Re: [patch 5/5] clocksource: Rewrite watchdog code completely
Borislav Petkov <[email protected]>
| Newsgroups | org.kernel.vger.linux-parisc,org.kernel.vger.linux-kernel,org.kernel.vger.linux-mips |
|---|---|
| Message-ID | <20260309154317.GPaa7qlRzYcQY1dBU3@fat_crate.local> |
On Sat, Jan 24, 2026 at 12:18:01AM +0100, Thomas Gleixner wrote: Patch 2 and 4 should say "Don't" in the subject title. :) > The clocksource watchdog code has over time reached the state of an > unpenetrable maze of duct tape and staples. The original design, which was "impenetrable" > made in the context of systems far smaller than today, is based on the > assumption that the to be monitored clocksource (TSC) can be trivially > compared against a known to be stable clocksource (HPET/ACPI-PM timer). > > Over the years it turned out that this approach has major flaws: > > - Long delays between watchdog invocations can result in wrap arounds > of the reference clocksource > > - Scalability of the reference clocksource readout can degrade on large > multi-socket systems due to interconnect congestion > > This was addressed with various heuristics which degraded the accurracy of "accuracy" But those are just nitpicks. The overall thing sounds good to me, I haven't done any indepth review but from a cursory look, it looks nice. Testing looks good too on one machine so Tested-by: Borislav Petkov (AMD) <[email protected]> I say, let's queue it now so that it can get wider testing. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette