[Intel-gfx] Interrupt latency on some 945GM platforms

[Vasily Khoruzhick]

В сообщении от 14 of September 2010 03:55:32 автор Venkatesh Pallipadi 
написал:

> Whats the clockevent in this case ("Tick Device" section of
> /proc/timer_list). clocksource= option only changes the clocksource used
> to maintain
> timeofday. But, timer interrupt (clockevent) source will not change.
> Wondering how just the clocksource change is making the diff here..
> 
> Also, if clocksource tsc has a higher rating than HPET. The reason
> HPET is getting used as clocksource in the first place seems to be due
> to TSC is not a dependable clocksource on this platform (may be it
> stops in C3). So, I am not sure forcing it to tsc will be a good
> thing. May be clocksource=acpi_pm is a better thing to try.
> 
> Thanks,
> Venki

I investigated it a bit and found out that single nohz=off option helps. Just 
changing clocksource doesn't help, but it works smoothly with any clocksource 
with nohz=off. So, it seems that something wrong with intel driver while 
system is in tickless mode. 

Regards
Vasily
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