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Realtime Workshop Slides?

DISCUSSION Daniel Wagner 3 participants 5 messages Nov 25, 2013 – Dec 1, 2013 1 message not in the archive

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Daniel Wagner

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#0 lore raw

Hi Steven,

I'd like to write up a summary how to write a RT application. Instead of writing yet another document, I really like to extend (if needed) this here

https://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application

My memory is quite bad so I am not sure if there is anything missing on this page, compared with your presentation durin the RTWS. If you don't mind sharing the slide, I could try to add missing stuff :)

(Obviously, it will be in Engrish :P)

cheers,
daniel

A message that is not in the archive (sent off-list or not yet received): 20131125111526.5e17c989@eeyore

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#2 lore raw

Hi Philipp,

Quoted 16 lines · Philipp Überbacher
Quoted 13 lines · On Mon, 25 Nov 2013 10:10:37 +0100 Daniel Wagner <[email protected]> wrote:

Hi Steven,

I'd like to write up a summary how to write a RT application. Instead of writing yet another document, I really like to extend (if needed) this here

https://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application

My memory is quite bad so I am not sure if there is anything missing on this page, compared with your presentation durin the RTWS. If you don't mind sharing the slide, I could try to add missing stuff :)

Quoted 6 lines
Quoted 4 lines

(Obviously, it will be in Engrish :P)

cheers,
daniel

Hi Daniel, hi list.

I think your mail didn't make it to list so far (at least there is no Cc).

Quoted 2 lines

I would appreciate such a thing (for the time when I finally come around to write some audio application).

Looking forward to it :)

Quoted 4 lines

One thing that's a bit unclear to me: should mlockall() be used with the MCL_FUTURE flag? Or to rephrase this, does mlockall(MCL_FUTURE) somehow look ahead and immediately lock all pages the process will ever need?

According mlockall() man page:

MCL_CURRENT Lock all pages which are currently mapped into the address space of the
process.

MCL_FUTURE Lock all pages which will become mapped into the address space of the process
in the future. These could be for instance new pages required by a growing heap and stack as well as new memory mapped files or shared memory regions.

If MCL_FUTURE has been specified, then a later system call (e.g., mmap(2), sbrk(2), mal‐ loc(3)), may fail if it would cause the number of locked bytes to exceed the permitted maximum (see below). In the same circumstances, stack growth may likewise fail: the ker‐ nel will deny stack expansion and deliver a SIGSEGV signal to the process.

Mostlikely you want to use both flags. See also the examples

https://rt.wiki.kernel.org/index.php/Simple_memory_locking_example
https://rt.wiki.kernel.org/index.php/Dynamic_memory_allocation_example
https://rt.wiki.kernel.org/index.php/Threaded_RT-application_with_memory_locking_and_stack_handling_example

Quoted 2 lines

Another useful thing would be a (probably incomplete) list of common calls that are known to cause problems in an rt context.

Absolutely.

cheers,
daniel

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#3 lore raw
In reply to Daniel Wagner
Quoted 11 lines · On Mon, 25 Nov 2013 10:10:37 +0100 Daniel Wagner <[email protected]> wrote:

Hi Steven,

I'd like to write up a summary how to write a RT application. Instead of writing yet another document, I really like to extend (if needed) this here

https://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application

My memory is quite bad so I am not sure if there is anything missing on this page, compared with your presentation durin the RTWS. If you don't mind sharing the slide, I could try to add missing stuff :)

My slides are already public. Add what you want.

-- Steve

Quoted 5 lines

(Obviously, it will be in Engrish :P)

cheers,
daniel

#4 lore raw

Hi Steve,

I am also interested in the slides. Where can I find them ?

Best regards,

Matthias

------ Originalnachricht ------
Von: "Steven Rostedt" <[email protected]>
An: "Daniel Wagner" <[email protected]>
Cc: [email protected]
Gesendet: 25.11.2013 18:08:39
Betreff: Re: Realtime Workshop Slides?

Quoted 31 lines
Quoted 6 lines · On Mon, 25 Nov 2013 10:10:37 +0100 Daniel Wagner <[email protected]> wrote:

Hi Steven,

I'd like to write up a summary how to write a RT application. Instead of writing yet another document, I really like to extend (if needed) this here

Quoted 6 lines

https://rt.wiki.kernel.org/index.php/HOWTO:_Build_an_RT-application

My memory is quite bad so I am not sure if there is anything missing on this page, compared with your presentation durin the RTWS. If you don't mind sharing the slide, I could try to add missing stuff
:)

My slides are already public. Add what you want.

-- Steve

Quoted 5 lines

(Obviously, it will be in Engrish :P)

cheers,
daniel

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