FAQ for realtime support in Linux Kernel

FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Hello all,

I new in linux realtime mailing list. I have some doubts in my mind.
So I am looking for some FAQ for realtime support.

If any FAQ is available, please let me know.

I came up with list of questions and try to make FAQ for realtime
support. If some one interested to make FAQ please let me know.

I need your help and guidance to make this FAQ.

Please send some links, data and reviews which will be useful for this FAQ.

Thanks you,

Jaswinder Singh.

Question Index
----------------------
1. What is realtime support

2. How realtime works

3. What is the procedure to add realtime support

4. Download latest realtime patches

5. Realtime mailing list and archives

6. If I have some doubts or problems regarding realtime, do I need to
send mail in realtime mailing list or linux kernel mailing list or
both

7. Maintainers of realtime kernel patch

8. How to enable/disable realtime support

9. Change realtime support run time or statically

10. Required parameters for configuring realtime kernel

11. Optional parameters for configuring realtime kernel, but they
effect realtime performance

12. Which Architecture are supporting realtime and who is maintainer

13. What effects by realtime support and how much and samples to test
it and who maintains these samples

a. scheduling, task switching time

b. Interrupt latency

c. Interprocess communication

d. Filesystem

e. Device drivers

f. Network

g. X-Windows


14. List of realtime APIs

15. How to write realtime applications

16. Which programming languages are suitable for writing realtime applications

17. Keep following things in mind while writing realtime applications

18. Do I need to recompile my applications to get realtime performance

19. What is the procedure to support realtime in new architecture

20. Where can I post my realtime patches

Re: FAQ for realtime support in Linux Kernel

[Dirk Behme]

Jaswinder Singh wrote:
> I need your help and guidance to make this FAQ.
> 
> Please send some links, data and reviews which will be useful for this FAQ.

Did you read stuff and links on

http://rt.wiki.kernel.org/index.php/Main_Page

?

I think at least some of your questions below should be answered there.

If anything is missing, feel free to add it. And, if you like, I would 
propose to create a new FAQ page in above wiki and collect your 
answers there.

Best regards

Dirk


> Thanks you,
> 
> Jaswinder Singh.
> 
> Question Index
> ----------------------
> 1. What is realtime support
> 
> 2. How realtime works
> 
> 3. What is the procedure to add realtime support
> 
> 4. Download latest realtime patches
> 
> 5. Realtime mailing list and archives
> 
> 6. If I have some doubts or problems regarding realtime, do I need to
> send mail in realtime mailing list or linux kernel mailing list or
> both
> 
> 7. Maintainers of realtime kernel patch
> 
> 8. How to enable/disable realtime support
> 
> 9. Change realtime support run time or statically
> 
> 10. Required parameters for configuring realtime kernel
> 
> 11. Optional parameters for configuring realtime kernel, but they
> effect realtime performance
> 
> 12. Which Architecture are supporting realtime and who is maintainer
> 
> 13. What effects by realtime support and how much and samples to test
> it and who maintains these samples
> 
> a. scheduling, task switching time
> 
> b. Interrupt latency
> 
> c. Interprocess communication
> 
> d. Filesystem
> 
> e. Device drivers
> 
> f. Network
> 
> g. X-Windows
> 
> 
> 14. List of realtime APIs
> 
> 15. How to write realtime applications
> 
> 16. Which programming languages are suitable for writing realtime applications
> 
> 17. Keep following things in mind while writing realtime applications
> 
> 18. Do I need to recompile my applications to get realtime performance
> 
> 19. What is the procedure to support realtime in new architecture
> 
> 20. Where can I post my realtime patches
> -
> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

hello Dirk,

On 9/29/07, Dirk Behme <dirk.behme@googlemail.com> wrote:
> Jaswinder Singh wrote:
> > I need your help and guidance to make this FAQ.
> >
> > Please send some links, data and reviews which will be useful for this FAQ.
>
> Did you read stuff and links on
>
> http://rt.wiki.kernel.org/index.php/Main_Page
>
> ?

Yes.

>
> I think at least some of your questions below should be answered there.
>

Yes, some of the questions are already answered, but it will be great
if all these questions are under one FAQ, and FAQ answers will be to
the point and more details are available on Main page as you
referenced.

> If anything is missing, feel free to add it. And, if you like, I would
> propose to create a new FAQ page in above wiki and collect your
> answers there.
>

Sure Dirk please go ahead and take all these questions and setup FAQ.

If you have any doubts regarding any question, please let me know, I
will elaborate it.

And I will post few more questions later on.

Thank you,

Jaswinder Singh.

