2:05 p.m.
----- Original Message -----
From: "Sander Grendelman" <sander(a)grendelman.com>
To: "Michal Skrivanek" <michal.skrivanek(a)redhat.com>
Cc: users(a)ovirt.org
Sent: Friday, December 13, 2013 8:52:42 AM
Subject: Re: [Users] hot add ram to a vm
On Fri, Dec 13, 2013 at 1:42 PM, Michal Skrivanek
<michal.skrivanek(a)redhat.com> wrote:
> Too bad QEMU doesn't support it. So it's still a long way.
qemu/libvirt "kind of" supports it (at least in F19).
In virt-manager you can define "current" and "maximum" memory
allocation.
The VM only sees the current allocation and you can hot add memory up
to the maximum allocation.
It isn't really hot-plug.
This allows you to statically set the physical ram but then use the balloon device to
"borrow" some ram from the guest.
If max memory was 4gb and we set current memory to 2gb the VM would still see 4gb of
physical memory but the balloon driver would be taking up 2gb of memory in the guest, this
memory would be returned to the host for other VMs to use.
Example from the xml definition:
<memory unit='KiB'>3145728</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
After booting:
[root@grkvm201 ~]# uname -a
Linux grkvm201.plusine.intern 2.6.32-358.23.2.el6.x86_64 #1 SMP Wed
Oct 16 18:37:12 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
[root@grkvm201 ~]# free -lm
total used free shared buffers
cached
Mem: 837 296 540 0 8
84
Low: 837 296 540
High: 0 0 0
-/+ buffers/cache: 203 634
Swap: 511 0 511
[root@grkvm201 ~]#
memory increased to 2GB through virt-manager:
[root@grkvm201 ~]# free -lm
total used free shared buffers
cached
Mem: 1861 295 1565 0 8
84
Low: 1861 295 1565
High: 0 0 0
-/+ buffers/cache: 202 1659
Swap: 511 0 511
[root@grkvm201 ~]# cat /proc/meminfo
MemTotal: 1906176 kB
MemFree: 1603456 kB
Buffers: 9140 kB
Cached: 86860 kB
SwapCached: 0 kB
Active: 92564 kB
Inactive: 68064 kB
Active(anon): 68692 kB
Inactive(anon): 12 kB
Active(file): 23872 kB
Inactive(file): 68052 kB
Unevictable: 21600 kB
Mlocked: 11380 kB
SwapTotal: 524280 kB
SwapFree: 524280 kB
Dirty: 12 kB
Writeback: 0 kB
AnonPages: 86232 kB
Mapped: 20436 kB
Shmem: 288 kB
Slab: 75132 kB
SReclaimable: 14576 kB
SUnreclaim: 60556 kB
KernelStack: 1464 kB
PageTables: 4224 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 1477368 kB
Committed_AS: 547624 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 20040 kB
VmallocChunk: 34359688500 kB
HardwareCorrupted: 0 kB
AnonHugePages: 18432 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Memory decreased to 1,5GB through virt-manager:
[root@grkvm201 ~]# free -lm
total used free shared buffers
cached
Mem: 1349 295 1054 0 8
84
Low: 1349 295 1054
High: 0 0 0
-/+ buffers/cache: 201 1147
Swap: 511 0 511
[root@grkvm201 ~]#
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