The policy->cpuinfo.max_freq and policy->max updates in
intel_cpufreq_turbo_update() are excessive as they are done for no
good reason and may lead to problems in principle, so they should be
dropped. However, after dropping them intel_cpufreq_turbo_update()
becomes almost entirely pointless, because the check made by it is
made again down the road in intel_pstate_prepare_request(). The
only thing in it that still needs to be done is the call to
update_turbo_state(), so drop intel_cpufreq_turbo_update() altogether
and make its callers invoke update_turbo_state() directly instead of
it.
In addition to that, fix intel_cpufreq_verify_policy() so that it
checks global.no_turbo in addition to global.turbo_disabled when
updating policy->cpuinfo.max_freq to make it consistent with
intel_pstate_verify_policy().
Fixes: 001c76f05b (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In the active mode intel_pstate currently uses two sets of global
limits, each associated with one of the possible scaling_governor
settings in that mode: "powersave" or "performance".
The driver switches over from one of those sets to the other
depending on the scaling_governor setting for the last CPU whose
per-policy cpufreq interface in sysfs was last used to change
parameters exposed in there. That obviously leads to no end of
issues when the scaling_governor settings differ between CPUs.
The most recent issue was introduced by commit a240c4aa5d (cpufreq:
intel_pstate: Do not reinit performance limits in ->setpolicy)
that eliminated the reinitialization of "performance" limits in
intel_pstate_set_policy() preventing the max limit from being set
to anything below 100, among other things.
Namely, an undesirable side effect of commit a240c4aa5d is that
now, after setting scaling_governor to "performance" in the active
mode, the per-policy limits for the CPU in question go to the highest
level and stay there even when it is switched back to "powersave"
later.
As it turns out, some distributions set scaling_governor to
"performance" temporarily for all CPUs to speed-up system
initialization, so that change causes them to misbehave later.
To fix that, get rid of the performance/powersave global limits
split and use just one set of global limits for everything.
From the user's persepctive, after this modification, when
scaling_governor is switched from "performance" to "powersave"
or the other way around on one CPU, the limits settings (ie. the
global max/min_perf_pct and per-policy scaling_max/min_freq for
any CPUs) will not change. Still, switching from "performance"
to "powersave" or the other way around changes the way in which
P-states are selected and in particular "performance" causes the
driver to always request the highest P-state it is allowed to ask
for for the given CPU.
Fixes: a240c4aa5d (cpufreq: intel_pstate: Do not reinit performance limits in ->setpolicy)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently, intel_pstate_update_perf_limits() first converts the
policy minimum and maximum limits into percentages of the maximum
turbo frequency (rounding up to an integer) and then converts these
percentages to fractions (by using fixed-point arithmetic to divide
them by 100).
That introduces a rounding error unnecessarily, because the fractions
can be obtained by carrying out fixed-point divisions directly on the
input numbers.
Rework the computations in intel_pstate_hwp_set() to use fractions
instead of percentages (and drop redundant local variables from
there) and modify intel_pstate_update_perf_limits() to compute the
fractions directly and percentages out of them.
While at it, introduce percent_ext_fp() for converting percentages
to fractions (with extended number of fraction bits) and use it in
the computations.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In the functions intel_pstate_hwp_set(), min/max range from HWP capability
MSR along with max_perf_pct and min_perf_pct, is used to set the HWP
request MSR. In some cases this doesn't result in the correct HWP max/min
in HWP request.
For example: In the following case:
HWP capabilities from MSR 0x771
0x70a1220
Here cpufreq min/max frequencies from above MSR dump are 700MHz and 3.2GHz
respectively.
This will result in
hwp_min = 0x07
hwp_max = 0x20
To limit max frequency to 2GHz:
perf_limits->max_perf_pct = 63 (2GHz as a percent of 3.2GHz rounded up)
With the current calculation:
adj_range = max_perf_pct * range / 100;
adj_range = 63 * (32 - 7) / 100
adj_range = 15
max = hw_min + adj_range;
max = 7 + 15 = 22
This will result in HWP request of 0x160f, which will result in a
frequency cap of 2.2GHz not 2GHz.