> Best regards
>
> Dirk
>
>
> > Thanks you,
> >
> > Jaswinder Singh.
> >
> > Question Index
> > ----------------------
> > 1. What is realtime support
> >
> > 2. How realtime works
> >
> > 3. What is the procedure to add realtime support
> >
> > 4. Download latest realtime patches
> >
> > 5. Realtime mailing list and archives
> >
> > 6. If I have some doubts or problems regarding realtime, do I need to
> > send mail in realtime mailing list or linux kernel mailing list or
> > both
> >
> > 7. Maintainers of realtime kernel patch
> >
> > 8. How to enable/disable realtime support
> >
> > 9. Change realtime support run time or statically
> >
> > 10. Required parameters for configuring realtime kernel
> >
> > 11. Optional parameters for configuring realtime kernel, but they
> > effect realtime performance
> >
> > 12. Which Architecture are supporting realtime and who is maintainer
> >
> > 13. What effects by realtime support and how much and samples to test
> > it and who maintains these samples
> >
> > a. scheduling, task switching time
> >
> > b. Interrupt latency
> >
> > c. Interprocess communication
> >
> > d. Filesystem
> >
> > e. Device drivers
> >
> > f. Network
> >
> > g. X-Windows
> >
> >
> > 14. List of realtime APIs
> >
> > 15. How to write realtime applications
> >
> > 16. Which programming languages are suitable for writing realtime applications
> >
> > 17. Keep following things in mind while writing realtime applications
> >
> > 18. Do I need to recompile my applications to get realtime performance
> >
> > 19. What is the procedure to support realtime in new architecture
> >
> > 20. Where can I post my realtime patches
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>
>

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

hello all,

I made sections in FAQ to make it more readable.

Thank you,

Jaswinder Singh.

FAQ for realtime support in Linux Kernel
---------------------------------------
Question Index
1. Realtime Support questions
2. Architecture questions
3. Mailing list questions
4. Realtime Patches questions
5. Configuring/compiling questions
6. Realtime samples/Performance questions
7. Realtime Applications questions
8. Maintainers  questions

Section 1 - Realtime Support questions

1. What is realtime support
2. How realtime works

Section 2 - Architecture questions

1. Which Architecture are supporting realtime and who is maintainer
2. What is the procedure to support realtime in new architecture

Section 3 - Mailing list questions

1. realtime mailing list and archives
2. If I have some doubts or problems regarding realtime, do I need to
send mail in realtime mailing list or linux kernel mailing list or
both

Section 4 - Realtime Patches questions

1. What is the procedure to add realtime support
2. Why I need to download realtime patches, If realtime support is in
Linux kernel
3. Download latest realtime patches
4. Where can I post my realtime patches

Section 5 - Configuring/compiling questions

1. How to enable/disable realtime support
2. Change realtime support run time or statically
3. Required parameters for configuring realtime kernel
4. Optional parameters for configuring realtime kernel, but they
effect realtime performance

Section 6 - Realtime samples/Performance questions

1. What effects by realtime support and how much and samples to test
it and who maintains these samples
a. scheduling, task switching time
b. Interrupt latency
c. Interprocess communication
d. Filesystem
e. Device drivers
f. Network
g. X-Windows

Section 7 - Realtime Applications questions

1. List of realtime APIs
2. How to write realtime applications
3. Which programming languages are suitable for writing realtime applications
4. Keep following things in mind while writing realtime applications
5. Do I need to recompile my applications to get realtime performance

Section 8 - Maintainers questions

1. Maintainers of realtime kernel patch


On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> Hello all,
>
> I new in linux realtime mailing list. I have some doubts in my mind.
> So I am looking for some FAQ for realtime support.
>
> If any FAQ is available, please let me know.
>
> I came up with list of questions and try to make FAQ for realtime
> support. If some one interested to make FAQ please let me know.
>
> I need your help and guidance to make this FAQ.
>
> Please send some links, data and reviews which will be useful for this FAQ.
>
> Thanks you,
>
> Jaswinder Singh.
>

Re: FAQ for realtime support in Linux Kernel

[Esben Nielsen]

On Sat, 29 Sep 2007, Jaswinder Singh wrote:

> hello all,
>
> I made sections in FAQ to make it more readable.
>
> Thank you,
>
> Jaswinder Singh.
>

I am not quite up to date with wiki-sites work. Can you send a direct 
link, please?

