Currently, when the CPU frequency is stale the nominal clock frequency
is returned by calls to arch_freq_get_on_cpu(). Some users are
confused by the high reported frequency when their system is idle
and/or it is above a reduced maximum they set.
This patch will return the policy minimum as the stale frequency reply
from arch_freq_get_on_cpu().
Reported-by: Yang Jie <[email protected]>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217597
Signed-off-by: Doug Smythies <[email protected]>
---
arch/x86/kernel/cpu/aperfmperf.c | 13 +++++--------
drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++
include/linux/cpufreq.h | 5 +++++
3 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index fdbb5f07448f..44cc96864d94 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -418,9 +418,10 @@ unsigned int arch_freq_get_on_cpu(int cpu)
unsigned long last;
u64 acnt, mcnt;
- if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
- goto fallback;
-
+ if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)){
+ freq = cpufreq_quick_get(cpu);
+ return freq ? freq : cpufreq_quick_get_min(cpu);
+ }
do {
seq = raw_read_seqcount_begin(&s->seq);
last = s->last_update;
@@ -433,13 +434,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
* which covers idle and NOHZ full CPUs.
*/
if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
- goto fallback;
+ return cpufreq_quick_get_min(cpu);
return div64_u64((cpu_khz * acnt), mcnt);
-
-fallback:
- freq = cpufreq_quick_get(cpu);
- return freq ? freq : cpu_khz;
}
static int __init bp_init_aperfmperf(void)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 50bbc969ffe5..a0b24f61a5b0 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1796,6 +1796,24 @@ unsigned int cpufreq_quick_get_max(unsigned int cpu)
}
EXPORT_SYMBOL(cpufreq_quick_get_max);
+/**
+ * cpufreq_quick_get_min - return the min frequency for a given CPU
+ * @cpu: CPU number
+ */
+unsigned int cpufreq_quick_get_min(unsigned int cpu)
+{
+ struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+ unsigned int ret_freq = 0;
+
+ if (policy) {
+ ret_freq = policy->min;
+ cpufreq_cpu_put(policy);
+ }
+
+ return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_quick_get_min);
+
/**
* cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU
* @cpu: CPU number
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 172ff51c1b2a..c74dcb5f9263 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -220,6 +220,7 @@ static inline bool policy_is_shared(struct cpufreq_policy *policy)
unsigned int cpufreq_get(unsigned int cpu);
unsigned int cpufreq_quick_get(unsigned int cpu);
unsigned int cpufreq_quick_get_max(unsigned int cpu);
+unsigned int cpufreq_quick_get_min(unsigned int cpu);
unsigned int cpufreq_get_hw_max_freq(unsigned int cpu);
void disable_cpufreq(void);
@@ -250,6 +251,10 @@ static inline unsigned int cpufreq_quick_get_max(unsigned int cpu)
{
return 0;
}
+static inline unsigned int cpufreq_quick_get_min(unsigned int cpu)
+{
+ return 0;
+}
static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
{
return 0;
--
2.25.1
On Tue, Jul 25, 2023 at 2:14 AM Doug Smythies <[email protected]> wrote:
>
> Currently, when the CPU frequency is stale the nominal clock frequency
> is returned by calls to arch_freq_get_on_cpu(). Some users are
> confused by the high reported frequency when their system is idle
> and/or it is above a reduced maximum they set.
>
> This patch will return the policy minimum as the stale frequency reply
> from arch_freq_get_on_cpu().
>
> Reported-by: Yang Jie <[email protected]>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217597
> Signed-off-by: Doug Smythies <[email protected]>
> ---
> arch/x86/kernel/cpu/aperfmperf.c | 13 +++++--------
> drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++
> include/linux/cpufreq.h | 5 +++++
> 3 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
> index fdbb5f07448f..44cc96864d94 100644
> --- a/arch/x86/kernel/cpu/aperfmperf.c
> +++ b/arch/x86/kernel/cpu/aperfmperf.c
> @@ -418,9 +418,10 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> unsigned long last;
> u64 acnt, mcnt;
>
> - if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> - goto fallback;
> -
> + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)){
> + freq = cpufreq_quick_get(cpu);
> + return freq ? freq : cpufreq_quick_get_min(cpu);
> + }
> do {
> seq = raw_read_seqcount_begin(&s->seq);
> last = s->last_update;
> @@ -433,13 +434,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> * which covers idle and NOHZ full CPUs.
