9.1 callout behavior

[Adrian Chadd]

Hi,

It sounds like you may have found an interesting test case.

Mav, any ideas?



-adrian


On 21 November 2013 05:20, Bret Ketchum <bcketchum at gmail.com> wrote:
>      I've a callout which runs every 100ms and does a bit of accounting
> using the global ticks variable. This one-shot callout was called fairly
> consistently in 8.1, every 100ms give or take a few thousand clocks. I've
> recently upgraded to 9.1 and for the most part the period is consistent.
> However, periodically the callout function is executed anywhere between 5ms
> to 20ms after the callout was reset and the function returned while global
> ticks has increased 8x. The hardware has not changed (using the same
> timecounter configuration):
>
> CPU: Intel(R) Xeon(R) CPU E5-2640 0 @ 2.50GHz (2500.05-MHz K8-class CPU)
>
> kern.timecounter.hardware: TSC-low
> kern.timecounter.tick: 1
> kern.timecounter.invariant_tsc: 1
> kern.timecounter.smp_tsc: 1
>
>      And default eventtimer configuration:
>
> kern.eventtimer.singlemul: 2
> kern.eventtimer.idletick: 0
> kern.eventtimer.activetick: 1
> kern.eventtimer.timer: LAPIC
> kern.eventtimer.periodic: 0
>
>     If tickless mode is disabled the inconsistency goes away. Is the
> premature expiration of the callout expected? Is the jump in global ticks
> typical (say from 100 ticks to 800 ticks in 1.5ms)?
>
>     Bret
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