[Xenomai] Virtualization with Xenomai

[Xenomai] Virtualization with Xenomai

[Asier Tamayo Arbide]

Hello all,

My embedded system has two boards running Linux: one runs the user
interface and the other one the critical real-time tasks. Both boards are
running Xenomai on an Atom N270 chipset.



Now, I am planning to compact my system in just one board and have two
options. The first one is to execute everything using Xenomai and the
second one is to port my user interface to Windows and to run both Windows
and Xenomai on top of a hypervisor. My e-mail regards this second option.



I would like to know if anyone has any experience with this. Is the
real-time response affected in any way when using a hypervisor? My current
kernel has been compiled using the ELinOS Embedded Linux distribution. Do I
have to patch it?



I am studying Xen, VmWare, KVM and Enea. Do you recommend any of them? The
board I’ll use in the new (compact) system will support virtualization
extensions (Intel VT).



Thank you for your help. Best regards,



Ata

Re: [Xenomai] Virtualization with Xenomai

[Nicolas Pinault]

Hello,

Le 29/08/2013 13:06, Asier Tamayo Arbide a écrit :
> Hello all,
>
> My embedded system has two boards running Linux: one runs the user
> interface and the other one the critical real-time tasks. Both boards are
> running Xenomai on an Atom N270 chipset.
>
>
>
> Now, I am planning to compact my system in just one board and have two
> options. The first one is to execute everything using Xenomai and the
> second one is to port my user interface to Windows and to run both Windows
> and Xenomai on top of a hypervisor. My e-mail regards this second option.
>
>
>
> I would like to know if anyone has any experience with this. Is the
> real-time response affected in any way when using a hypervisor? My current
> kernel has been compiled using the ELinOS Embedded Linux distribution. Do I
> have to patch it?
>
>
>
> I am studying Xen, VmWare, KVM and Enea. Do you recommend any of them? The
> board I’ll use in the new (compact) system will support virtualization
> extensions (Intel VT).
>
In Windows world, use RTX : 
http://www.intervalzero.com/products/rtx-rtx64/overview/

>
> Thank you for your help. Best regards,
>
>
>
> Ata
> _______________________________________________
> Xenomai mailing list
> Xenomai@xenomai.org
> http://www.xenomai.org/mailman/listinfo/xenomai
>

Re: [Xenomai] Virtualization with Xenomai

[Jan Kiszka]

On 2013-08-29 13:06, Asier Tamayo Arbide wrote:
> Hello all,
> 
> My embedded system has two boards running Linux: one runs the user
> interface and the other one the critical real-time tasks. Both boards are
> running Xenomai on an Atom N270 chipset.
> 
> Now, I am planning to compact my system in just one board and have two
> options. The first one is to execute everything using Xenomai and the
> second one is to port my user interface to Windows and to run both Windows
> and Xenomai on top of a hypervisor. My e-mail regards this second option.
> 

Third option may be even more interesting (provided you really want to
use Windows for the UI): Run Xenomai on the host and combine it with KVM
to host another OS. This works fine with latest ipipe for 3.8 when RT
tasks and the QEMU process (that uses KVM) are on separate CPUs, I just
heard of issues (couldn't reproduce yet) when they share a CPU.

> I would like to know if anyone has any experience with this. Is the
> real-time response affected in any way when using a hypervisor? My current
> kernel has been compiled using the ELinOS Embedded Linux distribution. Do I
> have to patch it?
> 

Virtualizing your RT workload won't make things faster, naturally.
Depending on the hypervisor architecture and hardware capabilities, it
may not be measurable. But I would refrain from such stacking unless
there is a real need (which I do not see for your setup).

> I am studying Xen, VmWare, KVM and Enea. Do you recommend any of them? The
> board I’ll use in the new (compact) system will support virtualization
> extensions (Intel VT).

See above.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

Re: [Xenomai] Virtualization with Xenomai

[Asier]

Jan, Nicolas,

Thank you for your help:

> Third option may be even more interesting (provided you really want to
> use Windows for the UI): Run Xenomai on the host and combine it with KVM
> to host another OS. This works fine with latest ipipe for 3.8 when RT
> tasks and the QEMU process (that uses KVM) are on separate CPUs, I just
> heard of issues (couldn't reproduce yet) when they share a CPU.
>
If I am not wrong, KVM runs on top of Linux, and then Windows on top of it.
Isn't it too much overhead? Isn't it better to use a Type 1 virtualization?
When you say separate CPUs, do you mean separate cores?

> Virtualizing your RT workload won't make things faster, naturally.
> Depending on the hypervisor architecture and hardware capabilities, it
> may not be measurable.
>
So, do you mean that, even though the system may be slower, the real-time
response will run smoothly?

> But I would refrain from such stacking unless there is a real need
> (which I do not see for your setup).
>
My plan for the mid term is to run the user interface (HMI) and the
real-time applications in one board. Meanwhile, I need to update my HMI and
I want to use a complete Linux distribution (one with a desktop manager)
with Xenomai. However, I may finally be forced to use Windows (3rd party
programs) and, when porting my system to one board, I would need some
virtualization tools.