The problem with the above calculation is that hwp_min of 7 is treated
as 0% in the range. But max_perf_pct is calculated with respect to minimum
as 0 and max as 3.2GHz or hwp_max, so adding hwp_min to it will result in
more than the desired.
Since the min_perf_pct and max_perf_pct is already a percent of max
frequency or hwp_max, this min/max HWP request value can be calculated
directly applying these percentage to hwp_max.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Fix the debugfs interface for PID tuning to actually update
pid_params.sample_rate_ns on PID parameters updates, as changing
pid_params.sample_rate_ms via debugfs has no effect now.
Fixes: a4675fbc4a (cpufreq: intel_pstate: Replace timers with utilization update callbacks)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
intel_pstate_hwp_set_policy() is a wrapper around
intel_pstate_hwp_set(), but the only value it adds is to check
hwp_active before calling the latter and one of its two callers
has already checked hwp_active before that happens, so in that
code path the additional check is redundant and using the wrapper
is rather pointless.
For this reason, drop intel_pstate_hwp_set_policy() and make its
callers invoke intel_pstate_hwp_set() directly (after checking
hwp_active).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
* pm-cpufreq:
cpufreq: intel_pstate: Do not reinit performance limits in ->setpolicy
cpufreq: intel_pstate: Fix intel_pstate_verify_policy()
cpufreq: intel_pstate: Fix global settings in active mode
cpufreq: Add the "cpufreq.off=1" cmdline option
cpufreq: intel_pstate: Avoid triggering cpu_frequency tracepoint unnecessarily
cpufreq: intel_pstate: Fix intel_cpufreq_verify_policy()
cpufreq: intel_pstate: Do not use performance_limits in passive mode
If the current P-state selection algorithm is set to "performance"
in intel_pstate_set_policy(), the limits may be initialized from
scratch, but only if no_turbo is not set and the maximum frequency
allowed for the given CPU (i.e. the policy object representing it)
is at least equal to the max frequency supported by the CPU. In all
of the other cases, the limits will not be updated.
For example, the following can happen:
# cat intel_pstate/status
active
# echo performance > cpufreq/policy0/scaling_governor
# cat intel_pstate/min_perf_pct
100
# echo 94 > intel_pstate/min_perf_pct
# cat intel_pstate/min_perf_pct
100
# cat cpufreq/policy0/scaling_max_freq
3100000
echo 3000000 > cpufreq/policy0/scaling_max_freq
# cat intel_pstate/min_perf_pct
94
# echo 95 > intel_pstate/min_perf_pct
# cat intel_pstate/min_perf_pct
95
That is confusing for two reasons. First, the initial attempt to
change min_perf_pct to 94 seems to have no effect, even though
setting the global limits should always work. Second, after
changing scaling_max_freq for policy0 the global min_perf_pct
attribute shows 94, even though it should have not been affected
by that operation in principle.
Moreover, the final attempt to change min_perf_pct to 95 worked
as expected, because scaling_max_freq for the only policy with
scaling_governor equal to "performance" was different from the
maximum at that time.
To make all that confusion go away, modify intel_pstate_set_policy()
so that it doesn't reinitialize the limits at all.
At the same time, change intel_pstate_set_performance_limits() to
set min_sysfs_pct to 100 in the "performance" limits set so that
switching the P-state selection algorithm to "performance" causes
intel_pstate/min_perf_pct in sysfs to go to 100 (or whatever value
min_sysfs_pct in the "performance" limits is set to later).
