Re: Scheduler accounting inflated for io bound processes.

[David Ahern <dsahern@gmail.com>]

On 6/26/13 10:10 AM, Ingo Molnar wrote:
>> Sampled H/W events have an adaptive period that converges to the desired
>> sampling rate. The first few samples come in 10 usecs are so apart and
>> the time period expands to the desired rate. As I recall that adaptive
>> algorithm starts over every time the event is scheduled in.
>
> Yes, but last I checked it (2 years ago? :-) the auto-freq code was
> converging pretty well to the time clock, with little jitter - in essence
> turning it into a fixed-period, fixed-frequency sampling method. That
> would explain Mike's results.

It does converge quickly and stay there for CPU-based events. My point 
was more along the lines that the code is there. Perhaps a tweak to add 
jitter to the period would address fixed period sampling affects.

David