Yesterday, I wrote another e-mail asking for opinions about a Linux
distribution with Xenomai, or about any experience with the Yocto project
and Xenomai. Has anyone got any information regarding this?


> In Windows world, use RTX :
http://www.intervalzero.com/products/rtx-rtx64/overview/
>
In fact, if I change from Xenomai Linux to Windows, first I will remove all
the real-time applications from that board and run them in the other one.
Anyway, it's an interesting link.

Thanks again,

Ata




2013/8/29 Jan Kiszka <jan.kiszka@siemens.com>

> On 2013-08-29 13:06, Asier Tamayo Arbide wrote:
> > Hello all,
> >
> > My embedded system has two boards running Linux: one runs the user
> > interface and the other one the critical real-time tasks. Both boards are
> > running Xenomai on an Atom N270 chipset.
> >
> > Now, I am planning to compact my system in just one board and have two
> > options. The first one is to execute everything using Xenomai and the
> > second one is to port my user interface to Windows and to run both
> Windows
> > and Xenomai on top of a hypervisor. My e-mail regards this second option.
> >
>
> Third option may be even more interesting (provided you really want to
> use Windows for the UI): Run Xenomai on the host and combine it with KVM
> to host another OS. This works fine with latest ipipe for 3.8 when RT
> tasks and the QEMU process (that uses KVM) are on separate CPUs, I just
> heard of issues (couldn't reproduce yet) when they share a CPU.
>
> > I would like to know if anyone has any experience with this. Is the
> > real-time response affected in any way when using a hypervisor? My
> current
> > kernel has been compiled using the ELinOS Embedded Linux distribution.
> Do I
> > have to patch it?
> >
>
> Virtualizing your RT workload won't make things faster, naturally.
> Depending on the hypervisor architecture and hardware capabilities, it
> may not be measurable. But I would refrain from such stacking unless
> there is a real need (which I do not see for your setup).
>
> > I am studying Xen, VmWare, KVM and Enea. Do you recommend any of them?
> The
> > board I’ll use in the new (compact) system will support virtualization
> > extensions (Intel VT).
>
> See above.
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SES-DE
> Corporate Competence Center Embedded Linux
>

Re: [Xenomai] Virtualization with Xenomai

[Nicolas Pinault]

Hi,
>> In Windows world, use RTX :
> http://www.intervalzero.com/products/rtx-rtx64/overview/
> In fact, if I change from Xenomai Linux to Windows, first I will remove all
> the real-time applications from that board and run them in the other one.
> Anyway, it's an interesting link.
>
Just for your knowledge : Rtx can be used with single-core or multi-core 
processors. In case of a multi-core processor, 1 or more core can be 
dedicated to real-time applications. You have to write a GUI application 
and a real-time application. Both communicate with each other through a 
dedicated API. Rtx is perfectly integrated in the dev tools (visual 
studio). On a Rtx enabled system, standard applications continue to run 
normally. The main drawback is the price.

Nicolas

Re: [Xenomai] Virtualization with Xenomai

[Jan Kiszka]

On 2013-08-30 09:11, Asier wrote:
> Jan, Nicolas,
> 
> Thank you for your help:
> 
>> Third option may be even more interesting (provided you really want to
>> use Windows for the UI): Run Xenomai on the host and combine it with KVM
>> to host another OS. This works fine with latest ipipe for 3.8 when RT
>> tasks and the QEMU process (that uses KVM) are on separate CPUs, I just
>> heard of issues (couldn't reproduce yet) when they share a CPU.
>>
> If I am not wrong, KVM runs on top of Linux, and then Windows on top of it.
> Isn't it too much overhead? Isn't it better to use a Type 1 virtualization?

Type 1 vs. type 2 is usually just marketing nonsense. You can do device
pass-through with KVM as well, thus removing most of the I/O
virtualization overhead, achieving near-native performance. Moreover, in
contrast to several other hypervisors, KVM can benefit a lot from its
architectural advantage to run hosted on Linux which reduced context
switches on x86.

> When you say separate CPUs, do you mean separate cores?

Usually, this means cores (on a single-socket system).

> 
>> Virtualizing your RT workload won't make things faster, naturally.
>> Depending on the hypervisor architecture and hardware capabilities, it
>> may not be measurable.
>>
> So, do you mean that, even though the system may be slower, the real-time
> response will run smoothly?

No general rule, depends on your hypervisor.

> 
>> But I would refrain from such stacking unless there is a real need
>> (which I do not see for your setup).
>>
> My plan for the mid term is to run the user interface (HMI) and the
> real-time applications in one board. Meanwhile, I need to update my HMI and
> I want to use a complete Linux distribution (one with a desktop manager)
> with Xenomai. However, I may finally be forced to use Windows (3rd party
> programs) and, when porting my system to one board, I would need some
> virtualization tools.
> 
> Yesterday, I wrote another e-mail asking for opinions about a Linux
> distribution with Xenomai, or about any experience with the Yocto project
> and Xenomai. Has anyone got any information regarding this?

