Re: gtkmm Monitoring IO example

[Sanne Ausma <sanne sanneausma nl>]

Thank for your answer, this was what I feared (I am on Linus btw).
Coming from a C background, I know there is a more efficient way of 
doing this.

I did figure out how to get the CPU load down without re-implementing 
it.
The only change I made to the example is the flags the call to open from 
O_RDONLY to O_RDWR.
The example works as expected but now without the high CPU load.

Should I report this somewhere?

Sanne


On 2015-09-25 15:13, Kjell Ahlstedt wrote:
> 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
> > _______________________________________________