Re: [LIP] sleep function - perform activity every 10 seconds

  Hi,
    Assuming if you call sleep every 1 sec then performance wise it will
affect,
   I think sleep is implemented as a system call(takes some time to exeucte
i.e switching from user to kernel and viceversa,getting the current time
etc..) + check you are  performing will take some time.hence you will not
land up at exactly 10 sec boundary.
  instead use signal functionality(viz SIGALRM).


  Regards,
  Santosh

  ----- Original Message ----- 
  From: "Rohan Almeida" <[email protected]>
  To: <linux-india-programmers-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
  Sent: Monday, April 26, 2004 4:52 PM
  Subject: [LIP] sleep function - perform activity every 10 seconds


  >
  > Hi,
  >
  > I have a process which needs to perform an activity
  > every 10 seconds - starting from the 10 sec boundary.
  >
  > Excuse my terminology, but this should it make it more clear.
  >
  > time    activity
  > -----------------
  > 12:18   process started
  > 12:19   sleep
  > 12:20   ACTIVITY
  > 12:21   sleep
  > 12:22   sleep
  > .....   .....
  > 12:30   ACTIVITY
  >
  >
  > Easy to understand. Once the process starts, I get the current time.
  > Check if the seconds end in digit zero. If yes - perform activity.
  > sleep 1 second. repeat.
  >
  > Then i begin to think - why should I execute sleep call every
  > second when i know the interval? So after first activity, I
  > modify the sleep interval to 10 seconds. It still works.
  >
  > Questions:
  > * I personally prefer calling sleep every second, than doing it
  >    every 10 seconds. Performance wise - any issues?
  > * Is the sleep call accurate or does any rounding take place?
  >    As the 10 second boundary is imperative and not just the interval
  >    of 10 seconds. i.e. After a sleep call of 10 seconds, am I guaranteed
  >    that i will land on a 10 second boundary assuming a start at such a
  >    boundary and that the process needs to be run indefinitely.
  >
  > I hope I'm clear enough. :-)
  >
  > --
  > Rohan
  >
  >
  >
  >
  >
  >
  >
  >



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