real time question : RR vs FF?

[Victor henri]

I answer to myself

It was quite easy to find... 
In the 'testrtpool.c' file, in the 'default-push' function, I just had to replace "SCHED_RR" by "SCHED_FIFO"
On the other hand, 'param.sched_priority' is set to to 50, which can be changed also according to the priority one wants to give to the process;

Victor

From: nadaeck at hotmail.com
To: gstreamer-devel at lists.freedesktop.org
Subject: real time question : RR vs FF?
Date: Thu, 28 Apr 2011 04:34:39 +0200








Hello

I have made an app that displays the harmonics in 3d.

I want to be able to run it in real-time; I have used the 'rtpool-test' code from the gstreamer core examples (streams->rtpool-test.c) and it works. However, I have seen that this grants me a priority of 90 with a 'RR' policy. Is it possible to change the code code to get 'FIFO' policy? If yes, please how could I do this? I have tied to use the set_schedparam code, but I got the 'Invalid argument' during 'pthread_attr_setschedparam (&attr, &sched)' error... (as well as starting the app with 'chrt -r -p my-pid')

Another question : this code grants real time for Gstreamer code, but what about other code code (not Gstreamer) that follows it? The app is written like this : GTK GUI with a 'Play" button, that starts playing the sound with Gstreamer, and the 'spectrum' element send messages to the bus; everytime the "message handler" function retrives the values of the spectrum, there is a call to a function that display the values of the spectrum in a SDL/OpenGL window. My question is : is the display in the SDL/OpenGL window done also with the RR policy or back with TS policy?

When I run the app (its name is 'spectrum3d', then when I run 'ps -cLe' in a terminal to see all the threads of the app, I see this :

 5265  5265 TS   19 pts/0    00:00:01 spectrum3d
 5265  5267 TS   19 pts/0    00:00:00 threaded-ml
 5265  5268 TS   19 pts/0    00:00:00 threaded-ml
 5265  5270 TS   19 pts/0    00:00:00 task0
 5265  5271 TS   19 pts/0    00:00:00 spectrum3d
 5265  5272 RR   90 pts/0    00:00:01 alsasrc:src

The 1st pid is the Gtk GUI; the last one must be the gstreamer sound reading, since its policy is RR; but I don't know what the other pid represent...

thanks for your help

Victor
 		 	   		  

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