Esben

> FAQ for realtime support in Linux Kernel
> ---------------------------------------
> Question Index
> 1. Realtime Support questions
> 2. Architecture questions
> 3. Mailing list questions
> 4. Realtime Patches questions
> 5. Configuring/compiling questions
> 6. Realtime samples/Performance questions
> 7. Realtime Applications questions
> 8. Maintainers  questions
>
> Section 1 - Realtime Support questions
>
> 1. What is realtime support
> 2. How realtime works
>
> Section 2 - Architecture questions
>
> 1. Which Architecture are supporting realtime and who is maintainer
> 2. What is the procedure to support realtime in new architecture
>
> Section 3 - Mailing list questions
>
> 1. realtime mailing list and archives
> 2. If I have some doubts or problems regarding realtime, do I need to
> send mail in realtime mailing list or linux kernel mailing list or
> both
>
> Section 4 - Realtime Patches questions
>
> 1. What is the procedure to add realtime support
> 2. Why I need to download realtime patches, If realtime support is in
> Linux kernel
> 3. Download latest realtime patches
> 4. Where can I post my realtime patches
>
> Section 5 - Configuring/compiling questions
>
> 1. How to enable/disable realtime support
> 2. Change realtime support run time or statically
> 3. Required parameters for configuring realtime kernel
> 4. Optional parameters for configuring realtime kernel, but they
> effect realtime performance
>
> Section 6 - Realtime samples/Performance questions
>
> 1. What effects by realtime support and how much and samples to test
> it and who maintains these samples
> a. scheduling, task switching time
> b. Interrupt latency
> c. Interprocess communication
> d. Filesystem
> e. Device drivers
> f. Network
> g. X-Windows
>
> Section 7 - Realtime Applications questions
>
> 1. List of realtime APIs
> 2. How to write realtime applications
> 3. Which programming languages are suitable for writing realtime applications
> 4. Keep following things in mind while writing realtime applications
> 5. Do I need to recompile my applications to get realtime performance
>
> Section 8 - Maintainers questions
>
> 1. Maintainers of realtime kernel patch
>
>
> On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
>> Hello all,
>>
>> I new in linux realtime mailing list. I have some doubts in my mind.
>> So I am looking for some FAQ for realtime support.
>>
>> If any FAQ is available, please let me know.
>>
>> I came up with list of questions and try to make FAQ for realtime
>> support. If some one interested to make FAQ please let me know.
>>
>> I need your help and guidance to make this FAQ.
>>
>> Please send some links, data and reviews which will be useful for this FAQ.
>>
>> Thanks you,
>>
>> Jaswinder Singh.
>>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Hello all,

Please give contribution with open heart and give answers to max
questions as possible and give your reviews :


FAQ for realtime support in Linux Kernel
---------------------------------------
Question Index
1. Realtime Support questions
2. Architecture questions
3. Mailing list questions
4. Realtime Patches questions
5. Configuring/compiling questions
6. Realtime samples/Performance questions
7. Realtime Applications questions
8. Maintainers  questions

Section 1 - Realtime Support questions

Q1 What is realtime support
A1

Q2 How realtime works
A2 The RT-Preempt patch converts Linux into a fully preemptible
kernel. The magic is done with:

* Making in-kernel locking-primitives (using spinlocks) preemptible
though reimplementation with rtmutexes:
* Critical sections protected by i.e. spinlock_t and rwlock_t are now
preemptible. The creation of non-preemptible sections (in kernel) is
still possible with raw_spinlock_t (same APIs like spinlock_t)
* Implementing priority inheritance for in-kernel spinlocks and
semaphores. For more information on priority inversion and priority
inheritance please consult Introduction to Priority Inversion
* Converting interrupt handlers into preemptible kernel threads: The
RT-Preempt patch treats soft interrupt handlers in kernel thread
context, which is represented by a task_struct like a common userspace
process. However it is also possible to register an IRQ in kernel
context.
* Converting the old Linux timer API into separate infrastructures for
high resolution kernel timers plus one for timeouts, leading to
userspace POSIX timers with high resolution.

Q3 What is the procedure to add realtime support
A3 Download latest realtime preemption patch from
http://www.kernel.org/pub/linux/kernel/projects/rt/ then related get
vanilla kernel from http://kernel.org then patch , configure and
compile

Section 2 - Architecture questions

Q1 Which Architecture are supporting realtime and who is maintainer
A1

Q2 What is the procedure to support realtime in new architecture
A2

Section 3 - Mailing list questions

Q1 realtime mailing list and archives
A1 http://www.mail-archive.com/linux-rt-users@vger.kernel.org/

Q2 If I have some doubts or problems regarding realtime, do I need to
send mail in realtime mailing list or linux kernel mailing list or
both
A2

Section 4 - Realtime Patches questions

Q1 Why I need to download realtime patches, If realtime support is in
Linux kernel
A1

Q2 Download latest realtime patches
A2 http://www.kernel.org/pub/linux/kernel/projects/rt/

Q3 Where can I post my realtime patches
A3 Please send patches for the CONFIG_PREEMPT_RT Patch Set to LKML and
put Ingo Molnar and Thomas Gleixner on CC.

Please do not send clocksource and clockevents related patches against
the -rt patch. Make sure they apply against the latest -hrt-dyntick
patch. -hrt-dyntick might be a bit ahead of -rt at times, but the -rt
patch pulls -hrt-dyntick on a regular base.