> */
> if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
> - goto fallback;
> + return cpufreq_quick_get_min(cpu);
>
> return div64_u64((cpu_khz * acnt), mcnt);
> -
> -fallback:
> - freq = cpufreq_quick_get(cpu);
> - return freq ? freq : cpu_khz;
It looks to me like modifying cpufreq_quick_get) to return policy->min
if policy->cur is 0 would work in a similar way, wouldn't it?
> }
>
> static int __init bp_init_aperfmperf(void)
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 50bbc969ffe5..a0b24f61a5b0 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1796,6 +1796,24 @@ unsigned int cpufreq_quick_get_max(unsigned int cpu)
> }
> EXPORT_SYMBOL(cpufreq_quick_get_max);
>
> +/**
> + * cpufreq_quick_get_min - return the min frequency for a given CPU
> + * @cpu: CPU number
> + */
> +unsigned int cpufreq_quick_get_min(unsigned int cpu)
> +{
> + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> + unsigned int ret_freq = 0;
> +
> + if (policy) {
> + ret_freq = policy->min;
> + cpufreq_cpu_put(policy);
> + }
> +
> + return ret_freq;
> +}
> +EXPORT_SYMBOL(cpufreq_quick_get_min);
> +
> /**
> * cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU
> * @cpu: CPU number
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 172ff51c1b2a..c74dcb5f9263 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -220,6 +220,7 @@ static inline bool policy_is_shared(struct cpufreq_policy *policy)
> unsigned int cpufreq_get(unsigned int cpu);
> unsigned int cpufreq_quick_get(unsigned int cpu);
> unsigned int cpufreq_quick_get_max(unsigned int cpu);
> +unsigned int cpufreq_quick_get_min(unsigned int cpu);
> unsigned int cpufreq_get_hw_max_freq(unsigned int cpu);
> void disable_cpufreq(void);
>
> @@ -250,6 +251,10 @@ static inline unsigned int cpufreq_quick_get_max(unsigned int cpu)
> {
> return 0;
> }
> +static inline unsigned int cpufreq_quick_get_min(unsigned int cpu)
> +{
> + return 0;
> +}
> static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
> {
> return 0;
> --
> 2.25.1
>
>
Hi Rafael,
On Tue, Jul 25, 2023 at 11:31 AM Rafael J. Wysocki <[email protected]> wrote:
> On Tue, Jul 25, 2023 at 2:14 AM Doug Smythies <[email protected]> wrote:
> >
> > Currently, when the CPU frequency is stale the nominal clock frequency
> > is returned by calls to arch_freq_get_on_cpu(). Some users are
> > confused by the high reported frequency when their system is idle
> > and/or it is above a reduced maximum they set.
> >
> > This patch will return the policy minimum as the stale frequency reply
> > from arch_freq_get_on_cpu().
> >
> > Reported-by: Yang Jie <[email protected]>
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217597
> > Signed-off-by: Doug Smythies <[email protected]>
> > ---
> > arch/x86/kernel/cpu/aperfmperf.c | 13 +++++--------
> > drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++
> > include/linux/cpufreq.h | 5 +++++
> > 3 files changed, 28 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
> > index fdbb5f07448f..44cc96864d94 100644
> > --- a/arch/x86/kernel/cpu/aperfmperf.c
> > +++ b/arch/x86/kernel/cpu/aperfmperf.c
> > @@ -418,9 +418,10 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > unsigned long last;
> > u64 acnt, mcnt;
> >
> > - if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> > - goto fallback;
> > -
> > + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)){
> > + freq = cpufreq_quick_get(cpu);
> > + return freq ? freq : cpufreq_quick_get_min(cpu);
> > + }
> > do {
> > seq = raw_read_seqcount_begin(&s->seq);
> > last = s->last_update;
> > @@ -433,13 +434,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > * which covers idle and NOHZ full CPUs.
> > */
> > if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
> > - goto fallback;
> > + return cpufreq_quick_get_min(cpu);
> >
> > return div64_u64((cpu_khz * acnt), mcnt);
> > -
> > -fallback:
> > - freq = cpufreq_quick_get(cpu);
> > - return freq ? freq : cpu_khz;
>
> It looks to me like modifying cpufreq_quick_get) to return policy->min
> if policy->cur is 0 would work in a similar way, wouldn't it?
