Re: [PATCHv2] timekeeping: Update multiplier when NTP frequency is set directly

From: John Stultz
Date: Fri Jun 22 2018 - 17:12:35 EST


On Fri, Jun 22, 2018 at 2:09 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> On Mon, 4 Jun 2018, Miroslav Lichvar wrote:
>
>> When the NTP frequency is set directly from userspace using the
>> ADJ_FREQUENCY or ADJ_TICK timex mode, immediately update the
>> timekeeper's multiplier instead of waiting for the next tick.
>>
>> This removes a hidden non-deterministic delay in setting of the
>> frequency and allows an extremely tight control of the system clock
>> with update rates close to or even exceeding the kernel HZ.
>>
>> The update is limited to archs using modern timekeeping
>> (!ARCH_USES_GETTIMEOFFSET).
>
> John ?????

Yea. I've got this in my toqueue list. I'm going to take another pass
at testing and hopefully send it your way.

thanks
-john