Section 5 - Configuring/compiling questions

Q1 How to enable/disable realtime support
A1

Q2 Change realtime support run time or statically
A2

Q3 Required parameters for configuring realtime kernel
A3

Q4 Optional parameters for configuring realtime kernel, but they
effect realtime performance
A4

Section 6 - Realtime samples/Performance questions

Q1 What effects by realtime support and how much and samples to test
it and who maintains these samples
a. scheduling, task switching time
b. Interrupt latency
c. Interprocess communication
d. Filesystem
e. Device drivers
f. Network
g. X-Windows

Section 7 - Realtime Applications questions

Q1 List of realtime APIs
A1

Q2 How to write realtime applications
A2

Q3 Which programming languages are suitable for writing realtime applications
A3

Q4 Keep following things in mind while writing realtime applications
A4 Taking care of the following during the initial startup phase:
* Call directly from the main() entry the mlockall() call.
* Create all threads at startup time of the application, and touch
each page of the entire stack of each thread. Never start threads
dynamically during RT show time, this will ruin RT behavior.
* Never use system calls that are known to generate pagefaults, such
as fopen(). (Opening of files does the mmap() system call, which
generates a page-fault).
* Do not use 'compile time static arrays' without initializing them
directly after startup, before RT show time.


Q5 Do I need to recompile my applications to get realtime performance
A5

Section 8 - Maintainers questions

Q1 Maintainers of realtime kernel patch
A1

On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> hello all,
>
> I made sections in FAQ to make it more readable.
>
> Thank you,
>
> Jaswinder Singh.
>

Re: FAQ for realtime support in Linux Kernel

[Luis Claudio R. Goncalves]

Jaswinder,

On Sat, Sep 29, 2007 at 06:21:38PM +0530, Jaswinder Singh wrote:
| Hello all,
| 
| Please give contribution with open heart and give answers to max
| questions as possible and give your reviews :

I believe people were talking about you creating a FAQ entry in the RT Wiki
page, at http://rt.wiki.kernel.org/index.php/Main_Page.

| FAQ for realtime support in Linux Kernel
| ---------------------------------------
| Question Index
| 1. Realtime Support questions
| 2. Architecture questions
| 3. Mailing list questions
| 4. Realtime Patches questions
| 5. Configuring/compiling questions
| 6. Realtime samples/Performance questions
| 7. Realtime Applications questions
| 8. Maintainers  questions
| 
| Section 1 - Realtime Support questions
| 
| Q1 What is realtime support
| A1
| 
| Q2 How realtime works
| A2 The RT-Preempt patch converts Linux into a fully preemptible
| kernel. The magic is done with:
| 
| * Making in-kernel locking-primitives (using spinlocks) preemptible
| though reimplementation with rtmutexes:
| * Critical sections protected by i.e. spinlock_t and rwlock_t are now
| preemptible. The creation of non-preemptible sections (in kernel) is
| still possible with raw_spinlock_t (same APIs like spinlock_t)
| * Implementing priority inheritance for in-kernel spinlocks and
| semaphores. For more information on priority inversion and priority
| inheritance please consult Introduction to Priority Inversion
| * Converting interrupt handlers into preemptible kernel threads: The
| RT-Preempt patch treats soft interrupt handlers in kernel thread
| context, which is represented by a task_struct like a common userspace
| process. However it is also possible to register an IRQ in kernel
| context.
| * Converting the old Linux timer API into separate infrastructures for
| high resolution kernel timers plus one for timeouts, leading to
| userspace POSIX timers with high resolution.
| 
| Q3 What is the procedure to add realtime support
| A3 Download latest realtime preemption patch from
| http://www.kernel.org/pub/linux/kernel/projects/rt/ then related get
| vanilla kernel from http://kernel.org then patch , configure and
| compile
| 
| Section 2 - Architecture questions
| 
| Q1 Which Architecture are supporting realtime and who is maintainer
| A1
| 
| Q2 What is the procedure to support realtime in new architecture
| A2
| 
| Section 3 - Mailing list questions
| 
| Q1 realtime mailing list and archives
| A1 http://www.mail-archive.com/linux-rt-users@vger.kernel.org/
| 
| Q2 If I have some doubts or problems regarding realtime, do I need to
| send mail in realtime mailing list or linux kernel mailing list or
| both
| A2
| 
| Section 4 - Realtime Patches questions
| 
| Q1 Why I need to download realtime patches, If realtime support is in
| Linux kernel
| A1
| 
| Q2 Download latest realtime patches
| A2 http://www.kernel.org/pub/linux/kernel/projects/rt/
| 
| Q3 Where can I post my realtime patches
| A3 Please send patches for the CONFIG_PREEMPT_RT Patch Set to LKML and
| put Ingo Molnar and Thomas Gleixner on CC.
| 
| Please do not send clocksource and clockevents related patches against
| the -rt patch. Make sure they apply against the latest -hrt-dyntick
| patch. -hrt-dyntick might be a bit ahead of -rt at times, but the -rt
| patch pulls -hrt-dyntick on a regular base.
| 
| 
| Section 5 - Configuring/compiling questions
| 
| Q1 How to enable/disable realtime support
| A1
| 
| Q2 Change realtime support run time or statically
| A2
| 
| Q3 Required parameters for configuring realtime kernel
| A3
| 
| Q4 Optional parameters for configuring realtime kernel, but they
| effect realtime performance
| A4
| 
| Section 6 - Realtime samples/Performance questions
| 
| Q1 What effects by realtime support and how much and samples to test
| it and who maintains these samples
| a. scheduling, task switching time
| b. Interrupt latency
| c. Interprocess communication
| d. Filesystem
| e. Device drivers
| f. Network
| g. X-Windows
| 
| Section 7 - Realtime Applications questions
| 
| Q1 List of realtime APIs
| A1
| 
| Q2 How to write realtime applications
| A2
| 
| Q3 Which programming languages are suitable for writing realtime applications
| A3
| 
| Q4 Keep following things in mind while writing realtime applications
| A4 Taking care of the following during the initial startup phase:
| * Call directly from the main() entry the mlockall() call.
| * Create all threads at startup time of the application, and touch
| each page of the entire stack of each thread. Never start threads
| dynamically during RT show time, this will ruin RT behavior.
| * Never use system calls that are known to generate pagefaults, such
| as fopen(). (Opening of files does the mmap() system call, which
| generates a page-fault).
| * Do not use 'compile time static arrays' without initializing them
| directly after startup, before RT show time.
| 
| 
| Q5 Do I need to recompile my applications to get realtime performance
| A5
| 
| Section 8 - Maintainers questions
| 
| Q1 Maintainers of realtime kernel patch
| A1
| 
| On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
| > hello all,
| >
| > I made sections in FAQ to make it more readable.
| >
| > Thank you,
| >
| > Jaswinder Singh.
| >
| -
| To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
| the body of a message to majordomo@vger.kernel.org
| More majordomo info at  http://vger.kernel.org/majordomo-info.html
---end quoted text---

