Re: [gentoo-user] I want to play movies without hangs

[Alex Schuster]

Mark Knecht writes:

> On Mon, May 7, 2012 at 5:41 AM, Alex Schuster <wonko@×××××××××.org>
> wrote:
> > Some while ago, I wrote:
> >
> > [
> > mplayer stutters when I/O is going on, even hangs for seconds when I
> > do a dd if=/dev/zero of=somefile bs=1M
> > ]
[...]
>    OK, fire up two terminals. In one run top, hit 1 & z so you see all
> your CPUs and then watch CPU usage. In the second terminal su to root
> and run iotop -o. Now, watch for a few minutes and get a feel for
> what's going on when video is not running. Then start your video and
> watch IO usage and CPU usage. Where's the problem?
>
>    Once you get an idea where the bottleneck is we can address what a
> solution might be. In general, if the CPUs aren't maxed out and it's
> an I/O problem then usually a bit more buffering is a simple solution.
> Other more draconian solution might be a real-time kernel with a
> player (if there is one) that is set up for real-time playback.
>
>    Looking forward to hearing your test results.

Thanks for your support, Mark!

I did this already, but sometimes I do not notice anything. I guess it's
short I/O operations in that case. CPU load is not the problem, and it
happens for both high-quality videos and small ones. 
Currently iotop shows stuff like kjournald, kworker, kdeinit4,
akonadiserver, firefox. And lots of virtuoso-t and nepomuk when I enable
indexing again, which I just suspended.
And mplayer of course, it shows up in about every 2nd redisplay, which
happens every second.

Well... but when I do the same in the other window manager, it seems I
see fewer processes then. Are they mostly suspended when I am on another
display?
And I should fire up the same stuff (Firefox, Chromium, maybe KDEPIM
stuff) in the other WM and see if this makes things worse. But I'll do
this tomorrow. Thanks for the inspiration, though, at least I have
something more to try now.

The interrupts are very small normally, but noticeable, annoying and
somewhat embarrassing. When they just happened I only noticed akonadi and
kjournald during that time. I can force larger interrupts by doing my dd
command.

But anyway - my intention is not so much to find out what all these
I/O processes are and how to make them calm down, renice them or whatever.
Four cores @ 3.6 GHz just should be able to play movies without any
interruption. And it _is_ possible, when I start the playback on another
window manager, while KDE is still running on the other display.

I could just switch to, um, ummmm.... Gnome maybe... or Xfce4... or
something else, but I would not like to do so. Despite by big KDE
problems. I hate KDE. But I still want it. I feel mad.

	Wonko