Re: [PATCH 3/3] tools/power turbostat: allow turbostat to work when aperf is not available

[David Arcari]

On 11/25/25 2:14 PM, Len Brown wrote:
> It would be helpful if you could describe exactly what environment you
> are running in.

It' a VMWARE instance.

CPUID(0): AuthenticAMD 0xd CPUID levels
CPUID(1): family:model:stepping 0x17:0:0 (23:0:0) microcode 0x0
CPUID(0x80000000): max_extended_levels: 0x8000001f
CPUID(1): SSE3 - - - - TSC MSR - - -
CPUID(6): No-APERF, No-TURBO, No-DTS, No-PTM, No-HWP, No-HWPnotify, 
No-HWPwindow, No-HWPepp, No-HWPpkg, No-EPB
CPUID(7): No-SGX No-Hybrid


> are there any MSRs?

I'm not certain, is there something in particular you are looking for?

> Is APERF available via perf, but not via MSR?
> etc.

I don't believe that APERF was available via perf. I'll go back and 
verify when I have a chance.

-DA

> On Tue, Nov 18, 2025 at 10:58 AM David Arcari <darcari@xxxxxxxxxx> wrote:
> > Currently when aperf is not available the function has_amperf() still
> > returns true.  The end result is that the program gets an error in
> > delta_thread() which causes turbostat to restart.  We can avoid this
> > by not setting msr_counter_arch_infos[MSR_ARCH_INFO_APERF_INDEX].present
> > when aperf is not available allowing turbostat to execute normally.
> >
> > Signed-off-by: David Arcari <darcari@xxxxxxxxxx>
> > Cc: Len Brown <lenb@xxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >   tools/power/x86/turbostat/turbostat.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
> > index 5567b9ecd516..b3f1e4ae5813 100644
> > --- a/tools/power/x86/turbostat/turbostat.c
> > +++ b/tools/power/x86/turbostat/turbostat.c
> > @@ -8592,6 +8592,10 @@ void msr_perf_init_(void)
> >                                  continue;
> >
> >                          if (cai->needed) {
> > +                               /* check to see if APERF is available */
> > +                               if (cidx == MSR_ARCH_INFO_APERF_INDEX && !has_aperf)
> > +                                       continue;
> > +
> >                                  /* Use perf API for this counter */
> >                                  if (add_msr_perf_counter(cpu, cci, cai) != -1) {
> >                                          cci->source[cai->rci_index] = COUNTER_SOURCE_PERF;
> > --
> > 2.51.0