SMP weirdness in -CURRENT

[Atte Peltomaki]

> > So.. What's going on? Am I the only one who notices these things? I have a feeling this only happens when the system load is high, not when the user load is high. And the funny thing is - my openoffice build (in this case) is running with nice -n 10, so even its priority is low.
> 
> > Is this related to SCHED_ULE, should I try with SCHED_BSD? I thought the real strengths of SCHED_ULE only shows on SMP, am I wrong?
> 
> I have been experiencing same symptoms you described on two of my SMP 
> boxes, long time now. And I'm really going to get to the bottom of
> this, tried switching NIC's, audio cards, UP kernel, with and without
> ACPI.. I'll let you know when I come up with something useful. 
> 
> At least the symptoms surface a lot worse when all the -current kernel
> debugging options are turned on (=more system cpu load)

Allright, removing all debugging stuffs made things pretty good. With the
debug symbols, cpu system load was constantly around 15%. 

Now, If I load the CPU a lot, like make -j10 buildworld, cpu loads are 
between 50% and 100% all the time, but music plays just fine without
any kind of lag. 

But If I do something that puts system cpu load even over 30%, things 
get very jerky. No matter if the loading process is niced to 20 and 
xmms (or whatevery player) is niced -20. 


Atte Peltomaki
http://kameli.org