> Date: Mon, 14 Aug 2017 16:06:51 -0400
> From: Martin Pieuchot <[email protected]>
>
> I'd like to improve the fairness of the scheduler, with the goal of
> mitigating userland starvations. For that the kernel needs to have
> a better understanding of the amount of executed time per task.
>
> The smallest interval currently usable on all our architectures for
> such accounting is a tick. With the current HZ value of 100, this
> smallest interval is 10ms. I'd like to bump this value to 1000.
>
> The diff below intentionally bump other `hz' value to keep current
> ratios. We certainly want to call schedclock(), or a similar time
> accounting function, at a higher frequency than 16 Hz. However this
> will be part of a later diff.
>
> I'd be really interested in test reports. mlarkin@ raised a good
> question: is your battery lifetime shorter with this diff?
>
> Comments, oks?
Need to look at this a bit more carefully but:
> Index: conf/param.c
> ===================================================================
> RCS file: /cvs/src/sys/conf/param.c,v
> retrieving revision 1.37
> diff -u -p -r1.37 param.c
> --- conf/param.c 6 May 2016 19:45:35 -0000 1.37
> +++ conf/param.c 14 Aug 2017 17:03:23 -0000
> @@ -76,7 +76,7 @@
> # define DST 0
> #endif
> #ifndef HZ
> -#define HZ 100
> +#define HZ 1000
> #endif
> int hz = HZ;
> int tick = 1000000 / HZ;
> Index: kern/kern_clock.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_clock.c,v
> retrieving revision 1.93
> diff -u -p -r1.93 kern_clock.c
> --- kern/kern_clock.c 22 Jul 2017 14:33:45 -0000 1.93
> +++ kern/kern_clock.c 14 Aug 2017 19:50:49 -0000
> @@ -406,12 +406,11 @@ statclock(struct clockframe *frame)
> if (p != NULL) {
> p->p_cpticks++;
> /*
> - * If no schedclock is provided, call it here at ~~12-25 Hz;
> + * If no schedclock is provided, call it here;
> * ~~16 Hz is best
> */
> if (schedhz == 0) {
> - if ((++curcpu()->ci_schedstate.spc_schedticks & 3) ==
> - 0)
> + if ((spc->spc_schedticks & 0x3f) == 0)
That ++ should not be dropped sould it?
