Xen 3.0.4 - Ballooning

Xen 3.0.4 - Ballooning

[Sébastien RICCIO]

Hi,

Maybe it's a dumb question, but I'm actually trying to understand how 
the memory allocation works within Xen.

I try to give 128MB to a domU and see if it increases for example when I 
"nano" a 500mb file, but the process
just get killed when it reachs the 128MB memory limit.

How do I configure the guests so they can ask for more memory until a 
limit is reached ?

Thanks a lot for your help.

Best regards
-- 

Sébastien Riccio
SwissCenter / OpenBusiness SA
sr@openbusiness.com
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Re: Xen 3.0.4 - Ballooning

[Andrew D. Ball]

Not such a dumb question.  As far as I know, memory ballooning is only
done from the control partition (dom0) nowadays, explicitly.

It would be nice for something inside of a domU's kernel or userspace to
watch 
some metric and then ask nicely for more memory if needed.  Paravirtual
drivers
can do this for sure, but I haven't poked around enough to know which
available
ones do and how to trigger it.

Peace.
Andrew

On Mon, 2007-01-08 at 11:21 +0100, Sébastien RICCIO wrote:
> Hi,
> 
> Maybe it's a dumb question, but I'm actually trying to understand how 
> the memory allocation works within Xen.
> 
> I try to give 128MB to a domU and see if it increases for example when I 
> "nano" a 500mb file, but the process
> just get killed when it reachs the 128MB memory limit.
> 
> How do I configure the guests so they can ask for more memory until a 
> limit is reached ?
> 
> Thanks a lot for your help.
> 
> Best regards

Re: Xen 3.0.4 - Ballooning

[Sébastien RICCIO]

Hi Andrew,

Thank you a lot for your answer. I will try to play with this a little.

Best regards.


-- 
Sébastien Riccio
SwissCenter / OpenBusiness SA
sr@openbusiness.com



Andrew D. Ball a écrit :
> Not such a dumb question.  As far as I know, memory ballooning is only
> done from the control partition (dom0) nowadays, explicitly.
>
> It would be nice for something inside of a domU's kernel or userspace to
> watch 
> some metric and then ask nicely for more memory if needed.  Paravirtual
> drivers
> can do this for sure, but I haven't poked around enough to know which
> available
> ones do and how to trigger it.
>
> Peace.
> Andrew
>
> On Mon, 2007-01-08 at 11:21 +0100, Sébastien RICCIO wrote:
>   
>> Hi,
>>
>> Maybe it's a dumb question, but I'm actually trying to understand how 
>> the memory allocation works within Xen.
>>
>> I try to give 128MB to a domU and see if it increases for example when I 
>> "nano" a 500mb file, but the process
>> just get killed when it reachs the 128MB memory limit.
>>
>> How do I configure the guests so they can ask for more memory until a 
>> limit is reached ?
>>
>> Thanks a lot for your help.
>>
>> Best regards
>>     
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
>
>   

question about gmfn_to_mfn()

[tgh]

hi
 I read the code of balloon part,  I am  confused about  the meaning and 
function of " mfn = gmfn_to_mfn(d, gmfn);"
 what is gmfn  and  and what is mfn?  and" #define gmfn_to_mfn(_d, 
gpfn)  mfn_x(sh_gfn_to_mfn(_d, gpfn))"
it seems that  gmfn and gpfn  is the same  or  what is the trick in it ?

I am confused about it

could you help me
Thanks in advance

RE: question about gmfn_to_mfn()

[Guy Zana]

mfn = machine frame number, it is an index to a page in the real memory of the system.
gmfn = guest's machine frame number and it sometimes called gpfn or just pfn. 
Guests have a translation table between their own virtualized pseudo physical memory and the real machine memory -> this is exactly what gmfn_to_mfn does.
Pfn is a generic term that might be used in all kind of situations so you should understand from the context.

Guy. 

> -----Original Message-----
> From: xen-devel-bounces@lists.xensource.com 
> [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of tgh
> Sent: Friday, March 23, 2007 5:31 AM
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] question about gmfn_to_mfn()
> 
> hi
>  I read the code of balloon part,  I am  confused about  the 
> meaning and function of " mfn = gmfn_to_mfn(d, gmfn);"
>  what is gmfn  and  and what is mfn?  and" #define gmfn_to_mfn(_d,
> gpfn)  mfn_x(sh_gfn_to_mfn(_d, gpfn))"
> it seems that  gmfn and gpfn  is the same  or  what is the 
> trick in it ?
> 
> I am confused about it
> 
> could you help me
> Thanks in advance
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
> 

Re: question about gmfn_to_mfn()

[Keir Fraser]

GPFN is guest machine frame number. It equals GPFN for fully-translated
(e.g., HVM guests). It equals MFN for ordinary PV guests which maintain
their own p2m translation table.

