[ale] Memory and virtualization

Jim Kinney jim.kinney at gmail.com
Fri Jul 12 09:31:00 EDT 2013


The ballooning process works pretty well to share memory chunks across VMs.
I've used it in KVM. The chunks are all supposedly read-only with copy on
write the same as a thin allocation vm clone. So the caching works in your
favor.

Here's the kicker for running Linux vm on a Linux host: that caching also
works in your favor! For windows vm, not at all. But between windows vms it
does work.

What I have not seen is how to specify/change page size for
allocation/sharing. Is it always a fixed size? Can I get more efficiency
from a variable page size? I would think so. a host has glibc in ram as do
all VMs using glibc. That save one or more pointers for each vm if all of
glibc is a single page.


On Fri, Jul 12, 2013 at 9:07 AM, Ed Cashin <ecashin at noserose.net> wrote:

> One early technique (I saw a presentation on it at OSDI 2003, I think) for
> reclaiming memory from guests was memory ballooning.  You can Google for,
> e.g.,
>
>   vmware ballooning
>
> ... to learn more about it.  This blog post talks about some of the other
> techniques.
>
>
> http://blogs.vmware.com/virtualreality/2011/02/hypervisor-memory-management-done-right.html
>
> I have no idea, really, about Hyper-V, but these are the most obvious
> techniques to use, so I assume Hyper-V has to use the same kinds of
> techniques.  I'd be interested to hear about anything original they've come
> up with.
>
> On Fri, Jul 12, 2013 at 8:15 AM, Lightner, Jeff <JLightner at water.com>wrote:
>
>>   Given that Linux pre-caches/pre-buffers most memory presented to it
>> what impact if any does this have to memory allocation to a virtual guest
>> for the virtual platform itself?    That is to say if one has a mix of
>> Linux and Windows virtual machines on say Hyper-V or MWare does the memory
>> allocated to each Linux guest become totally unavailable to other guest
>> machines because of this pre-allocation or is oversubscription possible
>> without impacting the guest machines?****
>>
>> ** **
>>
>> P.S. Don’t tell me not to use Hyper-V unless you can provide
>> documentation it absolutely won’t work for RHELinux guests – I didn’t make
>> the choice and won’t be able to undo it    My question is NOT asking which
>> virtualization platform to use.****
>>
>> ** **
>>
>> ** **
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Athena®, Created for the Cause™
>>
>> Making a Difference in the Fight Against Breast Cancer
>>
>>
>>
>>
>>
>> *How and Why I Should Support Bottled Water!
>> *Do not relinquish your right to choose bottled water as a healthy
>> alternative to beverages that contain sugar, calories, etc. Your support of
>> bottled water will make a difference! Your signatures count! Go to
>> http://www.bottledwatermatters.org/luv-bottledwater-iframe/dswaters and
>> sign a petition to support your right to always choose bottled water. Help
>> fight federal and state issues, such as bottle deposits (or taxes) and
>> organizations that want to ban the sale of bottled water. Support community
>> curbside recycling programs. Support bottled water as a healthy way to
>> maintain proper hydration. Our goal is 50,000 signatures. Share this
>> petition with your friends and family today!
>>
>>
>>
>> ---------------------------------
>> CONFIDENTIALITY NOTICE: This e-mail may contain privileged or
>> confidential information and is for the sole use of the intended
>> recipient(s). If you are not the intended recipient, any disclosure,
>> copying, distribution, or use of the contents of this information is
>> prohibited and may be unlawful. If you have received this electronic
>> transmission in error, please reply immediately to the sender that you have
>> received the message in error, and delete it. Thank you.
>> ----------------------------------****
>>
>>
>>
>>
>> _______________________________________________
>> Ale mailing list
>> Ale at ale.org
>> http://mail.ale.org/mailman/listinfo/ale
>> See JOBS, ANNOUNCE and SCHOOLS lists at
>> http://mail.ale.org/mailman/listinfo
>>
>>
>
>
> --
>   Ed Cashin <ecashin at noserose.net>
>   http://noserose.net/e/
>   http://www.coraid.com/
>
> _______________________________________________
> Ale mailing list
> Ale at ale.org
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo
>
>


-- 
-- 
James P. Kinney III
*
*Every time you stop a school, you will have to build a jail. What you gain
at one end you lose at the other. It's like feeding a dog on his own tail.
It won't fatten the dog.
- Speech 11/23/1900 Mark Twain
*
http://electjimkinney.org
http://heretothereideas.blogspot.com/
*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ale.org/pipermail/ale/attachments/20130712/400105f9/attachment-0001.html>


More information about the Ale mailing list