[PLUG] SMP kernel timebase question

Daggett, Steve Steve.Daggett at fiserv.com
Fri Sep 5 11:08:01 UTC 2003


Galen Seitz:
> In an SMP kernel, what is the impact of the CPU timebases not being
> synchronized?  For instance, imagine a two CPU system where 
> each CPU's timer
> interrupt is 180 degrees out of phase relative to the other.  
> How might this impact performance or behavior?
> 
  I don't think it would make a difference.  My SMP machine has a
"ksoftirqd" process for each CPU.  Tasks get pulled off the queue and then
run on the "correct" processor.  The definition of "correct" depends on the
kernel version you're using.

  Each task doesn't know or care what CPU it's scheduled to run on.  Good
SMP programming practices should take care of any other issues.  

Steve D...




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