Re: [Xen-devel] xm mem-set for HVM Domain

[Andrew Lyon <andrew.lyon@xxxxxxxxx>]

On Sat, Sep 25, 2010 at 7:41 AM, cendhu <cendhu@xxxxxxxxx> wrote:
> HI,
>      I have an ubuntu 10.04 with xen kernel 2.6.32.11 as Dom0. xm mem-set
> does not seem to have any effect on the HVM domains.
> Xen Version : 4.0.1
> HVM : Ubuntu 10.04
> I have allocated 512MB to dom0 and 2048MB to HVM.
> $xm list
> Name                                        ID   Mem VCPUs      State
> Time(s)
> Domain-0                                     0   512     1     r-----
>  358.8
> lucid_hvm                                    1  2048     1     -b----
>  5.9
> The output of free command in the HVM
> $free -m
>              total       used       free     shared    buffers     cached
> Mem:          2012        153       1858          0         24         74
> -/+ buffers/cache:         55       1957
> Swap:          228          0        228
> Using xm mem-set, i tried to allocate 1024MB to the HVM
> $xm mem-set lucid_hvm 1024
> $xm list
> Name                                        ID   Mem VCPUs      State
> Time(s)
> Domain-0                                     0   512     1     r-----
>  363.1
> lucid_hvm                                    1  1024     1     -b----
>  7.2
>  xm list shows that only 1024MB of physical memory is allocated to the HVM.
> but, the output of free command in the HVM
> $ free -m
>              total       used       free     shared    buffers     cached
> Mem:          2012        154       1858          0         24         74
> -/+ buffers/cache:         55       1957
> Swap:          228          0        228
> No change in allocated memory. But, xm mem-set works perfectly with paraVM.
> I migrated HVM to another machine and checked the amount of data transferred
> which is 2048MB.
>
>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
>

I noticed the same thing a few days ago, I think that the mem-set
command should only work if there is a balloon driver running inside
the hvm domU which can "take away" the memory from the OS and return
it back to Xen, I don't understand why the command succeeds without a
balloon driver but your tests seem to show that it doesn't actually
work as migration moves the original amount of memory.

I will investigate this further tomorrow.

Andy

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel