powerpc64 head -r344018 stuck sleeping problems: th->th_scale * tc_delta(th) overflows unsigned 64 bits sometimes [patched failed]

[Mark Millard]

On 2019-Mar-1, at 13:11, Ian Lepore <ian at freebsd.org> wrote:

> On Fri, 2019-03-01 at 20:57 +0000, Poul-Henning Kamp wrote:
>> --------
>> In message <679402FF-907C-43AF-B18C-8C9CC857D7A6 at yahoo.com>, Mark
>> Millard via freebsd-hackers writes:
>> 
>>>> I must admit that 2 seconds of interval where the timehands where
>>>> not updated is too much.
>> 
>> I have no idea how you got in that situation, but it is very far
>> from how timecounters were designed to work.
>> 
> 
> I wonder if it's fallout from reducing the number of timehands to 2,
> which always struck me as a really bad idea. I know of at least one arm
> configuration which fails because of it (it takes a combo of a single-
> core system, and a pps capture driver that uses hardware latching of
> the timer and the polling method for reading the latched value; given
> all that, at least 4 sets of timehands are needed to avoid losing PPS
> events due to generation changes).

Thanks for the suggestion.

I tried putting back having 10 timehands structures with my
variant of the original binuptime code. (My investigative
code records some information.) Unfortunately, having the
extra timehands's did not change the PowerMac G5's behavior.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)