>> Just how would you do kernel/user CPU time accounting then ?
>> It's currently done on every timer tick, and doing it less
>> often would make it useless.
>
> Except for machines with very slow timers we really should account time
> to processes during context switch instead of sampling on timer ticks.
> The current values are in many situations (i.e., lots of processes
> or a process frequently waiting for events bound to timer) a pile
> of random numbers.
Linux should maintain some sort of per-process decaying average.
This data is required for a Unix98-compliant ps program. (for %CPU)
Currently ps is using total CPU usage over the life of the process.
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