-- 
[ Luis Claudio R. Goncalves             Red Hat  -  Realtime Team ]
[ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9  2696 7203 D980 A448 C8F8 ]

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel

Thank you,

Jaswinder Singh.

On 9/29/07, Luis Claudio R. Goncalves <lclaudio@uudg.org> wrote:
> Jaswinder,
>
> On Sat, Sep 29, 2007 at 06:21:38PM +0530, Jaswinder Singh wrote:
> | Hello all,
> |
> | Please give contribution with open heart and give answers to max
> | questions as possible and give your reviews :
>
> I believe people were talking about you creating a FAQ entry in the RT Wiki
> page, at http://rt.wiki.kernel.org/index.php/Main_Page.
>
> | FAQ for realtime support in Linux Kernel
> | ---------------------------------------
> | Question Index
> | 1. Realtime Support questions
> | 2. Architecture questions
> | 3. Mailing list questions
> | 4. Realtime Patches questions
> | 5. Configuring/compiling questions
> | 6. Realtime samples/Performance questions
> | 7. Realtime Applications questions
> | 8. Maintainers  questions
> |
> | Section 1 - Realtime Support questions
> |
> | Q1 What is realtime support
> | A1
> |
> | Q2 How realtime works
> | A2 The RT-Preempt patch converts Linux into a fully preemptible
> | kernel. The magic is done with:
> |
> | * Making in-kernel locking-primitives (using spinlocks) preemptible
> | though reimplementation with rtmutexes:
> | * Critical sections protected by i.e. spinlock_t and rwlock_t are now
> | preemptible. The creation of non-preemptible sections (in kernel) is
> | still possible with raw_spinlock_t (same APIs like spinlock_t)
> | * Implementing priority inheritance for in-kernel spinlocks and
> | semaphores. For more information on priority inversion and priority
> | inheritance please consult Introduction to Priority Inversion
> | * Converting interrupt handlers into preemptible kernel threads: The
> | RT-Preempt patch treats soft interrupt handlers in kernel thread
> | context, which is represented by a task_struct like a common userspace
> | process. However it is also possible to register an IRQ in kernel
> | context.
> | * Converting the old Linux timer API into separate infrastructures for
> | high resolution kernel timers plus one for timeouts, leading to
> | userspace POSIX timers with high resolution.
> |
> | Q3 What is the procedure to add realtime support
> | A3 Download latest realtime preemption patch from
> | http://www.kernel.org/pub/linux/kernel/projects/rt/ then related get
> | vanilla kernel from http://kernel.org then patch , configure and
> | compile
> |
> | Section 2 - Architecture questions
> |
> | Q1 Which Architecture are supporting realtime and who is maintainer
> | A1
> |
> | Q2 What is the procedure to support realtime in new architecture
> | A2
> |
> | Section 3 - Mailing list questions
> |
> | Q1 realtime mailing list and archives
> | A1 http://www.mail-archive.com/linux-rt-users@vger.kernel.org/
> |
> | Q2 If I have some doubts or problems regarding realtime, do I need to
> | send mail in realtime mailing list or linux kernel mailing list or
> | both
> | A2
> |
> | Section 4 - Realtime Patches questions
> |
> | Q1 Why I need to download realtime patches, If realtime support is in
> | Linux kernel
> | A1
> |
> | Q2 Download latest realtime patches
> | A2 http://www.kernel.org/pub/linux/kernel/projects/rt/
> |
> | Q3 Where can I post my realtime patches
> | A3 Please send patches for the CONFIG_PREEMPT_RT Patch Set to LKML and
> | put Ingo Molnar and Thomas Gleixner on CC.
> |
> | Please do not send clocksource and clockevents related patches against
> | the -rt patch. Make sure they apply against the latest -hrt-dyntick
> | patch. -hrt-dyntick might be a bit ahead of -rt at times, but the -rt
> | patch pulls -hrt-dyntick on a regular base.
> |
> |
> | Section 5 - Configuring/compiling questions
> |
> | Q1 How to enable/disable realtime support
> | A1
> |
> | Q2 Change realtime support run time or statically
> | A2
> |
> | Q3 Required parameters for configuring realtime kernel
> | A3
> |
> | Q4 Optional parameters for configuring realtime kernel, but they
> | effect realtime performance
> | A4
> |
> | Section 6 - Realtime samples/Performance questions
> |
> | Q1 What effects by realtime support and how much and samples to test
> | it and who maintains these samples
> | a. scheduling, task switching time
> | b. Interrupt latency
> | c. Interprocess communication
> | d. Filesystem
> | e. Device drivers
> | f. Network
> | g. X-Windows
> |
> | Section 7 - Realtime Applications questions
> |
> | Q1 List of realtime APIs
> | A1
> |
> | Q2 How to write realtime applications
> | A2
> |
> | Q3 Which programming languages are suitable for writing realtime applications
> | A3
> |
> | Q4 Keep following things in mind while writing realtime applications
> | A4 Taking care of the following during the initial startup phase:
> | * Call directly from the main() entry the mlockall() call.
> | * Create all threads at startup time of the application, and touch
> | each page of the entire stack of each thread. Never start threads
> | dynamically during RT show time, this will ruin RT behavior.
> | * Never use system calls that are known to generate pagefaults, such
> | as fopen(). (Opening of files does the mmap() system call, which
> | generates a page-fault).
> | * Do not use 'compile time static arrays' without initializing them
> | directly after startup, before RT show time.
> |
> |
> | Q5 Do I need to recompile my applications to get realtime performance
> | A5
> |
> | Section 8 - Maintainers questions
> |
> | Q1 Maintainers of realtime kernel patch
> | A1
> |
> | On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> | > hello all,
> | >
> | > I made sections in FAQ to make it more readable.
> | >
> | > Thank you,
> | >
> | > Jaswinder Singh.
> | >
> | -
> | To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
> | the body of a message to majordomo@vger.kernel.org
> | More majordomo info at  http://vger.kernel.org/majordomo-info.html
> ---end quoted text---
>
> --
> [ Luis Claudio R. Goncalves             Red Hat  -  Realtime Team ]
> [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9  2696 7203 D980 A448 C8F8 ]
>
>

