* [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
@ 2012-04-03 6:56 Anisha Kaul
2012-04-03 7:17 ` Philippe Gerum
0 siblings, 1 reply; 6+ messages in thread
From: Anisha Kaul @ 2012-04-03 6:56 UTC (permalink / raw)
To: xenomai
Greetings,
>From "Life with Adeos":
http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Life-with-Adeos-rev-B.pdf
> Both the realtime nucleus and the Linux kernel should handle the case where a high priority thread is kept from running because a low priority one holds a contended resource > for a possibly unbounded amount of time. Xenomai provides this support, but only the PREEMPT_RT variant does so for the Linux kernel. For this reason, Xenomai keeps an
> eye and provides support for the current developments of PREEMPT_RT, albeit the mainline kernel still remains the system of reference for now.
I don't understand whether the above quote implies that it necessary
to apply the PREEMPT_RT patch (to Linux) when working with Xenomai on
Linux?
Please guide.
-Anisha
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
2012-04-03 6:56 [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it? Anisha Kaul
@ 2012-04-03 7:17 ` Philippe Gerum
2012-04-03 7:18 ` Philippe Gerum
0 siblings, 1 reply; 6+ messages in thread
From: Philippe Gerum @ 2012-04-03 7:17 UTC (permalink / raw)
To: xenomai
On 04/03/2012 08:56 AM, Anisha Kaul wrote:
> Greetings,
>
>> From "Life with Adeos":
> http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Life-with-Adeos-rev-B.pdf
>
>> Both the realtime nucleus and the Linux kernel should handle the case where a high priority thread is kept from running because a low priority one holds a contended resource> for a possibly unbounded amount of time. Xenomai provides this support, but only the PREEMPT_RT variant does so for the Linux kernel. For this reason, Xenomai keeps an
>> eye and provides support for the current developments of PREEMPT_RT, albeit the mainline kernel still remains the system of reference for now.
>
>
> I don't understand whether the above quote implies that it necessary
> to apply the PREEMPT_RT patch (to Linux) when working with Xenomai on
> Linux?
> Please guide.
>
No.
> -Anisha
>
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@domain.hid
> https://mail.gna.org/listinfo/xenomai-help
>
--
Philippe.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
2012-04-03 7:17 ` Philippe Gerum
@ 2012-04-03 7:18 ` Philippe Gerum
2012-04-03 7:37 ` Anisha Kaul
0 siblings, 1 reply; 6+ messages in thread
From: Philippe Gerum @ 2012-04-03 7:18 UTC (permalink / raw)
To: xenomai
On 04/03/2012 09:17 AM, Philippe Gerum wrote:
> On 04/03/2012 08:56 AM, Anisha Kaul wrote:
>> Greetings,
>>
>>> From "Life with Adeos":
>> http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Life-with-Adeos-rev-B.pdf
>>
>>
>>> Both the realtime nucleus and the Linux kernel should handle the
>>> case where a high priority thread is kept from running because a low
>>> priority one holds a contended resource> for a possibly unbounded
>>> amount of time. Xenomai provides this support, but only the
>>> PREEMPT_RT variant does so for the Linux kernel. For this reason,
>>> Xenomai keeps an
>>> eye and provides support for the current developments of PREEMPT_RT,
>>> albeit the mainline kernel still remains the system of reference for
>>> now.
>>
>>
>> I don't understand whether the above quote implies that it necessary
>> to apply the PREEMPT_RT patch (to Linux) when working with Xenomai on
>> Linux?
>> Please guide.
>>
>
> No.
I mean: this is not implied, and you don't need _RT (actually, to have
it, you would need a specific interrupt pipeline patch).
>
>> -Anisha
>>
>> _______________________________________________
>> Xenomai-help mailing list
>> Xenomai-help@domain.hid
>> https://mail.gna.org/listinfo/xenomai-help
>>
>
>
--
Philippe.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
2012-04-03 7:18 ` Philippe Gerum
@ 2012-04-03 7:37 ` Anisha Kaul
2012-04-03 7:42 ` Philippe Gerum
0 siblings, 1 reply; 6+ messages in thread
From: Anisha Kaul @ 2012-04-03 7:37 UTC (permalink / raw)
To: Philippe Gerum; +Cc: xenomai
On 3 April 2012 12:48, Philippe Gerum <rpm@xenomai.org> wrote:
>> No.
>
> I mean: this is not implied, and you don't need _RT (actually, to have it,
> you would need a specific interrupt pipeline patch).
Thanks for replying.
I read that this patch allows nearly all of the kernel to be
preempted, with the exception of a few very small regions of code
("raw_spinlock critical regions"), can you please point out a few
cases in which actually we "should" apply this patch?
Xenomai already gives a hard real time, so why would we need this
patch? Any hints please?
-Anisha
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
2012-04-03 7:37 ` Anisha Kaul
@ 2012-04-03 7:42 ` Philippe Gerum
2012-04-03 8:48 ` Anisha Kaul
0 siblings, 1 reply; 6+ messages in thread
From: Philippe Gerum @ 2012-04-03 7:42 UTC (permalink / raw)
To: Anisha Kaul; +Cc: xenomai
On 04/03/2012 09:37 AM, Anisha Kaul wrote:
> On 3 April 2012 12:48, Philippe Gerum<rpm@xenomai.org> wrote:
>>> No.
>>
>> I mean: this is not implied, and you don't need _RT (actually, to have it,
>> you would need a specific interrupt pipeline patch).
>
> Thanks for replying.
>
> I read that this patch allows nearly all of the kernel to be
> preempted, with the exception of a few very small regions of code
> ("raw_spinlock critical regions"), can you please point out a few
> cases in which actually we "should" apply this patch?
>
> Xenomai already gives a hard real time, so why would we need this
> patch? Any hints please?
>
>
This is a different approach to a same problem:
- _RT attempts to make the whole regular kernel real-time aware.
- Xenomai 2.x provides a co-kernel for exclusively handling real-time
processing.
There are pros and cons in the two approaches, this is basically why
Xenomai 3 will allow both.
> -Anisha
>
--
Philippe.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it?
2012-04-03 7:42 ` Philippe Gerum
@ 2012-04-03 8:48 ` Anisha Kaul
0 siblings, 0 replies; 6+ messages in thread
From: Anisha Kaul @ 2012-04-03 8:48 UTC (permalink / raw)
To: Philippe Gerum; +Cc: xenomai
On 3 April 2012 13:12, Philippe Gerum <rpm@xenomai.org> wrote:
> This is a different approach to a same problem:
> - _RT attempts to make the whole regular kernel real-time aware.
> - Xenomai 2.x provides a co-kernel for exclusively handling real-time
> processing.
>
> There are pros and cons in the two approaches, this is basically why Xenomai
> 3 will allow both.
>
Thanks, that was enlightening. Will read more on this.
-Anisha
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-04-03 8:48 UTC | newest]
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-- links below jump to the message on this page --
2012-04-03 6:56 [Xenomai-help] Is it compulsory to apply the PREEMPT_RT patch (to Linux) when running Xenomai on the top of it? Anisha Kaul
2012-04-03 7:17 ` Philippe Gerum
2012-04-03 7:18 ` Philippe Gerum
2012-04-03 7:37 ` Anisha Kaul
2012-04-03 7:42 ` Philippe Gerum
2012-04-03 8:48 ` Anisha Kaul
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