For the configuration of intel_cpufreq driver (intel_pstate in
passive mode), schedutil governor, HWP enabled, for
a stale frequency policy->cur is not 0 and will always
be whatever the min value was when the driver was initialized,
regardless of what has been set since.
The patch I submitted deals with that situation also.
A complete list of driver/governor/HWP stale frequency
replies can be found on the bugzilla report at:
https://bugzilla.kernel.org/attachment.cgi?id=304694
There might be push back on some of the performance
governor stale frequency replies. I could not figure out
a performance governor dependant reply.
Also there are other callers to cpufreq_quick_get
and I was not sure I could mess with the function
response for them. For example
drivers/devfreq/tegra30-devfreq.c
and drivers/thermal/cpufreq_cooling.c
and drivers/powercap/dtpm_cpu.c
>
> > }
> >
> > static int __init bp_init_aperfmperf(void)
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index 50bbc969ffe5..a0b24f61a5b0 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -1796,6 +1796,24 @@ unsigned int cpufreq_quick_get_max(unsigned int cpu)
> > }
> > EXPORT_SYMBOL(cpufreq_quick_get_max);
> >
> > +/**
> > + * cpufreq_quick_get_min - return the min frequency for a given CPU
> > + * @cpu: CPU number
> > + */
> > +unsigned int cpufreq_quick_get_min(unsigned int cpu)
> > +{
> > + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> > + unsigned int ret_freq = 0;
> > +
> > + if (policy) {
> > + ret_freq = policy->min;
> > + cpufreq_cpu_put(policy);
> > + }
> > +
> > + return ret_freq;
> > +}
> > +EXPORT_SYMBOL(cpufreq_quick_get_min);
> > +
> > /**
> > * cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU
> > * @cpu: CPU number
> > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> > index 172ff51c1b2a..c74dcb5f9263 100644
> > --- a/include/linux/cpufreq.h
> > +++ b/include/linux/cpufreq.h
> > @@ -220,6 +220,7 @@ static inline bool policy_is_shared(struct cpufreq_policy *policy)
> > unsigned int cpufreq_get(unsigned int cpu);
> > unsigned int cpufreq_quick_get(unsigned int cpu);
> > unsigned int cpufreq_quick_get_max(unsigned int cpu);
> > +unsigned int cpufreq_quick_get_min(unsigned int cpu);
> > unsigned int cpufreq_get_hw_max_freq(unsigned int cpu);
> > void disable_cpufreq(void);
> >
> > @@ -250,6 +251,10 @@ static inline unsigned int cpufreq_quick_get_max(unsigned int cpu)
> > {
> > return 0;
> > }
> > +static inline unsigned int cpufreq_quick_get_min(unsigned int cpu)
> > +{
> > + return 0;
> > +}
> > static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
> > {
> > return 0;
> > --
> > 2.25.1
> >
> >
Hi Doug,
On Tue, Jul 25, 2023 at 9:12 PM Doug Smythies <[email protected]> wrote:
>
> Hi Rafael,
>
> On Tue, Jul 25, 2023 at 11:31 AM Rafael J. Wysocki <[email protected]> wrote:
> > On Tue, Jul 25, 2023 at 2:14 AM Doug Smythies <[email protected]> wrote:
> > >
> > > Currently, when the CPU frequency is stale the nominal clock frequency
> > > is returned by calls to arch_freq_get_on_cpu(). Some users are
> > > confused by the high reported frequency when their system is idle
> > > and/or it is above a reduced maximum they set.
> > >
> > > This patch will return the policy minimum as the stale frequency reply
> > > from arch_freq_get_on_cpu().
> > >
> > > Reported-by: Yang Jie <[email protected]>
> > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217597
> > > Signed-off-by: Doug Smythies <[email protected]>
> > > ---
> > > arch/x86/kernel/cpu/aperfmperf.c | 13 +++++--------
> > > drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++
> > > include/linux/cpufreq.h | 5 +++++
> > > 3 files changed, 28 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
> > > index fdbb5f07448f..44cc96864d94 100644
> > > --- a/arch/x86/kernel/cpu/aperfmperf.c
> > > +++ b/arch/x86/kernel/cpu/aperfmperf.c
> > > @@ -418,9 +418,10 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > > unsigned long last;
> > > u64 acnt, mcnt;
> > >
> > > - if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> > > - goto fallback;
> > > -
> > > + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)){
> > > + freq = cpufreq_quick_get(cpu);
> > > + return freq ? freq : cpufreq_quick_get_min(cpu);
> > > + }
> > > do {
> > > seq = raw_read_seqcount_begin(&s->seq);
> > > last = s->last_update;
> > > @@ -433,13 +434,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > > * which covers idle and NOHZ full CPUs.
