Re: Why was the timehands_count sysctl added?

On Sat, Oct 9, 2021, 1:56 PM Konstantin Belousov <kostikbel@gmail.com>
wrote:

> On Sat, Oct 09, 2021 at 09:41:28PM +0200, Sebastian Huber wrote:
> > Hello,
> >
> > I synchronize currently the port of the FreeBSD timecounters to RTEMS and
> > came across a change in 2019 which I do not understand. Some time ago the
> > timehands were reduced from 10 to two:
> >
> > https://reviews.freebsd.org/D7302
> >
> > In 2019 this changed again to be up to 16:
> >
> > https://reviews.freebsd.org/D21563
> This review did not changed it back to 16, the default value is still 2.
> It allows to bump the number of used timehands, but normally systems run
> with only 2.
>
> >
> > The corresponding sysctl is not documented:
> >
> > https://www.freebsd.org/cgi/man.cgi?query=timecounters&sektion=4
> >
> > Does someone know why this sysctl to select the count of timehands was
> > added? Is this a performance optimization for some systems?
>
> To allow for experimentation, and to satisfy some requests where people
> wanted to have more that 2 timehands.
>

When would someone want that? What's the use case?

Warner

>