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14.13.7. Configuring Memory Allocation

To modify a guest virtual machine's memory allocation with virsh:
# virsh setmem {domain-id or domain-name} count
# virsh setmem vr-rhel6u1-x86_64-kvm --kilobytes 1025000
You must specify the count in kilobytes. The new count value cannot exceed the amount you specified when you created the guest virtual machine. Values lower than 64 MB are unlikely to work with most guest virtual machine operating systems. A higher maximum memory value does not affect active guest virtual machines. If the new value is lower than the available memory, it will shrink possibly causing the guest virtual machine to crash.
This command has the following options:
  • [--domain] <string> domain name, id or uuid
  • [--size] <number> new memory size, as scaled integer (default KiB)
    Valid memory units include:
    • b or bytes for bytes
    • KB for kilobytes (103 or blocks of 1,000 bytes)
    • k or KiB for kibibytes (210 or blocks of 1024 bytes)
    • MB for megabytes (106 or blocks of 1,000,000 bytes)
    • M or MiB for mebibytes (220 or blocks of 1,048,576 bytes)
    • GB for gigabytes (109 or blocks of 1,000,000,000 bytes)
    • G or GiB for gibibytes (230 or blocks of 1,073,741,824 bytes)
    • TB for terabytes (1012 or blocks of 1,000,000,000,000 bytes)
    • T or TiB for tebibytes (240 or blocks of 1,099,511,627,776 bytes)
    Note that all values will be rounded up to the nearest kibibyte by libvirt, and may be further rounded to the granularity supported by the hypervisor. Some hypervisors also enforce a minimum, such as 4000KiB (or 4000 x 210 or 4,096,000 bytes). The units for this value are determined by the optional attribute memory unit, which defaults to the kibibytes (KiB) as a unit of measure where the value given is multiplied by 210 or blocks of 1024 bytes.
  • --config takes affect next boot
  • --live controls the memory of the running domain
  • --current controls the memory on the current domain