Re: [PATCH v4 2/4] pps: Drop the !NO_HZ_COMMON dependency from NTP_PPS

From: Rodolfo Giometti

Date: Tue Sep 29 2026 - 02:39:32 EST


On Mon, 2026-09-28 at 20:28 +0100, David Woodhouse wrote:
Yeah, working on that now. My first soak test on the nohz_full build
didn't have nohz_idle, so it wasn't really very tickless.
[...]
More data, and pretty graphs, when I'm confident of the results and have the
A/B testing.

Thanks, looking forward to it.

For the A/B comparison, could you also report the hardpps side, i.e.
the PPS offset, jitter and stability as returned by adjtimex(), on
both the tickful and the tickless kernel? ntp_error shows that the
correction works; those show whether the PPS discipline converges as
well as it does today, which is what 2/4 is about.

Please also state whether the pulse comes from a real GPS on a GPIO
or from the vmclock 1PPS in 4/4.

The ntp_error being corrected is still two orders of magnitude less
than the jitter on the IRQ, mind you.

Worth a sentence in the commit message too, I think.

Ciao,

Rodolfo