> > > */
> > > if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
> > > - goto fallback;
> > > + return cpufreq_quick_get_min(cpu);
> > >
> > > return div64_u64((cpu_khz * acnt), mcnt);
> > > -
> > > -fallback:
> > > - freq = cpufreq_quick_get(cpu);
> > > - return freq ? freq : cpu_khz;
> >
> > It looks to me like modifying cpufreq_quick_get) to return policy->min
> > if policy->cur is 0 would work in a similar way, wouldn't it?
>
> For the configuration of intel_cpufreq driver (intel_pstate in
> passive mode), schedutil governor, HWP enabled, for
> a stale frequency policy->cur is not 0 and will always
> be whatever the min value was when the driver was initialized,
> regardless of what has been set since.
So I would prefer to address this in the intel_pstate driver than to
work around it in the core.
> The patch I submitted deals with that situation also.
>
> A complete list of driver/governor/HWP stale frequency
> replies can be found on the bugzilla report at:
>
> https://bugzilla.kernel.org/attachment.cgi?id=304694
>
> There might be push back on some of the performance
> governor stale frequency replies. I could not figure out
> a performance governor dependant reply.
>
> Also there are other callers to cpufreq_quick_get
> and I was not sure I could mess with the function
> response for them. For example
> drivers/devfreq/tegra30-devfreq.c
> and drivers/thermal/cpufreq_cooling.c
> and drivers/powercap/dtpm_cpu.c
IIUC, all of the above rely on policy->cur being nonzero.
There are other users doing questionable things when
cpufreq_quick_get() returns 0 that I think would be better off if the
min is returned instead.
Hi Rafael,
On Wed, Jul 26, 2023 at 7:43 AM Rafael J. Wysocki <[email protected]> wrote:
> On Tue, Jul 25, 2023 at 9:12 PM Doug Smythies <[email protected]> wrote:
> > On Tue, Jul 25, 2023 at 11:31 AM Rafael J. Wysocki <[email protected]> wrote:
> > > On Tue, Jul 25, 2023 at 2:14 AM Doug Smythies <[email protected]> wrote:
> > > >
> > > > Currently, when the CPU frequency is stale the nominal clock frequency
> > > > is returned by calls to arch_freq_get_on_cpu(). Some users are
> > > > confused by the high reported frequency when their system is idle
> > > > and/or it is above a reduced maximum they set.
> > > >
> > > > This patch will return the policy minimum as the stale frequency reply
> > > > from arch_freq_get_on_cpu().
> > > >
> > > > Reported-by: Yang Jie <[email protected]>
> > > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217597
> > > > Signed-off-by: Doug Smythies <[email protected]>
> > > > ---
> > > > arch/x86/kernel/cpu/aperfmperf.c | 13 +++++--------
> > > > drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++
> > > > include/linux/cpufreq.h | 5 +++++
> > > > 3 files changed, 28 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
> > > > index fdbb5f07448f..44cc96864d94 100644
> > > > --- a/arch/x86/kernel/cpu/aperfmperf.c
> > > > +++ b/arch/x86/kernel/cpu/aperfmperf.c
> > > > @@ -418,9 +418,10 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > > > unsigned long last;
> > > > u64 acnt, mcnt;
> > > >
> > > > - if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
> > > > - goto fallback;
> > > > -
> > > > + if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF)){
> > > > + freq = cpufreq_quick_get(cpu);
> > > > + return freq ? freq : cpufreq_quick_get_min(cpu);
> > > > + }
> > > > do {
> > > > seq = raw_read_seqcount_begin(&s->seq);
> > > > last = s->last_update;
> > > > @@ -433,13 +434,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> > > > * which covers idle and NOHZ full CPUs.
