Memory +Access), QEMU needs to map the complete guest memory on VM startup. Hence, the +QEMU process will use at least the (maximum) configured amount of VM memory and +setting a minimum amount does not have any effect. When using PCI(e) +passthrough, it is recommended to set memory and minimum memory to the same +amount and keep the balloning device enabled. However, keep in mind that the +memory consumption reported in the GUI for the VM may be much lower than the +memory consumption of the QEMU process. + General Requirements ~~~~~~~~~~~~~~~~~~~~ diff --git a/qm.adoc b/qm.adoc index b7938d7..cbc5e0d 100644 --- a/qm.adoc +++ b/qm.adoc @@ -623,6 +623,7 @@ it (like for debugging purposes), simply uncheck *Ballooning Device* or set in the configuration. +[[qm_ballooning]] .Automatic Memory Allocation // see autoballoon() in pvestatd.pm @@ -659,6 +660,10 @@ systems. When allocating RAM to your VMs, a good rule of thumb is always to leave 1GB of RAM available to the host. +When using PCI(e) passthrough, setting a minimum amount of memory does not have +any effect, see the section on xref:qm_pci_passthrough[PCI(e) passthrough] for +more details. + [[qm_network_device]] Network Device -- 2.39.2 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
