Re: [PATCH v2 2/2] cpufreq: CPPC: Dont read counters for idle CPUs

[Beata Michalska <beata.michalska@arm.com>]

On Fri, Aug 08, 2025 at 02:14:39AM +0000, Prashant Malani wrote:
> Hi Beata,
> 
> On Aug 07 12:24, Beata Michalska wrote:
> > Right .... that's what happens when you are (I am) making last minute clean up.
> > That should fix it. Would you mind giving it another go ? Would appreciate it.
> > 
> > ---
> > BR
> > Beata
> > 
> > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> > index 65adb78a9a87..2a51e93fcd6c 100644
> > --- a/arch/arm64/kernel/topology.c
> > +++ b/arch/arm64/kernel/topology.c
> > @@ -543,7 +543,7 @@ void counters_burst_read_on_cpu(void *arg)
> >  
> >  static inline bool cpc_reg_supported(struct cpc_reg *reg)
> >  {
> > -       return !((u64)reg->address != 0x0 || (u64)reg->address != 0x1);
> > +       return !((u64)reg->address != 0x0 && (u64)reg->address != 0x1);
> >  }
> 
> Here are the measurements with the fix:
> 
> The readings are less accurate. There are some which report
> 3.4 GHz (as earlier) but many are off:
> 
> t0: del:77500009084, ref:22804739600
> t1: del:77500020316, ref:22804743100
> ref_perf:10
> delivered_perf:32
> 
> t0: del:77910203848, ref:22941794740
> t1: del:77910215594, ref:22941798070
> ref_perf:10
> delivered_perf:35
> 
> t0: del:77354782419, ref:22762276000
> t1: del:77354793991, ref:22762279400
> ref_perf:10
> delivered_perf:34
> 
> t0: del:64470686034, ref:22998377620
> t1: del:64470695313, ref:22998380880
> ref_perf:10
> delivered_perf:28
> 
> t0: del:78019898424, ref:22957940640
> t1: del:78019912872, ref:22957944590
> ref_perf:10
> delivered_perf:36
> 
> Best regards,
> 
> -Prashant
Ok, that's not really good.
Any chances on sharing which platform are you using ?
Remote debugging tends to be rather painful.

---
(Note: I will be off for couple of days so please bear with me)

BR
Beata