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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael Wysocki" <rjw@rjwysocki.net>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Russell King" <linux@armlinux.org.uk>,
	"David S. Miller" <davem@davemloft.net>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	linux-pm@vger.kernel.org,
	"Vincent Guittot" <vincent.guittot@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
	kvm@vger.kernel.org
Subject: Re: [PATCH V3] cpufreq: Call transition notifier only once for each policy
Date: Fri, 22 Mar 2019 11:57:44 +0530	[thread overview]
Message-ID: <20190322062744.efpl4itnqtny7txf@vireshk-i7> (raw)
In-Reply-To: <alpine.DEB.2.21.1903211645100.1784@nanos.tec.linutronix.de>

On 21-03-19, 16:49, Thomas Gleixner wrote:
> On Wed, 20 Mar 2019, Viresh Kumar wrote:
> >
> > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> > index 3fae23834069..b2fe665878f7 100644
> > --- a/arch/x86/kernel/tsc.c
> > +++ b/arch/x86/kernel/tsc.c
> > @@ -958,10 +958,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> >  	struct cpufreq_freqs *freq = data;
> >  	unsigned long *lpj;
> >  
> > +	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1)) {
> > +		mark_tsc_unstable("cpufreq changes: related CPUs affected");
> > +		return 0;
> > +	}
> 
> You might add a check which ensures that policy->cpu == smp_processor_id()
> because if this is not the case ....

How about something like this ?

	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1 ||
                         freq->policy->cpu != smp_processor_id())) {
		mark_tsc_unstable("cpufreq changes: related CPUs affected");
		return 0;
	}


Thanks for your feedback.

-- 
viresh

WARNING: multiple messages have this Message-ID (diff)
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael Wysocki" <rjw@rjwysocki.net>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Russell King" <linux@armlinux.org.uk>,
	"David S. Miller" <davem@davemloft.net>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	linux-pm@vger.kernel.org,
	"Vincent Guittot" <vincent.guittot@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
	kvm@vger.kernel.org
Subject: Re: [PATCH V3] cpufreq: Call transition notifier only once for each policy
Date: Fri, 22 Mar 2019 06:39:44 +0000	[thread overview]
Message-ID: <20190322062744.efpl4itnqtny7txf@vireshk-i7> (raw)
In-Reply-To: <alpine.DEB.2.21.1903211645100.1784@nanos.tec.linutronix.de>

On 21-03-19, 16:49, Thomas Gleixner wrote:
> On Wed, 20 Mar 2019, Viresh Kumar wrote:
> >
> > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> > index 3fae23834069..b2fe665878f7 100644
> > --- a/arch/x86/kernel/tsc.c
> > +++ b/arch/x86/kernel/tsc.c
> > @@ -958,10 +958,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> >  	struct cpufreq_freqs *freq = data;
> >  	unsigned long *lpj;
> >  
> > +	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1)) {
> > +		mark_tsc_unstable("cpufreq changes: related CPUs affected");
> > +		return 0;
> > +	}
> 
> You might add a check which ensures that policy->cpu = smp_processor_id()
> because if this is not the case ....

How about something like this ?

	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1 ||
                         freq->policy->cpu != smp_processor_id())) {
		mark_tsc_unstable("cpufreq changes: related CPUs affected");
		return 0;
	}


Thanks for your feedback.

-- 
viresh

WARNING: multiple messages have this Message-ID (diff)
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Vincent Guittot" <vincent.guittot@linaro.org>,
	kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	linux-pm@vger.kernel.org, x86@kernel.org,
	"Rafael Wysocki" <rjw@rjwysocki.net>,
	"Russell King" <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, "Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	sparclinux@vger.kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V3] cpufreq: Call transition notifier only once for each policy
Date: Fri, 22 Mar 2019 11:57:44 +0530	[thread overview]
Message-ID: <20190322062744.efpl4itnqtny7txf@vireshk-i7> (raw)
In-Reply-To: <alpine.DEB.2.21.1903211645100.1784@nanos.tec.linutronix.de>

On 21-03-19, 16:49, Thomas Gleixner wrote:
> On Wed, 20 Mar 2019, Viresh Kumar wrote:
> >
> > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> > index 3fae23834069..b2fe665878f7 100644
> > --- a/arch/x86/kernel/tsc.c
> > +++ b/arch/x86/kernel/tsc.c
> > @@ -958,10 +958,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> >  	struct cpufreq_freqs *freq = data;
> >  	unsigned long *lpj;
> >  
> > +	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1)) {
> > +		mark_tsc_unstable("cpufreq changes: related CPUs affected");
> > +		return 0;
> > +	}
> 
> You might add a check which ensures that policy->cpu == smp_processor_id()
> because if this is not the case ....

How about something like this ?

	if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1 ||
                         freq->policy->cpu != smp_processor_id())) {
		mark_tsc_unstable("cpufreq changes: related CPUs affected");
		return 0;
	}


Thanks for your feedback.

-- 
viresh

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-03-22  6:27 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-20  4:52 [PATCH V3] cpufreq: Call transition notifier only once for each policy Viresh Kumar
2019-03-20  4:52 ` Viresh Kumar
2019-03-20  4:52 ` Viresh Kumar
2019-03-21 11:45 ` Peter Zijlstra
2019-03-21 11:45   ` Peter Zijlstra
2019-03-21 11:45   ` Peter Zijlstra
2019-03-21 11:45   ` Peter Zijlstra
2019-03-22  6:19   ` Viresh Kumar
2019-03-22  6:31     ` Viresh Kumar
2019-03-22  6:19     ` Viresh Kumar
2019-04-24  6:47     ` Viresh Kumar
2019-04-24  6:59       ` Viresh Kumar
2019-04-24  6:47       ` Viresh Kumar
2019-04-24  7:26       ` Rafael J. Wysocki
2019-04-24  7:26         ` Rafael J. Wysocki
2019-04-24  7:26         ` Rafael J. Wysocki
2019-03-21 15:49 ` Thomas Gleixner
2019-03-21 15:49   ` Thomas Gleixner
2019-03-21 15:49   ` Thomas Gleixner
2019-03-22  6:27   ` Viresh Kumar [this message]
2019-03-22  6:39     ` Viresh Kumar
2019-03-22  6:27     ` Viresh Kumar
2019-03-22  9:55     ` Rafael J. Wysocki
2019-03-22  9:55       ` Rafael J. Wysocki
2019-03-22  9:55       ` Rafael J. Wysocki

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