> > > > */
> > > > if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
> > > > - goto fallback;
> > > > + return cpufreq_quick_get_min(cpu);
> > > >
> > > > return div64_u64((cpu_khz * acnt), mcnt);
> > > > -
> > > > -fallback:
> > > > - freq = cpufreq_quick_get(cpu);
> > > > - return freq ? freq : cpu_khz;
> > >
> > > It looks to me like modifying cpufreq_quick_get) to return policy->min
> > > if policy->cur is 0 would work in a similar way, wouldn't it?
> >
> > For the configuration of intel_cpufreq driver (intel_pstate in
> > passive mode), schedutil governor, HWP enabled, for
> > a stale frequency policy->cur is not 0 and will always
> > be whatever the min value was when the driver was initialized,
> > regardless of what has been set since.
>
> So I would prefer to address this in the intel_pstate driver than to
> work around it in the core.
Okay, but I would need some help with it. I already tried to
figure out a fix before starting this thread, and have tried
again since your comment. I haven't been able to figure
it out.
An example of the issue:
Use the ondemand governor and set some
minimum and also put a load on CPU 5 such that the
governor asks for a non-min and non-max pstate.
Then switch to the schedutil governor, and terminate
the load on CPU 5, and look at CPU frequencies:
$ grep . /sys/devices/system/cpu/cpufreq/policy*/scaling_cur_freq
/sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy10/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy11/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy1/scaling_cur_freq:4799871
/sys/devices/system/cpu/cpufreq/policy2/scaling_cur_freq:4800027
/sys/devices/system/cpu/cpufreq/policy3/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy4/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy5/scaling_cur_freq:1300000
/sys/devices/system/cpu/cpufreq/policy6/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy7/scaling_cur_freq:4800736
/sys/devices/system/cpu/cpufreq/policy8/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy9/scaling_cur_freq:1000000
non stale frequencies are identified by non round numbers.
observe that CPU 5 still indicates pstate 13.
observe the other stale frequencies are the pstate 10 min
that I set when the governor was ondemand.
Now change the minimum to 1.1 GHz and check it:
$ grep . /sys/devices/system/cpu/cpufreq/policy*/scaling_min_freq
/sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy10/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy11/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy1/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy2/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy3/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy4/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy5/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy6/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy7/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy8/scaling_min_freq:1100000
/sys/devices/system/cpu/cpufreq/policy9/scaling_min_freq:1100000
and look at current again:
$ grep . /sys/devices/system/cpu/cpufreq/policy*/scaling_cur_freq
/sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy10/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy11/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy1/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy2/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy3/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy4/scaling_cur_freq:1000000
/sys/devices/system/cpu/cpufreq/policy5/scaling_cur_freq:1300000
/sys/devices/system/cpu/cpufreq/policy6/scaling_cur_freq:4800585
/sys/devices/system/cpu/cpufreq/policy7/scaling_cur_freq:4800177
/sys/devices/system/cpu/cpufreq/policy8/scaling_cur_freq:4799992
/sys/devices/system/cpu/cpufreq/policy9/scaling_cur_freq:4800015
Observe the stale frequencies are unchanged and outside of the
range limits.
> > The patch I submitted deals with that situation also.
> >
> > A complete list of driver/governor/HWP stale frequency
> > replies can be found on the bugzilla report at:
> >
> > https://bugzilla.kernel.org/attachment.cgi?id=304694
> >
> > There might be push back on some of the performance
> > governor stale frequency replies. I could not figure out
> > a performance governor dependant reply.
> >
> > Also there are other callers to cpufreq_quick_get
> > and I was not sure I could mess with the function
> > response for them. For example
> > drivers/devfreq/tegra30-devfreq.c
> > and drivers/thermal/cpufreq_cooling.c
> > and drivers/powercap/dtpm_cpu.c
>
> IIUC, all of the above rely on policy->cur being nonzero.
>
> There are other users doing questionable things when
> cpufreq_quick_get() returns 0 that I think would be better off if the
> min is returned instead.
Okay, I'll submit a new patch shortly, with this:
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 50bbc969ffe5..4e91169a83f5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1768,7 +1768,7 @@ unsigned int cpufreq_quick_get(unsigned int cpu)
policy = cpufreq_cpu_get(cpu);
if (policy) {
- ret_freq = policy->cur;
+ ret_freq = policy->cur ? policy->cur : policy->min;
cpufreq_cpu_put(policy);
}
The testing results are in the bugzilla report here:
https://bugzilla.kernel.org/attachment.cgi?id=304734
... Doug