xen not able to use total physical memory present in the system (192GB)

xen not able to use total physical memory present in the system (192GB)

[अनिकेत आगाशे]

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Hi

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

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.

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

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Re: xen not able to use total physical memory present in the system (192GB)

[Pasi Kärkkäinen]

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

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: xen not able to use total physical memory present in the system (192GB)

[Jan Beulich]

>>> On 11.09.12 at 15:37, अनिकेत आगाशे <agasheac@gmail.com> wrote:
> 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
> 
> 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.

Without you providing logs, we can only guess - like Pasi did - that
this may be a Dom0 kernel issue.

And - you aren't, by chance, running a 32-bit Dom0 kernel?

Jan

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Re: xen not able to use total physical memory present in the system (192GB)

[Konrad Rzeszutek Wilk]

On Tue, Sep 11, 2012 at 07:07:00PM +0530, अनिकेत आगाशे  wrote:
> Hi
> 
> I am using xen-4.1.2 with fedora-16 (kernel version 3.1.0.7) as dom0 on
> system having 192GB of RAM.


Can you check /boot/config* | grep XEN_MAX_DOMAIN


> 
> 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
> 
> 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.

There are also some bug-fixes for this that I've been posting that
I plan to integrate in v3.7.

Are you up for testing them out and to see if they work?
> 
> 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

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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