That requires per-CPU limits to be initialized explicitly rather
than by copying the global limits to avoid setting min_sysfs_pct
in the per-CPU limits to 100.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The code added to intel_pstate_verify_policy() by commit 1443ebbacf
(cpufreq: intel_pstate: Fix sysfs limits enforcement for performance
policy) should use perf_limits instead of limits, because otherwise
setting global limits via sysfs may affect policies inconsistently.
For example, in the sequence of shell commands below, the
scaling_min_freq attribute for policy1 and policy2 should be
affected in the same way, because scaling_governor is set in
the same way for both of them:
# cat cpufreq/policy1/scaling_governor
powersave
# cat cpufreq/policy2/scaling_governor
powersave
# echo performance > cpufreq/policy0/scaling_governor
# echo 94 > intel_pstate/min_perf_pct
# cat cpufreq/policy0/scaling_min_freq
2914000
# cat cpufreq/policy1/scaling_min_freq
2914000
# cat cpufreq/policy2/scaling_min_freq
800000
The are affected differently, because intel_pstate_verify_policy()
is invoked with limits set to &performance_limits (left behind by
policy0) for policy1 and with limits set to &powersave_limits (left
behind by policy1) for policy2. Since perf_limits is set to the
set of limits matching the policy being updated, using it instead
of limits fixes the inconsistency.
Fixes: 1443ebbacf (cpufreq: intel_pstate: Fix sysfs limits enforcement for performance policy)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Commit 111b8b3fe4 (cpufreq: intel_pstate: Always keep all
limits settings in sync) changed intel_pstate to invoke
cpufreq_update_policy() for every registered CPU on global sysfs
attributes updates, but that led to undesirable effects in the
active mode if the "performance" P-state selection algorithm is
configufred for one CPU and the "powersave" one is chosen for
all of the other CPUs.
Namely, in that case, the following is possible:
# cd /sys/devices/system/cpu/
# cat intel_pstate/max_perf_pct
100
# cat intel_pstate/min_perf_pct
26
# echo performance > cpufreq/policy0/scaling_governor
# cat intel_pstate/max_perf_pct
100
# cat intel_pstate/min_perf_pct
100
# echo 94 > intel_pstate/min_perf_pct
# cat intel_pstate/min_perf_pct
26
The reason why this happens is because intel_pstate attempts to
maintain two sets of global limits in the active mode, one for
the "performance" P-state selection algorithm and one for the
"powersave" P-state selection algorithm, but the P-state selection
algorithms are set per policy, so the global limits cannot reflect
all of them at the same time if they are different for different
policies.
In the particular situation above, the attempt to change
min_perf_pct to 94 caused cpufreq_update_policy() to be run
for a CPU with the "powersave" P-state selection algorithm
and intel_pstate_set_policy() called by it silently switched the
global limits to the "powersave" set which finally was reflected
by the sysfs interface.
To prevent that from happening, modify intel_pstate_update_policies()
to always switch back to the set of limits that was used right before
it has been invoked.
Fixes: 111b8b3fe4 (cpufreq: intel_pstate: Always keep all limits settings in sync)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In the passive mode the cpu_frequency trace event is already
triggered by the cpufreq core or by scaling governors, so
intel_pstate should not trigger it once again for the same
P-state updates.
In addition to that, the frequency returned by
intel_cpufreq_fast_switch() and passed via freqs.new from
intel_cpufreq_target() to cpufreq_freq_transition_end() should
reflect the P-state actually set, so make that happen.
Fixes: 001c76f05b (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The intel_pstate_update_perf_limits() called from
intel_cpufreq_verify_policy() may cause global P-state limits
to change which is generally confusing and unnecessary.
In the passive mode the global limits are only applied to the
frequency selected by the scaling governor (they are not taken
into account by governors when making decisions anyway), so making
them follow the per-policy limits serves no purpose and may go
against user expectations (as it generally causes the global
attributes in sysfs to change even though they have not been
written to in some cases).
Fix that by dropping the intel_pstate_update_perf_limits()
invocation from intel_cpufreq_verify_policy() (which also
reduces the code size by a few lines).
