Re: Responsiveness of 2.6.0-Test9

[Nick Piggin <piggin@cyberone.com.au>]

Erwin Telser wrote:

>>Erwin Telser wrote:
>>
>>>Are there things to observe when switching from 2.4 to 2.6, if I want the
>>>same responsiveness? I'm asking because I' ve made the following
>>>observation. (I always had the feeling, 2.4 seems to faster, but this is
>>>the first time it' s very obvious)
>>>
>>>I' ve connected two monitors on a Matrox G550. One runs with DRI the other
>>>one doesn't (not possible with the current driver). The Monitor with DRI
>>>I'm using as a TV Set, watching movies with xawtv. (With a bttv 878 tuner
>>>card).
>>>
>>>Now with the 2.4.22 kernel (preemptible patch aplied) I can play the
>>>little game kbounce on the other monitor, without to notice any slowdown,
>>>no matter, whether xawtv is running or not.
>>>
>>>But with the 2.6 Kernel (compiled with preemptible option) the bouncing
>>>balls slow down considerably, as soon as I move the mouse.
>>>
>>>I know the whole thing is a little foolish. But anyway, are there some
>>>tricks to get the same responsiveness?
>>>
>>Hi,
>>Your report is not foolish at all ;)
>>Please make sure your X process is at default static priority, 0.
>>Report back if you are still having problems. What sort of processor
>>do you have? Is your 2.6 video driver running with the same sort of
>>acceleration as your 2.4 one (do you get the same frame rate in glxgears)?
>>
>
>I installed X from scratch and didn't edit any start script. so I assume, that 
>it runs with priority 0. The processor is an Intel P4 2000MHz in an ASUS 
>P4B266 Board. If I compare the frames per second with glxgears there is a 
>slight advantage for 2.4
>

renice 0 `pidof X`

>
>2.4: 
>with DRI 358 - 364
>without DRI 181 - 198
>
>2.6
>with DRI 350 - 362
>without DRI 180 - 187
>
>An even better way to show the differenze between 2.4 and 2.6 is to change the 
>size of the xawtv window. If I do that, the slowdown is quite significant. 
>But it happens only with xawtv. If I do the same with konqueror or MPlayer, 
>nothing happens. A very strange thing are the values I get from ksysguard
>
>Kernel 2.4, glxgears
>user load: 3% - 4%
>system load: 95%
>IRQ per second: ~100
>
>Kernel 2.6, glxgears
>user load: 15%
>system load: 85%
>IRQ per second: ~1100 
>
>Kernel 2.4, xawtv
>user load: 2%
>system load: 0%
>IRQ per second: ~100
>
>Kernel 2.6, xawtv
>user load: 9%
>system load: 0%
>IRQ per second: ~1060 
>
>Kernel 2.4, MPlayer
>user load: 35%
>system load: 2%
>IRQ per second: ~1170
>
>Kernel 2.6, MPlayer
>user load: 42%
>system load: 2%
>IRQ per second: ~2130
>
>Something is causing a high IRQ load with kernel 2.6. Probably an APIC 
>problem?
>

It is the timer interrupt. Now happens 1000 per second instead of 100.
This might just be the reason why you are seeing a different balance, the
collection of cpu statistics is more precise.