Re: gtkmm Monitoring IO example

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

When I tested the input example program on my dual-core PC, I got the 
same result: The CPU load on one of the cores is 100% after something is 
written to the fifo. Most of the relevant code is in glib. I don't know 
all details, but this is what I found:

Before anything is written to the fifo, the program waits at
   read_fd = open("testfifo", O_RDONLY);
without using much CPU time (perhaps no time at all).
Once the fifo contains data to read, open() returns, and the program 
enters the main loop at
   app->run();
After that, the fifo is monitored by polling. Polling is inefficient. 
Probably it's the only possible way that the OS offers. It does seem a 
bit extreme to use all available CPU time for polling, but probably it's 
normal behaviour.

Kjell

Den 2015-09-25 kl. 08:04, skrev Sanne Ausma:
> I am trying the Gtkmm Monitoring I/O example from the gtkmm-tutorial.
> (https://developer.gnome.org/gtkmm-tutorial/unstable/sec-monitoring-io.html.en) 
>
>
> The example works but after something has been written to the fifo, 
> top shows the CPU load going to 100%.
> I have tried the example with both gtkmm 3.0 and 2.4 but the result is 
> the same.
>
> Is this normal behaviour?
>
> Thanks,
>
> Sanne
> _______________________________________________