Re: FAQ for realtime support in Linux Kernel

[Theodore Tso]

On Sat, Sep 29, 2007 at 08:46:20PM +0530, Jaswinder Singh wrote:
> http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel

Thank you for putting it together and contributing it to the wiki!

I renamed the page to make the page title be a bit more succint and
less redundant (everything in rt.wiki.kernel.org is relating to the
Realtime Linux :-), and I've added a link to the FAQ to the front page
of the wiki.

As a suggestion, there's probably no need to have the revisions table,
since anyone who cares about the revision can just click on the
revisions tab on the wiki.  (BTW, I normally like to use the preview
button during the edit cycle, instead of constantly using the save
button and then looking at the new page; you might want to make sure
that "Show preview before first edit" and "Show preview before edit
box" are checked in your user preferences.)

Note by the way that some of the answers to the questions are located
elsewhere in the Wiki; which doesn't make them be bad questions, but
for example, it would probably be a good idea for some of the
questions to not try to give a partial answer, but to direct them to
areas such as the RT PREEMPT HOWTO page (for example).

Regards,

						- Ted

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Hello Ted,

Thanks for your suggestions, I tried to fixed it.

Now waiting from other guys to complete this FAQ as soon as possible ;-)

http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions

Thank you,

Jaswinder Singh.


On 9/29/07, Theodore Tso <tytso@mit.edu> wrote:
> On Sat, Sep 29, 2007 at 08:46:20PM +0530, Jaswinder Singh wrote:
> > http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel
>
> Thank you for putting it together and contributing it to the wiki!
>
> I renamed the page to make the page title be a bit more succint and
> less redundant (everything in rt.wiki.kernel.org is relating to the
> Realtime Linux :-), and I've added a link to the FAQ to the front page
> of the wiki.
>
> As a suggestion, there's probably no need to have the revisions table,
> since anyone who cares about the revision can just click on the
> revisions tab on the wiki.  (BTW, I normally like to use the preview
> button during the edit cycle, instead of constantly using the save
> button and then looking at the new page; you might want to make sure
> that "Show preview before first edit" and "Show preview before edit
> box" are checked in your user preferences.)
>
> Note by the way that some of the answers to the questions are located
> elsewhere in the Wiki; which doesn't make them be bad questions, but
> for example, it would probably be a good idea for some of the
> questions to not try to give a partial answer, but to direct them to
> areas such as the RT PREEMPT HOWTO page (for example).
>
> Regards,
>
>                                                - Ted
>

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Thank you Theodore Ts and Remy Bohmer for updating :

http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions

And giving us such a valuable information.

