From: Peter Zijlstra <peterz@infradead.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>,
x86@kernel.org, jose.souza@intel.com, hpa@zytor.com,
bp@alien8.de, mingo@redhat.com, tglx@linutronix.de,
kai.heng.feng@canonical.com, bhelgaas@google.com,
linux-pci@vger.kernel.org, rudolph@fb.com, xapienz@fb.com,
bmilton@fb.com, stable@vger.kernel.org
Subject: Re: [PATCH] x86/intel: Disable HPET on another Intel Coffee Lake platform
Date: Fri, 17 Sep 2021 11:34:39 +0200 [thread overview]
Message-ID: <YURhL33YyXRMkdC6@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YURb1bzc3L4gNI9Q@hirez.programming.kicks-ass.net>
On Fri, Sep 17, 2021 at 11:11:49AM +0200, Peter Zijlstra wrote:
> On Thu, Sep 16, 2021 at 10:07:07AM -0500, Bjorn Helgaas wrote:
> > This seems to be an ongoing issue, not just a point defect in a single
> > product, and I really hate the onesy-twosy nature of this. Is there
> > really no way to detect this issue automatically or fix whatever Linux
> > bug makes us trip over this? I am no clock expert, so I have
> > absolutely no idea whether this is possible.
>
> X86 is gifted with the grant total of _0_ reliable clocks. Given no
> accurate time, it is impossible to tell which one of them is broken
> worst. Although I suppose we could attempt to synchronize against the
> PMU or MPERF..
>
> We could possibly disable the tsc watchdog for
> X86_FEATURE_TSC_KNOWN_FREQ && X86_FEATURE_TSC_ADJUST I suppose.
>
> And then have people with 'creative' BIOS get to keep the pieces.
Alternatively, we can change what the TSC watchdog does for
X86_FEATURE_TSC_ADJUST machines. Instead of checking time against HPET
it can check if TSC_ADJUST changes. That should make it more resillient
vs HPET time itself being off.
next prev parent reply other threads:[~2021-09-17 9:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 13:17 [PATCH] x86/intel: Disable HPET on another Intel Coffee Lake platform Jakub Kicinski
2021-09-16 15:07 ` Bjorn Helgaas
2021-09-16 15:30 ` Jakub Kicinski
2021-09-16 16:35 ` Paul E. McKenney
2021-09-17 2:57 ` Jakub Kicinski
2021-09-17 3:33 ` Paul E. McKenney
2021-09-17 9:11 ` Peter Zijlstra
2021-09-17 9:34 ` Peter Zijlstra [this message]
2021-09-19 0:14 ` Thomas Gleixner
2021-09-21 18:05 ` Rafael J. Wysocki
2021-09-21 20:18 ` Thomas Gleixner
2021-09-22 20:27 ` Rafael J. Wysocki
2021-09-22 22:21 ` Thomas Gleixner
2021-09-23 10:46 ` Rafael J. Wysocki
2021-09-17 14:00 ` Krzysztof Wilczyński
2021-09-17 14:58 ` Jakub Kicinski
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