This change does not affect the per-CPU limits case, because those
limits allow any P-state to be set by default in the passive mode
and it removes the only piece of code updating them in that mode,
so the per-policy settings will be the only ones taken into account
in that case as expected.
Fixes: 001c76f05b (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Using performance_limits in the passive mode doesn't make
sense, because in that mode the global limits are applied to the
frequency selected by the scaling governor.
The maximum and minimum P-state limits in performance_limits are both
set to 100 percent which will put all CPUs into the turbo range
regardless of what governor is used and what frequencies are
selected by it (that is particularly undesirable on CPUs with the
generic powersave governor attached).
For this reason, make intel_pstate_register_driver() always point
limits to powersave_limits in the passive mode.
Fixes: 001c76f05b (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull sched.h split-up from Ingo Molnar:
"The point of these changes is to significantly reduce the
<linux/sched.h> header footprint, to speed up the kernel build and to
have a cleaner header structure.
After these changes the new <linux/sched.h>'s typical preprocessed
size goes down from a previous ~0.68 MB (~22K lines) to ~0.45 MB (~15K
lines), which is around 40% faster to build on typical configs.
Not much changed from the last version (-v2) posted three weeks ago: I
eliminated quirks, backmerged fixes plus I rebased it to an upstream
SHA1 from yesterday that includes most changes queued up in -next plus
all sched.h changes that were pending from Andrew.
I've re-tested the series both on x86 and on cross-arch defconfigs,
and did a bisectability test at a number of random points.
I tried to test as many build configurations as possible, but some
build breakage is probably still left - but it should be mostly
limited to architectures that have no cross-compiler binaries
available on kernel.org, and non-default configurations"
* 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (146 commits)
sched/headers: Clean up <linux/sched.h>
sched/headers: Remove #ifdefs from <linux/sched.h>
sched/headers: Remove the <linux/topology.h> include from <linux/sched.h>
sched/headers, hrtimer: Remove the <linux/wait.h> include from <linux/hrtimer.h>
sched/headers, x86/apic: Remove the <linux/pm.h> header inclusion from <asm/apic.h>
sched/headers, timers: Remove the <linux/sysctl.h> include from <linux/timer.h>
sched/headers: Remove <linux/magic.h> from <linux/sched/task_stack.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/init.h>
sched/core: Remove unused prefetch_stack()
sched/headers: Remove <linux/rculist.h> from <linux/sched.h>
sched/headers: Remove the 'init_pid_ns' prototype from <linux/sched.h>
sched/headers: Remove <linux/signal.h> from <linux/sched.h>
sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>
sched/headers: Remove the runqueue_is_locked() prototype
sched/headers: Remove <linux/sched.h> from <linux/sched/hotplug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/debug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/nohz.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/stat.h>
sched/headers: Remove the <linux/gfp.h> include from <linux/sched.h>
sched/headers: Remove <linux/rtmutex.h> from <linux/sched.h>
...
These update turbostat significantly and in particular:
- Default output is now verbose, --debug is no longer required to
get all counters. As a result, some options have been added to
specify exactly what output is wanted.
- Added --quiet to skip system configuration output
- Added --list, --show and --hide parameters
- Added --cpu parameter
- Enhanced Baytrail SoC support
- Added Gemini Lake SoC support
- Added sysfs C-state columns
Also the symbol definitions in arch/x86/include/asm/intel-family.h
and arch/x86/include/asm/msr-index.h are updated and the intel_idle
and intel_pstate drivers are modified to use the updated symbols.
Credits to Len Brown for all of these changes.
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Merge tag 'pm-turbostat-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull turbostat utility updates from Rafael Wysocki:
"Power management turbostat utility updates.
These update turbostat significantly and in particular:
- default output is now verbose, --debug is no longer required to get
all counters. As a result, some options have been added to specify
exactly what output is wanted.