There are debian packages for Xenomai, but it is trivial to build it for
any distro of your preference. Yocto-wise: ELDK, which should come with
Xenomai support IIRC, is based on yocto these days.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

Re: [Xenomai] Virtualization with Xenomai

[Asier]

Once again, thank you.Your last email was really helpful.

If I understand it correctly, for my system it is better to use the KVM
approach, that is, leave the Xenomai Linux running on top of the HW and the
Windows on KVM. Though this solution may have some overhead, the real-time
behaviour will be the same as before. Am I correct? Or it can't be said for
sure?

Regarding the Xenomai-aware Linux distributions, I'll have a look at the
debian packages for Xenomai. ELDK has no Intel support. I may consider
WindRiver Linux and Enea Linux, as well as using the Yocto tools themselves.

Best regards,

Asier







2013/8/30 Jan Kiszka <jan.kiszka@siemens.com>

> On 2013-08-30 09:11, Asier wrote:
> > Jan, Nicolas,
> >
> > Thank you for your help:
> >
> >> Third option may be even more interesting (provided you really want to
> >> use Windows for the UI): Run Xenomai on the host and combine it with KVM
> >> to host another OS. This works fine with latest ipipe for 3.8 when RT
> >> tasks and the QEMU process (that uses KVM) are on separate CPUs, I just
> >> heard of issues (couldn't reproduce yet) when they share a CPU.
> >>
> > If I am not wrong, KVM runs on top of Linux, and then Windows on top of
> it.
> > Isn't it too much overhead? Isn't it better to use a Type 1
> virtualization?
>
> Type 1 vs. type 2 is usually just marketing nonsense. You can do device
> pass-through with KVM as well, thus removing most of the I/O
> virtualization overhead, achieving near-native performance. Moreover, in
> contrast to several other hypervisors, KVM can benefit a lot from its
> architectural advantage to run hosted on Linux which reduced context
> switches on x86.
>
> > When you say separate CPUs, do you mean separate cores?
>
> Usually, this means cores (on a single-socket system).
>
> >
> >> Virtualizing your RT workload won't make things faster, naturally.
> >> Depending on the hypervisor architecture and hardware capabilities, it
> >> may not be measurable.
> >>
> > So, do you mean that, even though the system may be slower, the real-time
> > response will run smoothly?
>
> No general rule, depends on your hypervisor.
>
> >
> >> But I would refrain from such stacking unless there is a real need
> >> (which I do not see for your setup).
> >>
> > My plan for the mid term is to run the user interface (HMI) and the
> > real-time applications in one board. Meanwhile, I need to update my HMI
> and
> > I want to use a complete Linux distribution (one with a desktop manager)
> > with Xenomai. However, I may finally be forced to use Windows (3rd party
> > programs) and, when porting my system to one board, I would need some
> > virtualization tools.
> >
> > Yesterday, I wrote another e-mail asking for opinions about a Linux
> > distribution with Xenomai, or about any experience with the Yocto project
> > and Xenomai. Has anyone got any information regarding this?
>
> There are debian packages for Xenomai, but it is trivial to build it for
> any distro of your preference. Yocto-wise: ELDK, which should come with
> Xenomai support IIRC, is based on yocto these days.
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SES-DE
> Corporate Competence Center Embedded Linux
>

Re: [Xenomai] Virtualization with Xenomai

[Jan Kiszka]

On 2013-08-30 12:22, Asier wrote:
> Once again, thank you.Your last email was really helpful.
> 
> If I understand it correctly, for my system it is better to use the KVM
> approach, that is, leave the Xenomai Linux running on top of the HW and the
> Windows on KVM. Though this solution may have some overhead, the real-time
> behaviour will be the same as before. Am I correct?

Yes, you are.

> Or it can't be said for
> sure?
> 
> Regarding the Xenomai-aware Linux distributions, I'll have a look at the
> debian packages for Xenomai. ELDK has no Intel support. I may consider
> WindRiver Linux and Enea Linux, as well as using the Yocto tools themselves.

You might be able to "steal" a Xenomai recipe from ELDK.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

Re: [Xenomai] Virtualization with Xenomai

[Asier]

> You might be able to "steal" a Xenomai recipe from ELDK.
>

Thanks a lot ;-)

Asier


2013/8/30 Jan Kiszka <jan.kiszka@siemens.com>

> On 2013-08-30 12:22, Asier wrote:
> > Once again, thank you.Your last email was really helpful.
> >
> > If I understand it correctly, for my system it is better to use the KVM
> > approach, that is, leave the Xenomai Linux running on top of the HW and
> the
> > Windows on KVM. Though this solution may have some overhead, the
> real-time
> > behaviour will be the same as before. Am I correct?
>
> Yes, you are.
>
> > Or it can't be said for
> > sure?
> >
> > Regarding the Xenomai-aware Linux distributions, I'll have a look at the
> > debian packages for Xenomai. ELDK has no Intel support. I may consider
> > WindRiver Linux and Enea Linux, as well as using the Yocto tools
> themselves.
>
> You might be able to "steal" a Xenomai recipe from ELDK.
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SES-DE
> Corporate Competence Center Embedded Linux
>