Re: [PATCH] tools/power turbostat: Allow execution to continue after perf_l2_init() failure

[David Arcari]

Hi Len,

On 4/10/26 8:59 AM, Len Brown wrote:
> Thank you for the patch, David, it is helpful.
>
> I agree that turbostat should do its best to run properly when the
> underlying kernel
> doesn't have full support, and you found a configuration that I missed.
>
> I'd like to understand how/why your kernel perf support is failing on alder lake
> to be sure turbostat is coping the best it can.
>
> If you can identify an upstream kernel version that fails this way,
> that would be great.

I'm using a Fedora kernel:

vmlinuz-7.0.0-0.rc4.260320g0e4f8f1a3d08.40.eln155.x86_64

And turbostat is:

# turbostat -v
turbostat version 2026.02.14 - Len Brown <lenb@xxxxxxxxxx>

> You can poke with "perf stat" as well, but this will depend on what
> .json counter list is compiled into
> your version of perf.
>
> probably a first sanity check would be if these commands for the LLC
> and the L2 work:
>
> sudo perf stat -e cache-misses sleep 1
> sudo perf stat -e L2_REQUEST.ALL sleep 1

# sudo perf stat -e cache-misses sleep 1

 Performance counter stats for 'sleep 1':

   <not supported>      cpu_atom/cache-misses/ 

            11,212      cpu_core/cache-misses/ 


       1.001044852 seconds time elapsed

       0.000793000 seconds user
       0.000000000 seconds sys

# sudo perf stat -e L2_REQUEST.ALL sleep 1

 Performance counter stats for 'sleep 1':

   <not supported>      cpu_atom/L2_REQUEST.ALL/ 

            98,451      cpu_core/L2_REQUEST.ALL/ 


       1.001072723 seconds time elapsed

       0.000761000 seconds user
       0.000000000 seconds sys

> Also, with your L2 patch applied, does turbostat still successfully
> show the LLC stats?
# ./turbostat --quiet -s Core,CPU,LLCMRPS,LLC%hit -n 1
Core	CPU	LLCMRPS	LLC%hit
-	-	1	91.33
0	0	0	93.48
0	1	0	86.86
1	2	0	90.68
1	3	0	98.61
2	4	0	98.59
2	5	0	98.79
3	6	0	90.86
3	7	0	97.64
4	8	0	97.52
4	9	0	99.33
5	10	0	85.54
5	11	0	90.85

Let me know if you need something else.

Thanks,
-DA

> thanks,
> Len Brown, Intel Open Source Technology Center