- added --quiet to skip system configuration output
- added --list, --show and --hide parameters
- added --cpu parameter
- enhanced Baytrail SoC support
- added Gemini Lake SoC support
- added sysfs C-state columns
Also the symbol definitions in arch/x86/include/asm/intel-family.h and
arch/x86/include/asm/msr-index.h are updated and the intel_idle and
intel_pstate drivers are modified to use the updated symbols.
Credits to Len Brown for all of these changes"
* tag 'pm-turbostat-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (44 commits)
tools/power turbostat: version 17.02.24
tools/power turbostat: bugfix: --add u32 was printed as u64
tools/power turbostat: show error on exec
tools/power turbostat: dump p-state software config
tools/power turbostat: show package number, even without --debug
tools/power turbostat: support "--hide C1" etc.
tools/power turbostat: move --Package and --processor into the --cpu option
tools/power turbostat: turbostat.8 update
tools/power turbostat: update --list feature
tools/power turbostat: use wide columns to display large numbers
tools/power turbostat: Add --list option to show available header names
tools/power turbostat: fix zero IRQ count shown in one-shot command mode
tools/power turbostat: add --cpu parameter
tools/power turbostat: print sysfs C-state stats
tools/power turbostat: extend --add option to accept /sys path
tools/power turbostat: skip unused counters on BDX
tools/power turbostat: fix decoding for GLM, DNV, SKX turbo-ratio limits
tools/power turbostat: skip unused counters on SKX
tools/power turbostat: Denverton: use HW CC1 counter, skip C3, C7
tools/power turbostat: initial Gemini Lake SOC support
...
We are going to split <linux/sched/cpufreq.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/cpufreq.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull changes related to turbostat for v4.11 from Len Brown.
* 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux: (44 commits)
tools/power turbostat: version 17.02.24
tools/power turbostat: bugfix: --add u32 was printed as u64
tools/power turbostat: show error on exec
tools/power turbostat: dump p-state software config
tools/power turbostat: show package number, even without --debug
tools/power turbostat: support "--hide C1" etc.
tools/power turbostat: move --Package and --processor into the --cpu option
tools/power turbostat: turbostat.8 update
tools/power turbostat: update --list feature
tools/power turbostat: use wide columns to display large numbers
tools/power turbostat: Add --list option to show available header names
tools/power turbostat: fix zero IRQ count shown in one-shot command mode
tools/power turbostat: add --cpu parameter
tools/power turbostat: print sysfs C-state stats
tools/power turbostat: extend --add option to accept /sys path
tools/power turbostat: skip unused counters on BDX
tools/power turbostat: fix decoding for GLM, DNV, SKX turbo-ratio limits
tools/power turbostat: skip unused counters on SKX
tools/power turbostat: Denverton: use HW CC1 counter, skip C3, C7
tools/power turbostat: initial Gemini Lake SOC support
...
Originally, these MSRs were locally defined in this driver.
Now the definitions are in msr-index.h -- use them.
Signed-off-by: Len Brown <len.brown@intel.com>
There is a problem with intel_pstate operation mode switching
introduced by commit fb1fe1041c (cpufreq: intel_pstate: Operation
mode control from sysfs), because the global sysfs limits are
preserved across operation modes while per-policy limits are
reinitialized from scratch on a mode switch and both sets of limits
may get out of sync this way.
Fix that by always reinitializing the global limits upon the
registration of the driver.
Fixes: fb1fe1041c (cpufreq: intel_pstate: Operation mode control from sysfs)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Some Kabylake desktop processors may not reach max turbo when running in
HWP mode, even if running under sustained 100% utilization.
This occurs when the HWP.EPP (Energy Performance Preference) is set to
"balance_power" (0x80) -- the default on most systems.
It occurs because the platform BIOS may erroneously enable an
energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not
recommended to be enabled on this SKU.
