Re: timekeeping regression?

["Mathew, Cherry G.*" <c%bow.st@localhost>]

>>>>> Greg A Woods <woods%planix.ca@localhost> writes:

    > At Sun, 18 Feb 2024 01:40:52 -0800, "Greg A. Woods" <woods%planix.ca@localhost> wrote:
    > Subject: Re: timekeeping regression?
    >> 
    >> Still looking for a Round Tuit to do the investigation into why
    >> "clocksource=tsc" isn't taking effect, and it'll have to wait a
    >> couple more weeks now, so if anyone else beats me to it.....

    > I did some code-reading and added some printk's to the Xen kernel
    > and discovered the reason "clocksource=tsc" didn't work is because
    > none of my Xen machines have X86_FEATURE_TSC_RELIABLE, and when I
    > faked it the "warp" detection check invalidated it anyway.

    > I think I just discovered the difference between the "good" and
    > "bad" machines.  The "good" ones both still had
    > "dom0_vcpus_pin=true".

    > I'll reboot the bad one with that added again soon and see how it
    > does.

This is interesting. I imagine that the current timecounter(9) MD code
doesn't factor in the backing hardware physical CPU being yanked from
under it, assuming that it then relies on the TSC from it, for
timekeeping.

Did you say that this is only relevant for "clocksource=tsc" again ?

-- 
MatC/(~cherry)