From: Peter Zijlstra <peterz@infradead.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael Wysocki" <rjw@rjwysocki.net>,
"Russell King" <linux@armlinux.org.uk>,
"David S. Miller" <davem@davemloft.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"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 V2] cpufreq: Call transition notifier only once for each policy
Date: Fri, 15 Mar 2019 13:29:52 +0100 [thread overview]
Message-ID: <20190315122952.GF6058@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <e2b56be446eeb67f1905d2ac6f8d82dd4389d0c5.1552640968.git.viresh.kumar@linaro.org>
On Fri, Mar 15, 2019 at 02:43:07PM +0530, Viresh Kumar wrote:
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 3fae23834069..cff8779fc0d2 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -956,28 +956,38 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> void *data)
> {
> struct cpufreq_freqs *freq = data;
> - unsigned long *lpj;
> -
> - lpj = &boot_cpu_data.loops_per_jiffy;
> -#ifdef CONFIG_SMP
> - if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> - lpj = &cpu_data(freq->cpu).loops_per_jiffy;
> -#endif
> + struct cpumask *cpus = freq->policy->cpus;
> + bool boot_cpu = !IS_ENABLED(CONFIG_SMP) || freq->flags & CPUFREQ_CONST_LOOPS;
> + unsigned long lpj;
> + int cpu;
>
> if (!ref_freq) {
> ref_freq = freq->old;
> - loops_per_jiffy_ref = *lpj;
> tsc_khz_ref = tsc_khz;
> +
> + if (boot_cpu)
> + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
> + else
> + loops_per_jiffy_ref = cpu_data(cpumask_first(cpus)).loops_per_jiffy;
> }
> +
> if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
> (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
> - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> -
> + lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
> +
> if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> mark_tsc_unstable("cpufreq changes");
>
> - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc());
> + if (boot_cpu) {
> + boot_cpu_data.loops_per_jiffy = lpj;
> + } else {
> + for_each_cpu(cpu, cpus)
> + cpu_data(cpu).loops_per_jiffy = lpj;
> + }
> +
> + for_each_cpu(cpu, cpus)
> + set_cyc2ns_scale(tsc_khz, cpu, rdtsc());
This code doesn't make sense, the rdtsc() _must_ be called on the CPU in
question. That's part of the whole problem here, TSC isn't sync'ed when
it's subject to CPUFREQ.
> }
>
> return 0;
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Vincent Guittot" <vincent.guittot@linaro.org>,
kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
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>,
"Thomas Gleixner" <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V2] cpufreq: Call transition notifier only once for each policy
Date: Fri, 15 Mar 2019 13:29:52 +0100 [thread overview]
Message-ID: <20190315122952.GF6058@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <e2b56be446eeb67f1905d2ac6f8d82dd4389d0c5.1552640968.git.viresh.kumar@linaro.org>
On Fri, Mar 15, 2019 at 02:43:07PM +0530, Viresh Kumar wrote:
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 3fae23834069..cff8779fc0d2 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -956,28 +956,38 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> void *data)
> {
> struct cpufreq_freqs *freq = data;
> - unsigned long *lpj;
> -
> - lpj = &boot_cpu_data.loops_per_jiffy;
> -#ifdef CONFIG_SMP
> - if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> - lpj = &cpu_data(freq->cpu).loops_per_jiffy;
> -#endif
> + struct cpumask *cpus = freq->policy->cpus;
> + bool boot_cpu = !IS_ENABLED(CONFIG_SMP) || freq->flags & CPUFREQ_CONST_LOOPS;
> + unsigned long lpj;
> + int cpu;
>
> if (!ref_freq) {
> ref_freq = freq->old;
> - loops_per_jiffy_ref = *lpj;
> tsc_khz_ref = tsc_khz;
> +
> + if (boot_cpu)
> + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
> + else
> + loops_per_jiffy_ref = cpu_data(cpumask_first(cpus)).loops_per_jiffy;
> }
> +
> if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
> (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
> - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> -
> + lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
> +
> if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> mark_tsc_unstable("cpufreq changes");
>
> - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc());
> + if (boot_cpu) {
> + boot_cpu_data.loops_per_jiffy = lpj;
> + } else {
> + for_each_cpu(cpu, cpus)
> + cpu_data(cpu).loops_per_jiffy = lpj;
> + }
> +
> + for_each_cpu(cpu, cpus)
> + set_cyc2ns_scale(tsc_khz, cpu, rdtsc());
This code doesn't make sense, the rdtsc() _must_ be called on the CPU in
question. That's part of the whole problem here, TSC isn't sync'ed when
it's subject to CPUFREQ.
> }
>
> return 0;
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Vincent Guittot" <vincent.guittot@linaro.org>,
kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
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>,
"Thomas Gleixner" <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V2] cpufreq: Call transition notifier only once for each policy
Date: Fri, 15 Mar 2019 12:29:52 +0000 [thread overview]
Message-ID: <20190315122952.GF6058@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <e2b56be446eeb67f1905d2ac6f8d82dd4389d0c5.1552640968.git.viresh.kumar@linaro.org>
On Fri, Mar 15, 2019 at 02:43:07PM +0530, Viresh Kumar wrote:
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 3fae23834069..cff8779fc0d2 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -956,28 +956,38 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> void *data)
> {
> struct cpufreq_freqs *freq = data;
> - unsigned long *lpj;
> -
> - lpj = &boot_cpu_data.loops_per_jiffy;
> -#ifdef CONFIG_SMP
> - if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> - lpj = &cpu_data(freq->cpu).loops_per_jiffy;
> -#endif
> + struct cpumask *cpus = freq->policy->cpus;
> + bool boot_cpu = !IS_ENABLED(CONFIG_SMP) || freq->flags & CPUFREQ_CONST_LOOPS;
> + unsigned long lpj;
> + int cpu;
>
> if (!ref_freq) {
> ref_freq = freq->old;
> - loops_per_jiffy_ref = *lpj;
> tsc_khz_ref = tsc_khz;
> +
> + if (boot_cpu)
> + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
> + else
> + loops_per_jiffy_ref = cpu_data(cpumask_first(cpus)).loops_per_jiffy;
> }
> +
> if ((val = CPUFREQ_PRECHANGE && freq->old < freq->new) ||
> (val = CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
> - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> -
> + lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
> +
> if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> mark_tsc_unstable("cpufreq changes");
>
> - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc());
> + if (boot_cpu) {
> + boot_cpu_data.loops_per_jiffy = lpj;
> + } else {
> + for_each_cpu(cpu, cpus)
> + cpu_data(cpu).loops_per_jiffy = lpj;
> + }
> +
> + for_each_cpu(cpu, cpus)
> + set_cyc2ns_scale(tsc_khz, cpu, rdtsc());
This code doesn't make sense, the rdtsc() _must_ be called on the CPU in
question. That's part of the whole problem here, TSC isn't sync'ed when
it's subject to CPUFREQ.