On the failing systems, this BIOS issue was not discovered when the
desktop motherboard was tested with Windows, because the BIOS also
neglects to provide the ACPI/CPPC table, that Windows requires to enable
HWP, and so Windows runs in legacy P-state mode, where this setting has
no effect.
Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and
so it runs in HWP mode, exposing this incorrect BIOS configuration.
There are several ways to address this problem.
First, Linux can also run in legacy P-state mode on this system.
As intel_pstate is how Linux enables HWP, booting with
"intel_pstate=disable"
will run in acpi-cpufreq/ondemand legacy p-state mode.
Or second, the "performance" governor can be used with intel_pstate,
which will modify HWP.EPP to 0.
Or third, starting in 4.10, the
/sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference
attribute in can be updated from "balance_power" to "performance".
Or fourth, apply this patch, which fixes the erroneous setting of
MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default
configuration to function as designed.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: 4.6+ <stable@vger.kernel.org> # 4.6+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When HWP is active, turbo activation ratio is not used to calculate max
non turbo ratio. But on these systems the max non turbo ratio is decided
by config TDP settings.
This change removes usage of MSR_TURBO_ACTIVATION_RATIO for HWP systems,
instead directly use TDP ratios, when more than one TDPs are available.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Under HWP the performance limits are calculated using max_perf_pct
and min_perf_pct using possible performance, not available performance.
The available performance can be reduced by no_turbo setting. To make
compatible with legacy mode, use max/min performance percentage with
respect to available performance.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When turbo is not disabled by BIOS, but user disabled from intel P-State
sysfs and changes max/min using cpufreq sysfs, the resultant frequency
is lower than what user requested.
The reason for this, when the perf limits are calculated in set_policy()
callback, they are with reference to max cpu frequency (turbo frequency
), but when enforced in the intel_pstate_get_min_max() they are with
reference to max available performance as documented in the intel_pstate
documentation (in this case max non turbo P-State).
This needs similar change as done in intel_cpufreq_verify_policy() for
passive mode. Set policy->cpuinfo.max_freq based on the turbo status.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Make it possible to change the operation mode of intel_pstate with
the help of a new sysfs attribute called "status".
There are three possible configurations that can be selected using
this attribute:
"off" - The driver is not in use at this time.
"active" - The driver works as a P-state governor (default).
"passive" - The driver works as a regular cpufreq one and collaborates
with the generic cpufreq governors (it sets P-states as
requested by those governors). [This is the same mode
the driver can be started in by passing intel_pstate=passive
in the kernel command line.]
The current setting is returned by reads from this attribute. Writing
one of the above strings to it changes the operation mode as indicated
by that string, if possible.
If HW-managed P-states (HWP) feature is enabled, it is not possible
to change the driver's operation mode and attempts to write to this
attribute will fail.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Expose the intel_pstate's global sysfs attributes before registering
the driver to prepare for the addition of an attribute that also will
have to work if the driver is not registered.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
A side effect of keeping intel_pstate sysfs limits in sync with cpufreq
is that the now sysfs limits can't enforced under performance policy.
For example, if the max_perf_pct is changed from 100 to 80, this will call
intel_pstate_set_policy(), which will change the max_perf to 100 again for
performance policy. Same issue happens, when no_turbo is set.
This change calculates max and min frequency using sysfs performance
limits in intel_pstate_verify_policy() and adjusts policy limits by
calling cpufreq_verify_within_limits().
Also, it causes the setting of performance limits to be skipped if
no_turbo is set.
Fixes: 111b8b3fe4 (cpufreq: intel_pstate: Always keep all limits settings in sync)
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* pm-cpufreq:
cpufreq: dt: Add support for APM X-Gene 2
cpufreq: intel_pstate: Always keep all limits settings in sync
cpufreq: intel_pstate: Use locking in intel_cpufreq_verify_policy()
cpufreq: intel_pstate: Use locking in intel_pstate_resume()
cpufreq: intel_pstate: Do not expose PID parameters in passive mode
Make intel_pstate update per-logical-CPU limits when the global
settings are changed to ensure that they are always in sync and
users will not see confusing values in per-logical-CPU sysfs
attributes.
