On Tue, Nov 16, 2021 at 06:44:22PM -0500, Waiman Long wrote:
A few questions:
1. Once you have all the patches in place, is the increase in
WATCHDOG_MAX_SKEW from 50us to 100us necessary?
I can remove the hunk of changing cs->uncertainty_margin. It is critical for this patch.
2. The reason for having cs->uncertainty_margin set to
2*WATCHDOG_MAX_SKEW was to allow for worst-case skew from both
the previous and the current reading. Are you sure that
dropping back to WATCHDOG_MAX_SKEW avoids false positives?
3. In patch 3/4, shouldn't clock_skew_skip be a field in the
clocksource structure rather than a global? If a system had
multiple clocks being checked, wouldn't having this as a field
make things more predictable? Or am I missing something subtle
Yes, that is my intention.
4. These are intended to replace this commit in -rcu, correct?
9d5739316f36 ("clocksource: Forgive repeated long-latency watchdog clocksource reads")
But not this commit, correct?
5444fb39fd49 ("torture: Test splatting for delay-ridden clocksources")
And would you like me to queue these, or would you rather send them
separately? (Either way works for me, just please let me know.)