Re: Re: [XenARM] Which ARM architecture is plannet to be supported.

[서상범 <sbuk.suh@xxxxxxxxxxx>]

Hi,

I presume that Xen ARM hypervisor has shown the best performance compared with 
other solutions as you mentioned.
Please find the benchmark information of my presentation, 
http://www.xen.org/files/xensummit_intel09/XenARMTalk.pdf
at the Xen Summit Asia 2009.
One of major performance issues was caused by TLB cache handling, as ARM v5 
core has got virtual cache.

Presumably, one of good applications ussing hypervisor is security enhancement 
of devices.
I  think that you can find other applications using Xen ARM from my Xen Summit 
Presentation below or also from an ACM MobiCom 09 paper.
FYI, the latest presentation when I gave August 2011 at Xen Summit North 
America may give an update about the status of Xen ARM in terms of ARM CPU 
support and OS support 
and evolution of Xen ARM in terms of architecture and performance also will be 
found at my presentations since Xen Summit at IBM in 2007.
On the other hand, Cortex A15 is mentioned as a future plan of the Xen ARM 
project. where Cortex A15 is based on ARM v7.

Regarding Xen x86, it can use para-virtualized Linux and non-virtualized OS as 
some Intel CPU already supports virtualization extension
such as sub-ring 0 to run hypervisor.

I have worked for hosting of Xen Summit Asia 2011 November 2 and 3 and if you 
are interested in more latest information from ARM and others, please attend 
the Summit as speakers from ARM, other leading companies as for hypervisor, CPU 
and cloud computing will give talks.

I hope this answers your questions.

Sang-bum

===============================================================
Sang-bum Suh, PhD
Vice President, S/W Platform Lab
S/W Platform Team, DMC Research Center
Samsung Electronics
email: sbuk.suh@xxxxxxxxxxx
===============================================================

------- Original Message -------
Sender : Jean-Christophe DUBOIS<jcd@xxxxxxxxxxxxxxx> 
Date   : 2011-09-27 06:56 (GMT+09:00)
Title  : Re: [XenARM] Which ARM architecture is plannet to be supported.

Hello Sang-burn,

Thanks for your answer. 

If I read you correctly, Xen on ARM for ARMv5 and ARMv6 does not seem good 
performance wise. Do you have some benchmarks on this topic (Linux bare metal 
compared to Linux on top of Xen)? Obviously the lack of virtualization 
features on these processors mandates the use of a para-virtualized low level 
API that may certainly have its drawbacks. 

Now excuse my ignorance but it seems other hypervisors out there (the L4 
familly for example) have acceptable performance hit when it comes to running 
Linux on ARM. In addition you may want to consider that for certain type of 
application the use of an hypervisor may not be driven only by performance 
reasons. Hypervisors are bringing other types of benefits/services.  An there 
are a lot of devices out there which are not ARMv7 based and that would be too 
bad to let them Xen-orphaned.

Beside Xen still supports generic x86 (32 bits) architecture which for the 
most part has no hardware support for virtualization and therefore also need 
to take the para-virtualization way with the same kind of performance hit I 
guess. Is it real worse on ARM?

As for cortex A15 it is "just" another ARMv7 processor with added 
virtualization features so it certainly make sense to add support for it after 
the CortexA8/A9 is done. But there will not be a lot of people out there able 
to help as the access to such hardware will be scarce at first.

Regards

JC

On Monday 26 September 2011 04:02:01 you wrote:
> Hi,
> 
> Xen ARM source code based on ARM v7 with multicore support has recently
> been changed so that CPU architecture independent code of x86 based Xen
> mainline will be shared I have a plan to support the future Cortex A15
> virtualization extension.
> 
> On the other hand, I have released Xen ARM hypervisor source code since
> 2008, which includes ARM v5, v6 and the para-virtualized ARM Linux kernel
> patch. These source code can be found at the Xen ARM wiki of Xen.org.
> 
> Considering performance issues in terms of CPU overhead, context switching
> overhead due to cache architecture and CPU architecture such as multicore
> support issues,
> I think that it is better for ARM v5 and v6 Xen ARM hypervisor source code
> to not be merged with the Xen mainline.
> 
> I suggest to use the archieved Xen ARM hypervisor for ARM v5 and v6 at the
> Xen ARM wiki.
> 
> Thank you,
> 
> Sang-bum
> 
> ===============================================================
> Sang-bum Suh, PhD
> Vice President, S/W Platform Lab
> S/W Platform Team, DMC Research Center
> Samsung Electronics
> email: sbuk.suh@xxxxxxxxxxx
> ===============================================================
> 
> ------- Original Message -------
> Sender : Jean-Christophe DUBOIS<jcd@xxxxxxxxxxxxxxx>
> Date   : 2011-09-24 05:29 (GMT+09:00)
> Title  : [XenARM] Which ARM architecture is plannet to be supported.
> 
> Hello,
> 
> Just out of curiosity is this project only planning on supporting the ARMv7
> architecture or are ARMv5 and v6 still part of the plan?
> 
> Thanks.
> 
> JC
> 
> _______________________________________________
> Xen-arm mailing list
> Xen-arm@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/mailman/listinfo/xen-arm

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