Re: [PATCH 0/2] Fix TSC issues on (some) AMD Ryzen based systems

[Paul Menzel]

Dear Jan,


Am 29.01.19 um 20:33 schrieb Paul Menzel:

> Thank you for adding me to the CC list.
>
>
> Am 29.01.19 um 11:23 schrieb Jan H. SchÃnherr:
> > My newly acquired AMD Ryzen Threadripper based system seems to have
> > some TSC quirks, which go away once the system is up.
> >
> > Given the discussion in https://lkml.org/lkml/2019/1/28/1356
> > I don't seem to be the only one, and it does not seem to be
> > Threadripper specific.
> >
> > The first patch addresses presumably SMI interruptions, that occur
> > on my system at a 60 Hz frequency. They take too long, making the
> > existing code fail. The patch makes that code more resilient.
> > (These interruptions go away at some point during boot; also proven
> > by the fact, that I don't have any TSC issues, when kexecing into
> > a new kernel.)
> >
> > The second patch prevents TSC going unstable when resuming from S3.
> > This may have a similar source, but is certainly more weird: the
> > TSC is observed to go backwards on CPU0 by about 200 to 500 cycles
> > compared to other CPUs every once in a while, as long as its sibling
> > (CPU16 in my case) hasn't been resumed yet. (I did some experiments
> > with CPU hotplug before and after suspend, but apart from reproducing
> > the issue and verifying the "fix", I got nowhere.)
> >
> > The patches are against v4.20.
> >
> > Jan H. SchÃnherr (2):
> > ÂÂ x86/tsc: Allow quick PIT calibration despite interruptions
> > ÂÂ cpu/hotplug: Unfreeze sibling CPU first on resume from S3
> >
> > Â arch/x86/kernel/tsc.c | 80 +++++++++++++++++++++++++------------------
> > Â kernel/cpu.cÂÂÂÂÂÂÂÂÂ | 34 ++++++++++++------
> > Â 2 files changed, 70 insertions(+), 44 deletions(-)
>
> I successfully tested both applied on Linusâ current master branch
> (v5.0-rc4-1-g4aa9fc2a435a).
>
> > [ÂÂÂ 0.000000] DMI: HP HP EliteDesk 705 G4 MT/83E7, BIOS Q06 Ver. 02.04.01 09/14/2018
> > [ÂÂÂ 0.000000] tsc: Fast TSC calibration using PIT
> > [ÂÂÂ 0.000000] tsc: Detected 3616.864 MHz processor

Please do not forget to tag both patches for the stable releases
by adding the tag.

> CC: stable@xxxxxxxxxxxxxxx


Kind regards,

Paul