 -- Keir


On 23/3/07 06:56, "Guy Zana" <guy@neocleus.com> wrote:

> mfn = machine frame number, it is an index to a page in the real memory of the
> system.
> gmfn = guest's machine frame number and it sometimes called gpfn or just pfn.
> Guests have a translation table between their own virtualized pseudo physical
> memory and the real machine memory -> this is exactly what gmfn_to_mfn does.
> Pfn is a generic term that might be used in all kind of situations so you
> should understand from the context.
> 
> Guy. 
> 
>> -----Original Message-----
>> From: xen-devel-bounces@lists.xensource.com
>> [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of tgh
>> Sent: Friday, March 23, 2007 5:31 AM
>> To: xen-devel@lists.xensource.com
>> Subject: [Xen-devel] question about gmfn_to_mfn()
>> 
>> hi
>>  I read the code of balloon part,  I am  confused about  the
>> meaning and function of " mfn = gmfn_to_mfn(d, gmfn);"
>>  what is gmfn  and  and what is mfn?  and" #define gmfn_to_mfn(_d,
>> gpfn)  mfn_x(sh_gfn_to_mfn(_d, gpfn))"
>> it seems that  gmfn and gpfn  is the same  or  what is the
>> trick in it ?
>> 
>> I am confused about it
>> 
>> could you help me
>> Thanks in advance
>> 
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: question about gmfn_to_mfn()

[tgh]

Thank you all for all replys

In the HVM ,xen maintain guestos p2m table ,while in the paravirt ,guest 
maintain its own p2m,is it right?

Then in the paravirt case, if a VM's memory maxsize is 512M,and it is 
allocated 256M by "xm mem-set ",and it maybe only use 128M for running 
its OS and application , then what does its v2p table(or it is v2m talbe 
,I am not for sure) and p2m table look like in the aspect of size? and 
what about guestOS's mem_map size,is it 512M or 256M or 128M or 
something else?

another confusion for me is how does guestOS maitain its p2m table 
(linux has the v2p table ,but not p2m table),and what about the working 
procession for these tables?

could you help me
Thanks in advance








Keir Fraser 写道:
> GPFN is guest machine frame number. It equals GPFN for fully-translated
> (e.g., HVM guests). It equals MFN for ordinary PV guests which maintain
> their own p2m translation table.
>
>  -- Keir
>
>
> On 23/3/07 06:56, "Guy Zana" <guy@neocleus.com> wrote:
>
>   
>> mfn = machine frame number, it is an index to a page in the real memory of the
>> system.
>> gmfn = guest's machine frame number and it sometimes called gpfn or just pfn.
>> Guests have a translation table between their own virtualized pseudo physical
>> memory and the real machine memory -> this is exactly what gmfn_to_mfn does.
>> Pfn is a generic term that might be used in all kind of situations so you
>> should understand from the context.
>>
>> Guy. 
>>
>>     
>>> -----Original Message-----
>>> From: xen-devel-bounces@lists.xensource.com
>>> [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of tgh
>>> Sent: Friday, March 23, 2007 5:31 AM
>>> To: xen-devel@lists.xensource.com
>>> Subject: [Xen-devel] question about gmfn_to_mfn()
>>>
>>> hi
>>>  I read the code of balloon part,  I am  confused about  the
>>> meaning and function of " mfn = gmfn_to_mfn(d, gmfn);"
>>>  what is gmfn  and  and what is mfn?  and" #define gmfn_to_mfn(_d,
>>> gpfn)  mfn_x(sh_gfn_to_mfn(_d, gpfn))"
>>> it seems that  gmfn and gpfn  is the same  or  what is the
>>> trick in it ?
>>>
>>> I am confused about it
>>>
>>> could you help me
>>> Thanks in advance
>>>
>>>
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@lists.xensource.com
>>> http://lists.xensource.com/xen-devel
>>>
>>>       
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>>     
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
>
>