Re: [ck] CPU load balance or one task domination =?iso-8859-13?q?under=09linux-2=2E6=2E7-ruby-s77?=

[Aivils <ai...@un...>]

On Monday 05 July 2004 21:19, Con Kolivas wrote:
> Aivils wrote:
> > Hi All!
> > 
> > 	I try multiple local user linux box.
> > All 2.6.XX kernel versions from 2.6.0 up to 2.6.7 do one task domination.
> > I applay before staircase 7 and now staircase 7.7
> > 
> > Anyway if two users run games simultaneous, then one game allways
> > dominate.
> > If i set "nice -n +1 game-bin"  for each user , then both games
> > became choppy, because lost priority against system tasks.
> > 
> > Second phenomen - tuxracer under 2.4.26 take 1%-3% CPU time,
> > but under 2.6.7-s77 it eat 80%. As result i cannot test thiny games
> > simultaneous, because thiny goes fat and choppy.
> > 
> > Does know anybody is this phenomen realy depended from task
> > scheduler alghoritm?
> > 
> > May be that is system call queue?
> 
> Hi
> 
> Please try staircase7.8 and use
> echo 0 > /proc/sys/kernel/interactive

Ok. I was try two kernels 2.6.7,
1) with vanilla scheduler non-preemptive,
2) staircase 7.8 w/ echo 0 > /proc/sys/kernel/interactive
both have 100Hz kernel timer
Two users start game
otto> nice -n +10 game-bin
fritz> nice -n +10 game-bin

Gamers feeling under both kernels are identical.
Kernel normal split resources almost righteous for each game.
BUT THIS IS NOT 2.4.XX FEELING!

Seems  2.6.XX rescheduling time is larger than magic 10-30m sec
which gamer cannot feel visual.
Under 2.4.XX on second game start fisrt gamer feel on frames per
second (fps) decrease, but game still smooth.
Under 2.6.XX on second game start fisrt gamer feel horrible
delays. Almost game become unplayable.

Under 2.6.XX is impossible start two simultaneous games without
nice +

> cpu time accounting can be out by a great margin changing Hz (as happens 
> between 2.4 and 2.6). Higher Hz will always show higher cpu usage even 
> if the usage is the same. If a task waes up at just the right time 
> frequently enough it can appear to use 10 times as much cpu.
100 Hz does the work :)
tuxracer is back and take 1% CPU as under 2.4.XX

Me never  trust lest usage is the same as under 2.4.XX, because two
tuxracers under 2.6.7 distrub each other!

Aivils