Thank you,

Jaswinder.


On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> Hello Ted,
>
> Thanks for your suggestions, I tried to fixed it.
>
> Now waiting from other guys to complete this FAQ as soon as possible ;-)
>
> http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
>
> Thank you,
>
> Jaswinder Singh.
>
>
> On 9/29/07, Theodore Tso <tytso@mit.edu> wrote:
> > On Sat, Sep 29, 2007 at 08:46:20PM +0530, Jaswinder Singh wrote:
> > > http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel
> >
> > Thank you for putting it together and contributing it to the wiki!
> >
> > I renamed the page to make the page title be a bit more succint and
> > less redundant (everything in rt.wiki.kernel.org is relating to the
> > Realtime Linux :-), and I've added a link to the FAQ to the front page
> > of the wiki.
> >
> > As a suggestion, there's probably no need to have the revisions table,
> > since anyone who cares about the revision can just click on the
> > revisions tab on the wiki.  (BTW, I normally like to use the preview
> > button during the edit cycle, instead of constantly using the save
> > button and then looking at the new page; you might want to make sure
> > that "Show preview before first edit" and "Show preview before edit
> > box" are checked in your user preferences.)
> >
> > Note by the way that some of the answers to the questions are located
> > elsewhere in the Wiki; which doesn't make them be bad questions, but
> > for example, it would probably be a good idea for some of the
> > questions to not try to give a partial answer, but to direct them to
> > areas such as the RT PREEMPT HOWTO page (for example).
> >
> > Regards,
> >
> >                                                - Ted
> >
>

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Hello all,

I tried to fill remaining entries in :
http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions

Please it out, is these OK.

Thank you,

Jaswinder Singh.

On 9/30/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> Thank you Theodore Ts and Remy Bohmer for updating :
>
> http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
>
> And giving us such a valuable information.
>
> Thank you,
>
> Jaswinder.
>
>
> On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> > Hello Ted,
> >
> > Thanks for your suggestions, I tried to fixed it.
> >
> > Now waiting from other guys to complete this FAQ as soon as possible ;-)
> >
> > http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
> >
> > Thank you,
> >
> > Jaswinder Singh.
> >
> >
> > On 9/29/07, Theodore Tso <tytso@mit.edu> wrote:
> > > On Sat, Sep 29, 2007 at 08:46:20PM +0530, Jaswinder Singh wrote:
> > > > http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel
> > >
> > > Thank you for putting it together and contributing it to the wiki!
> > >
> > > I renamed the page to make the page title be a bit more succint and
> > > less redundant (everything in rt.wiki.kernel.org is relating to the
> > > Realtime Linux :-), and I've added a link to the FAQ to the front page
> > > of the wiki.
> > >
> > > As a suggestion, there's probably no need to have the revisions table,
> > > since anyone who cares about the revision can just click on the
> > > revisions tab on the wiki.  (BTW, I normally like to use the preview
> > > button during the edit cycle, instead of constantly using the save
> > > button and then looking at the new page; you might want to make sure
> > > that "Show preview before first edit" and "Show preview before edit
> > > box" are checked in your user preferences.)
> > >
> > > Note by the way that some of the answers to the questions are located
> > > elsewhere in the Wiki; which doesn't make them be bad questions, but
> > > for example, it would probably be a good idea for some of the
> > > questions to not try to give a partial answer, but to direct them to
> > > areas such as the RT PREEMPT HOWTO page (for example).
> > >
> > > Regards,
> > >
> > >                                                - Ted
> > >
> >
>

Re: FAQ for realtime support in Linux Kernel

[Remy Bohmer]

Hello Jaswinder,

I have some troubles with the question:
'What effects by realtime support and how much and samples to test it
and who maintains these samples?'

I doubt anyone can fill in this paragraph properly. It is too vague,
and the figures you ask are different for every architecture and
processor type/speed that is supported.

What do you think?


