Ballooning Linux vms not showing correct RAM amounts

[hellomotow]

Hello,

I am having issues with our Linux VMs not showing the correct amount of RAM allocated to them. Our system/VM has balloning + KSM enabled (apt install ksm-control-daemon). I have found only dmidecode to show the correct amount of RAM.

root@hostname:~# sudo dmidecode --type memory
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.8 present.


Handle 0x1000, DMI type 16, 23 bytes
Physical Memory Array
        Location: Other
        Use: System Memory
        Error Correction Type: Multi-bit ECC
        Maximum Capacity: 24 GB
        Error Information Handle: Not Provided
        Number Of Devices: 2


Handle 0x1100, DMI type 17, 40 bytes
Memory Device
        Array Handle: 0x1000
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: 16384 MB
        Form Factor: DIMM
        Set: None
        Locator: DIMM 0
        Bank Locator: Not Specified
        Type: RAM
        Type Detail: Other
        Speed: Unknown
        Manufacturer: QEMU
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: Not Specified
        Rank: Unknown
        Configured Clock Speed: Unknown
        Minimum Voltage: Unknown
        Maximum Voltage: Unknown
        Configured Voltage: Unknown


Handle 0x1101, DMI type 17, 40 bytes
Memory Device
        Array Handle: 0x1000
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: 8192 MB
        Form Factor: DIMM
        Set: None
        Locator: DIMM 1
        Bank Locator: Not Specified
        Type: RAM
        Type Detail: Other
        Speed: Unknown
        Manufacturer: QEMU
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: Not Specified
        Rank: Unknown
        Configured Clock Speed: Unknown
        Minimum Voltage: Unknown
        Maximum Voltage: Unknown
        Configured Voltage: Unknown

root@hostname:~# grep MemTotal /proc/meminfo
MemTotal:       10754692 kB

root@hostname:~# free -g
              total        used        free      shared  buff/cache   available
Mem:             10           0           8           0           1           9
Swap:             0           0           0

What can be done to make it show the correct amount while ballooning is still enabled? I have noticed that the less amount of RAM our node has free the the lower the amount will be sown for each VM even though we have RAM to spare still (it was even doing this when the total usage as <100GB)

 

[spirit]

The balloning feature, is lowering memory inside each guest vms, when your physical host reach around 80% memory.

you can set min memory = max memory, if you don't want memory decrease and still have ballon enabled. (it's the default when you create a vm)