Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v2 clocksource 6/7] clocksource: Verify HPET and PMTMR when TSC unverified | Date | Thu, 02 Feb 2023 08:57:39 +0100 |
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On Wed, Feb 01 2023 at 22:40, Waiman Long wrote: > On 2/1/23 14:55, Paul E. McKenney wrote: >>>>> Therefore, when watchdog verification of TSC is disabled, enable it for >>>>> HPET and PMTMR (AKA ACPI PM timer). This provides the needed in-kernel >>>>> time-skew diagnostic without degrading the system's performance. >>>> I'm more than unhappy about this. We finally have a point where the TSC >>>> watchdog overhead can go away without adding TSC=reliable to the kernel >>>> commandline. >>>> >>>> Now you add an unconditionally enforce the watchdog again in a way which >>>> even cannot be disabled on the kernel command line. >>>> >>>> Patently bad idea, no cookies for you! >>> I have a similar concern about this patch as well. That is why I was >>> suggesting to have this enabled for a limited time after boot for sanity >>> checking purpose only. >> Fair enough! >> >> If the watchdog checking of HPET and/or PMTMR against TSC only happens >> only when the sysadm asks for it, would you still want to have the ability >> to enable such watchdog checking at boot time, and then to disable it >> once the system had been running for some limited time? > > Yes, being optional is another way to avoid the overhead for the > majority of users. The paranoids can turn it on if they want to.
Yes, opt-in is good enough.
Thanks,
tglx
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