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Old 05-04-2011, 03:16 PM   #1
Galbatross
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Is there a PID 0?


Hello,

I'm currently doing some debugging and I'm attempting to find out which task is running between two events. I'm using a bus analyzer to trigger after I configure my hardware and stopping it once an overflow event takes place. During this period, I write the PID of the current task running every millisecond by checking the variable 'currnet->pid'. It seems that the task's PID right before my overflow event is 0. A quick 'ps' reveals that there is not a task 0.

I'm curious if anyone would know off-hand what a PID 0 represents? If I had to guess, I would say it's an interrupt handler, but I can't be positive. Any feedback is very appreciated!

Thanks,
Galbatross.
 
Old 05-04-2011, 03:30 PM   #2
MensaWater
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The lowest PID in UNIX/Linux is PID 1 which is init. All processes are children of init in the process table heirarchy.

My guess is that you're not seeing PID 0 but rather are getting a non-existent value being interpreted as "0" before you have a PID number assigned.
 
Old 05-04-2011, 06:12 PM   #3
syg00
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Nope. This comes up continually.
Have a read of this for example.
 
Old 05-05-2011, 07:49 AM   #4
Galbatross
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Thanks

Very helpful, thank you.

Galbatross
 
Old 05-05-2011, 08:02 AM   #5
brownie_cookie
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if you're pleased with the answer, please mark this thread as solved !

Have a nice day and enjoy LQ

 
  


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