> }
>
> return 0;
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Vincent Guittot" <vincent.guittot@linaro.org>,
kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
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>,
"Thomas Gleixner" <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V2] cpufreq: Call transition notifier only once for each policy
Date: Fri, 15 Mar 2019 13:29:52 +0100 [thread overview]
Message-ID: <20190315122952.GF6058@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <e2b56be446eeb67f1905d2ac6f8d82dd4389d0c5.1552640968.git.viresh.kumar@linaro.org>
On Fri, Mar 15, 2019 at 02:43:07PM +0530, Viresh Kumar wrote:
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 3fae23834069..cff8779fc0d2 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -956,28 +956,38 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> void *data)
> {
> struct cpufreq_freqs *freq = data;
> - unsigned long *lpj;
> -
> - lpj = &boot_cpu_data.loops_per_jiffy;
> -#ifdef CONFIG_SMP
> - if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> - lpj = &cpu_data(freq->cpu).loops_per_jiffy;
> -#endif
> + struct cpumask *cpus = freq->policy->cpus;
> + bool boot_cpu = !IS_ENABLED(CONFIG_SMP) || freq->flags & CPUFREQ_CONST_LOOPS;
> + unsigned long lpj;
> + int cpu;
>
> if (!ref_freq) {
> ref_freq = freq->old;
> - loops_per_jiffy_ref = *lpj;
> tsc_khz_ref = tsc_khz;
> +
> + if (boot_cpu)
> + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
> + else
> + loops_per_jiffy_ref = cpu_data(cpumask_first(cpus)).loops_per_jiffy;
> }
> +
> if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
> (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
> - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> -
> + lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
> +
> if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> mark_tsc_unstable("cpufreq changes");
>
> - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc());
> + if (boot_cpu) {
> + boot_cpu_data.loops_per_jiffy = lpj;
> + } else {
> + for_each_cpu(cpu, cpus)
> + cpu_data(cpu).loops_per_jiffy = lpj;
> + }
> +
> + for_each_cpu(cpu, cpus)
> + set_cyc2ns_scale(tsc_khz, cpu, rdtsc());
This code doesn't make sense, the rdtsc() _must_ be called on the CPU in
question. That's part of the whole problem here, TSC isn't sync'ed when
it's subject to CPUFREQ.
> }
>
> return 0;
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-15 12:30 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 9:13 [PATCH V2] cpufreq: Call transition notifier only once for each policy Viresh Kumar
2019-03-15 9:25 ` Viresh Kumar
2019-03-15 9:13 ` Viresh Kumar
2019-03-15 9:13 ` Viresh Kumar
2019-03-15 12:29 ` Peter Zijlstra [this message]
2019-03-15 12:29 ` Peter Zijlstra
2019-03-15 12:29 ` Peter Zijlstra
2019-03-15 12:29 ` Peter Zijlstra
2019-03-18 2:35 ` Viresh Kumar
2019-03-18 2:47 ` Viresh Kumar
2019-03-18 2:35 ` Viresh Kumar
2019-03-18 10:53 ` Peter Zijlstra
2019-03-18 10:53 ` Peter Zijlstra
2019-03-18 10:53 ` Peter Zijlstra
2019-03-18 10:53 ` Peter Zijlstra
2019-03-18 11:09 ` Rafael J. Wysocki
2019-03-18 11:09 ` Rafael J. Wysocki
2019-03-18 11:09 ` Rafael J. Wysocki
2019-03-18 11:20 ` Rafael J. Wysocki
2019-03-18 11:20 ` Rafael J. Wysocki
2019-03-18 11:20 ` Rafael J. Wysocki
2019-03-18 10:45 ` Rafael J. Wysocki
2019-03-18 10:45 ` Rafael J. Wysocki
2019-03-18 10:45 ` Rafael J. Wysocki
2019-03-18 11:01 ` Peter Zijlstra
2019-03-18 11:01 ` Peter Zijlstra
2019-03-18 11:01 ` Peter Zijlstra
2019-03-18 11:01 ` Peter Zijlstra
2019-03-18 11:49 ` Rafael J. Wysocki
2019-03-18 11:49 ` Rafael J. Wysocki
2019-03-18 11:49 ` Rafael J. Wysocki
2019-03-19 5:50 ` Viresh Kumar
2019-03-19 5:51 ` Viresh Kumar
2019-03-19 5:50 ` Viresh Kumar
2019-03-19 9:41 ` Rafael J. Wysocki
2019-03-19 9:41 ` Rafael J. Wysocki
2019-03-19 9:41 ` Rafael J. Wysocki
2019-03-19 10:49 ` Viresh Kumar
2019-03-19 10:49 ` Viresh Kumar
2019-03-19 10:49 ` Viresh Kumar
2019-03-19 15:44 ` Rafael J. Wysocki
2019-03-19 15:44 ` Rafael J. Wysocki
2019-03-19 15:44 ` Rafael J. Wysocki
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