[MPlayer-users] How to pause mencoder

[D Richard Felker III]

On Fri, Dec 26, 2003 at 01:30:55AM +1000, Adam Nielsen wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> > It's not a problem with process scheduling, that's done rather well
> > (at least in 2.4, dont know about 2.6), but the problem is the
> > PC architecture which has a poor I/O system that blocks everything
> > and Linux which has problem handling big I/O loads.
> 
> Well, at the risk of starting a flamewar, Windows never used to make my mouse 
> cursor go jerky while it was heavily accessing the disk... (and yes, I've got 
> DMA enabled.)  So it's definitely a Linux issue.

Windows moves the mouse cursor from the interrupt handler, i.e.
including video code in serial/ps2/usb interrupt handler! This is
rather bad design and leads to crashes, but it looks "pretty" for
users. On the other hand, if your X server is swapped or not getting
cpu time for some other reason, it won't be able to update the
graphical cursor until it runs again.

> I tried installing the 
> preemptive kernel patch a while ago though, and that made a big improvement 
> which is why I think it's a multitasking issue.  If the kernel is stuck in a 
> long I/O operation as you say and has blocked, then no other processes can 
> run (which is presumably why the performance is even worse when playing over 

Preempt allows processes to run while the kernel is blocked in doing
something.

> And yes, I do agree that process scheduling is done well in Linux, but it 
> would still be nice to have an "idle" priority like in win32 - then you can 
> run a program in the background and it will give up *all* its CPU cycles 
> should the need arise (as opposed to nice -19 which only gives up most of the 
> CPU cycles.)  It sure beats manually suspending distributed.net/SETI/etc. to 
> speed up mencoder ;-)

For 2.4, the -ck patch series replaced nice levels 19/20 with a true
idle priority. I don't know if it still exists for 2.6. You might want
to try it. As for seti/distributed.net/etc., you should think about
whether you really want to pay a higher electric bill and wear out
your hardware quicker just to help them compute something. "Spare"
cycles aren't spare; when they're not used, the cpu powers down and
conserves a lot of energy.

Rich