On Fri, May 29, 2026 at 07:43:48AM -0700, Sean Christopherson wrote: > Don't re-calibrate the TSC frequency if the TSC is known to run at a fixed > frequency. In practice, this is likely one big nop, as re-calibration is > used only for SMP=n kernels, and only for hardware that is 20+ years old, > i.e. is extremely unlikely to collide with TSC_KNOWN_FREQ.
Why do we care? So what if it recalibrates once on UP? Look where it is called - all old rust which no one uses anymore. > Signed-off-by: Sean Christopherson <[email protected]> > --- > arch/x86/kernel/tsc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index c5110eb554bc..08cf6625d484 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -946,7 +946,8 @@ void recalibrate_cpu_khz(void) > return; > > cpu_khz = x86_platform.calibrate_cpu(); > - tsc_khz = x86_platform.calibrate_tsc(); > + if (!boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) cpu_feature_enabled() everywhere please. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
