Re: rt_make_soft_real_time hangs my process

Trivially recalling that Linux threads are substantially processes sharing a memory space by default, every thread of a process can be made hard-soft as you like, under RTAI.
So if you have a thread that in Linux's hands to acquire frames through a not hard real time RTAI driver and want that as soon as a complete frame has been acquired it is  process in hard real time immediately you have just to enable (using rt_thread_init or rt_task_init_schmod) the acquisition LINUX thread to using RTAI functions, mating it to another hard real time hardened RTAI thread that waits for being awaken by the acuisition thread. That done define a multiple frames buffer, let the acquisition frame acquire frames continuously passing  an available  frame index to the hard real time thread. The mechanisms to be used can be just a semephore with the index being a per process variable, a suspend-resum,  an rpc_receive with the index passed through and rt_send.
Hoping I undertood your proble, sorry if my suggestions were trivial stuff.

Paolo

________________________________________
From: Duane AW. Jeffery [[email protected]]
Sent: Friday, June 3, 2016 6:54 PM
To: Paolo Mantegazza; '[email protected]'
Subject: RE: rt_make_soft_real_time hangs my process

Its running on a video processing software, and we're doing it to ensure our image analysis routine is not interrupted.

Each time a new frame arrives from the camera, it goes hard, processes the frame, and returns soft.  Framerates range from 100 to ~9000 fps depending on ROI.

I think I might know what's going on though.  The process that this runs on creates a separate thread for acquiring the frames from the camera with its affinity set so that it runs on a separate core, and the realtime part is only for the processing of a frame after it arrived.  Both functions run under the same process though (ie. ps aux only shows one item), and so I think that might be my problem.  Can I even legally call rt_make_hard_real_time() on a multithreaded process?

-Duane

-----Original Message-----
From: Paolo Mantegazza [mailto:[email protected]]
Sent: Friday, June 03, 2016 9:59 AM
To: Duane AW. Jeffery <[email protected]>; '[email protected]' <[email protected]>
Subject: RE: rt_make_soft_real_time hangs my process

Can you provide the frequency of the hard7soft switches?
If you a doing it for a controlled approach to Linux syscalls , try letting RTAI take care of it and see what happens. In such a view you might even try  using a Linux  server .
That said, eventually this is the case in which it should not be too complex to set a neutral test up, so that I cantry to diagnose the problem you are wittnessing.

Paolo
________________________________________
From: Rtai [[email protected]] on behalf of Duane AW. Jeffery [[email protected]]
Sent: Friday, June 3, 2016 3:12 PM
To: '[email protected]'
Subject: [Rtai] rt_make_soft_real_time hangs my process

Hi all,

I'm running a shiny new system on Linux 4.1.18 w/ RTAI 5 from vulcano, and it seems to be going well.  (System is derived from a Slackware 14.1 install)

I seem to be having a small problem with one of my applications where it calls into rt_make_soft_real_time() which never returns.  It previously calls rt_make_hard_real_time(), and calls the pair in a loop, so it switches back and forth fairly frequently.

Any ideas?

-Duane
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