I'm looking forward to this patch is committed.
Because this patch solves my problem about CARP timeout.

IIJ, a company that I am working for, is using carp(4) on VMware ESXi hosts
for VPN and web gateway services.

One is master and the other is backup of carp(4).
Active host sometimes failover to backup when the ESXi host gets high cpu usage.
And also CPU ready of OpenBSD machine seems high average on ESXi monitor.

High CPU ready machine delays sending carp advertisement for 3 or 4 seconds.
It is enough to failover to backup.

In my investigation, OpenBSD machine does not always get CPU under high CPU 
ready condition.
Although it is needed for interrupt handler.
The delay of calling hardclock() causes tick count up delay.
One delay is small but will never be resolved.
So total delay can reach 3 or 4 seconds while tick counts up to 100.
The tickless patch can solve the delay.

I have tried to adapt in_carp.c to the tickless attempt 2.
Delay of carp advertisement reduced to about 2 seconds.

> 2020/09/09 4:00、Mark Kettenis <mark.kette...@xs4all.nl>のメール:
> The diff looks reasonable to me, but I'd like to discuss the path
> forward with some people during the hackathon next week.

Is there any discussion in the hackathon?

Yuichiro NAITO

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