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

[David Arcari <darcari@redhat.com>]

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@redhat.com> 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@redhat.com>
>> Cc: Len Brown <lenb@kernel.org>
>> Cc: linux-kernel@vger.kernel.org
>> ---
>>   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
>>
>>
> 
>