Re: [Xen-devel] xen not able to use total physical memory present in the system (192GB)

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Tue, Sep 11, 2012 at 07:07:00PM +0530, ?????????????????? ???????????????  
wrote:
>    Hi
> 

Hello,

>    I am using xen-4.1.2 with fedora-16 (kernel version 3.1.0.7) as dom0 on
>    system having 192GB of RAM.
> 
>    When i booted system xm info shows (total _memory parameter as 192GB and
>    free_memory as 25MB) full memory but /proc/meminfo reports 132GB and xm
>    list also reports 192GB for dom0
> 

"xm list" reports 192 GB for dom0. So dom0 does have 192 GB allocated from Xen,
but the issue probably is that the Linux dom0 kernel isn't able to use all of 
it.

>    When I ran first VM with 32GB RAM, xm info started reporting memory for
>    dom0 around 132GB and 32GB for VM and cat /proc/meminfo on dom0 reported
>    around 100GB. I am able to boot 4 VMs with this setup but 5th VM fails to
>    boot with not enough memory.
> 
>    ultimately not able to use full system memory ? 60GB went missing from
>    memory.
> 

Why do you want to have all the memory in dom0 ? 

You should limit/dedicate dom0 to, say, 2 GB of memory, and leave the rest of 
the memory
free in the Xen hypervisor so it can be used for other VMs. 

See: http://wiki.xen.org/wiki/XenBestPractices

-- Pasi


>    
> [1]http://old-list-archives.xen.org/archives/html/xen-devel/2009-07/msg00521.html
> 
>    On this thread,
> 
>    Jan mentined
> 
>  "the hypervisor has been validated to work fine with 1Tb for much longer, it 
> was
>  really the Dom0 kernel that had issues when not passing a dom0_mem=
>  option".
> 
>  I am not using this option "dom0_mem". Is anybody faced any issue like this ?
> 
>  Thanks,
>  Aniket
> 
> References
> 
>    Visible links
>    1. 
> http://old-list-archives.xen.org/archives/html/xen-devel/2009-07/msg00521.html

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