Re: [Playerstage-developers] Player-CVS being restructured?

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 454-5900

On Apr 30, 2007, at 6:53 PM, Kevin Barry wrote:

> Most of the issues I was having before are no longer. I wonder if I  
> checked out right when someone was checking in, or my checkout  
> silently failed part way through or something. But I'm still having  
> libtool issues. If I use the libtool script from player-2.0.3 it  
> builds fine.

The libtool script that is generated by autoreconf doesn't work?   
What errors do you see?

> On Mac when Player doesn't have any clients connected, the CPU  
> usage jumps to 100%. Once a client connects, it drops  
> significantly. This doesn't seem to effect Linux however. (I didn't  
> investigate the TCP/UDP libraries to fully understand why. It could  
> be that my patch is really just covering up a bigger problem)

I've seen the same thing.  This is because OS X has a smaller  
scheduling timeslice than Linux (a result of the microkernel  
architecture, I suppose).  There is in fact a sleep in Player's main  
loop, but only for 1us.  On Linux, this sleep is impossible to  
achieve, but OS X can just about do it, resulting in a busy loop.  We  
fixed this by increasing the main loop sleep to 1ms, which seems to  
work well on both platforms, and will still allow for 1KHz operation.

> To fix it I've added a check to see if we have no clients, if  
> that's the case, it sleeps for .1 seconds.
>
> The only possible downside I can think of (But I could be  
> overlooking something! Someone double check me) is that there is up  
> to a .1 second additional delay for the first client to connect.  
> This seems quite acceptable.

There can be drivers running with no clients connected, and if any of  
them are non-threaded (i.e., updated from the main server thread),  
such as Stage, then this extra sleep will slow them down.  This is  
not a good thing, not because of the length of the sleep, but because  
of the significant change in timing for such drivers depending on  
whether clients are connected.

	brian.