Kind Regards,

Remy Bohmer


2007/10/1, Jaswinder Singh <jaswinderlinuxrt@gmail.com>:
> Hello all,
>
> I tried to fill remaining entries in :
> http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
>
> Please it out, is these OK.
>
> Thank you,
>
> Jaswinder Singh.
>
> On 9/30/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> > Thank you Theodore Ts and Remy Bohmer for updating :
> >
> > http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
> >
> > And giving us such a valuable information.
> >
> > Thank you,
> >
> > Jaswinder.
> >
> >
> > On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@gmail.com> wrote:
> > > Hello Ted,
> > >
> > > Thanks for your suggestions, I tried to fixed it.
> > >
> > > Now waiting from other guys to complete this FAQ as soon as possible ;-)
> > >
> > > http://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
> > >
> > > Thank you,
> > >
> > > Jaswinder Singh.
> > >
> > >
> > > On 9/29/07, Theodore Tso <tytso@mit.edu> wrote:
> > > > On Sat, Sep 29, 2007 at 08:46:20PM +0530, Jaswinder Singh wrote:
> > > > > http://rt.wiki.kernel.org/index.php/FAQ_for_realtime_support_in_Linux_Kernel
> > > >
> > > > Thank you for putting it together and contributing it to the wiki!
> > > >
> > > > I renamed the page to make the page title be a bit more succint and
> > > > less redundant (everything in rt.wiki.kernel.org is relating to the
> > > > Realtime Linux :-), and I've added a link to the FAQ to the front page
> > > > of the wiki.
> > > >
> > > > As a suggestion, there's probably no need to have the revisions table,
> > > > since anyone who cares about the revision can just click on the
> > > > revisions tab on the wiki.  (BTW, I normally like to use the preview
> > > > button during the edit cycle, instead of constantly using the save
> > > > button and then looking at the new page; you might want to make sure
> > > > that "Show preview before first edit" and "Show preview before edit
> > > > box" are checked in your user preferences.)
> > > >
> > > > Note by the way that some of the answers to the questions are located
> > > > elsewhere in the Wiki; which doesn't make them be bad questions, but
> > > > for example, it would probably be a good idea for some of the
> > > > questions to not try to give a partial answer, but to direct them to
> > > > areas such as the RT PREEMPT HOWTO page (for example).
> > > >
> > > > Regards,
> > > >
> > > >                                                - Ted
> > > >
> > >
> >
>

Re: FAQ for realtime support in Linux Kernel

[Theodore Tso]

On Mon, Oct 01, 2007 at 10:18:15PM +0200, Remy Bohmer wrote:
> I doubt anyone can fill in this paragraph properly. It is too vague,
> and the figures you ask are different for every architecture and
> processor type/speed that is supported.

I've already replaced that question with one asking about what kind of
performance one could expect, and answered it with the standard "it
depends" answer.  I moved it to the general "Getting Started" section.

At some point it would be good to add some commentary about the
resulting throughput degradation (which is why I kept the question
open-ended about "performance", instead of "latency").

						- Ted

Re: FAQ for realtime support in Linux Kernel

[Jaswinder Singh]

Thanks for your updates.

So here another question arise, how I know that -rt patch I applied is
working properly. check my "Cyclictest expected results".

If we have some magical numbers to test -rt patch, It will be great!!

Thank you,

Jaswinder Singh.


On 10/2/07, Theodore Tso <tytso@mit.edu> wrote:
> On Mon, Oct 01, 2007 at 10:18:15PM +0200, Remy Bohmer wrote:
> > I doubt anyone can fill in this paragraph properly. It is too vague,
> > and the figures you ask are different for every architecture and
> > processor type/speed that is supported.
>
> I've already replaced that question with one asking about what kind of
> performance one could expect, and answered it with the standard "it
> depends" answer.  I moved it to the general "Getting Started" section.
>
> At some point it would be good to add some commentary about the
> resulting throughput degradation (which is why I kept the question
> open-ended about "performance", instead of "latency").
>
>                                                - Ted
>

Re: FAQ for realtime support in Linux Kernel

[Girish kathalagiri]

Hi all,
This is a FAQ section is really great.

Also I had few more questions .. What are the best practices for
testing? which tests correctness and deterministic behavior.
something like ...
http://tree.celinuxforum.org/CelfPubWiki/RealtimeTestingBestPractices

And also question regarding the Real-Time SMP based system, (ex.
multi-core systems and RT_PREEMPT).This is a bit vague , but something
which addresses the SMP based system.

-- 
Thanks
   Giri

Re: FAQ for realtime support in Linux Kernel

[Remy Bohmer]

Hello Theodore,

> At some point it would be good to add some commentary about the
> resulting throughput degradation (which is why I kept the question
> open-ended about "performance", instead of "latency").

Is there still a throughput degradation noticeable on some platforms?
I know for sure it was there in the past, but I thought these were all
fixed by now.
AFAIK: The latest kernels have fixed the netwerk performance
degradation bug, and on Dual-Core we even notice a performance
improvement compared to non-RT.

Kind Regards,

Remy Bohmer

2007/10/2, Theodore Tso <tytso@mit.edu>:
> On Mon, Oct 01, 2007 at 10:18:15PM +0200, Remy Bohmer wrote:
> > I doubt anyone can fill in this paragraph properly. It is too vague,
> > and the figures you ask are different for every architecture and
> > processor type/speed that is supported.
>
> I've already replaced that question with one asking about what kind of
> performance one could expect, and answered it with the standard "it
> depends" answer.  I moved it to the general "Getting Started" section.
>
> At some point it would be good to add some commentary about the
> resulting throughput degradation (which is why I kept the question
> open-ended about "performance", instead of "latency").
>
>                                                 - Ted
>