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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aJxlvMFD2hHaKdoK@arm.com>
Date: Wed, 13 Aug 2025 12:15:24 +0200
From: Beata Michalska <beata.michalska@....com>
To: Prashant Malani <pmalani@...gle.com>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Jie Zhan <zhanjie9@...ilicon.com>,
	Ionela Voinescu <ionela.voinescu@....com>,
	Ben Segall <bsegall@...gle.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>,
	Mel Gorman <mgorman@...e.de>, Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Valentin Schneider <vschneid@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	z00813676 <zhenglifeng1@...wei.com>, sudeep.holla@....com
Subject: Re: [PATCH v2 2/2] cpufreq: CPPC: Dont read counters for idle CPUs

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