This also fixes the problem that setting the "no_turbo" global
attribute to 1 in the "passive" mode (ie. when intel_pstate acts
as a regular cpufreq driver) when scaling_governor is set to
"performance" has no effect.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Race conditions are possible if intel_cpufreq_verify_policy()
is executed in parallel with global limits updates from sysfs,
so the invocation of intel_pstate_update_perf_limits() in it
should be carried out under intel_pstate_limits_lock.
Make that happen.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Theoretically, intel_pstate_resume() may be executed in parallel
with intel_pstate_set_policy(), if the latter is invoked via
cpufreq_update_policy() as a result of a notification, so use
intel_pstate_limits_lock in there too to avoid race conditions.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
If intel_pstate works in the passive mode in which it acts as
a regular cpufreq driver and collaborates with generic cpufreq
governors, the PID parameters are not used, so do not expose
them via debugfs in that case.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
- New cpufreq driver for Broadcom STB SoCs and a Device Tree binding
for it (Markus Mayer).
- Support for ARM Integrator/AP and Integrator/CP in the generic
DT cpufreq driver and elimination of the old Integrator cpufreq
driver (Linus Walleij).
- Support for the zx296718, r8a7743 and r8a7745, Socionext UniPhier,
and PXA SoCs in the the generic DT cpufreq driver (Baoyou Xie,
Geert Uytterhoeven, Masahiro Yamada, Robert Jarzmik).
- cpufreq core fix to eliminate races that may lead to using
inactive policy objects and related cleanups (Rafael Wysocki).
- cpufreq schedutil governor update to make it use SCHED_FIFO
kernel threads (instead of regular workqueues) for doing delayed
work (to reduce the response latency in some cases) and related
cleanups (Viresh Kumar).
- New cpufreq sysfs attribute for resetting statistics (Markus
Mayer).
- cpufreq governors fixes and cleanups (Chen Yu, Stratos Karafotis,
Viresh Kumar).
- Support for using generic cpufreq governors in the intel_pstate
driver (Rafael Wysocki).
- Support for per-logical-CPU P-state limits and the EPP/EPB
(Energy Performance Preference/Energy Performance Bias) knobs
in the intel_pstate driver (Srinivas Pandruvada).
- New CPU ID for Knights Mill in intel_pstate (Piotr Luc).
- intel_pstate driver modification to use the P-state selection
algorithm based on CPU load on platforms with the system profile
in the ACPI tables set to "mobile" (Srinivas Pandruvada).
- intel_pstate driver cleanups (Arnd Bergmann, Rafael Wysocki,
Srinivas Pandruvada).
- cpufreq powernv driver updates including fast switching support
(for the schedutil governor), fixes and cleanus (Akshay Adiga,
Andrew Donnellan, Denis Kirjanov).
- acpi-cpufreq driver rework to switch it over to the new CPU
offline/online state machine (Sebastian Andrzej Siewior).
- Assorted cleanups in cpufreq drivers (Wei Yongjun, Prashanth
Prakash).
- Idle injection rework (to make it use the regular idle path
instead of a home-grown custom one) and related powerclamp
thermal driver updates (Peter Zijlstra, Jacob Pan, Petr Mladek,
Sebastian Andrzej Siewior).
- New CPU IDs for Atom Z34xx and Knights Mill in intel_idle (Andy
Shevchenko, Piotr Luc).
- intel_idle driver cleanups and switch over to using the new CPU
offline/online state machine (Anna-Maria Gleixner, Sebastian
Andrzej Siewior).
- cpuidle DT driver update to support suspend-to-idle properly
(Sudeep Holla).
- cpuidle core cleanups and misc updates (Daniel Lezcano, Pan Bian,
Rafael Wysocki).
- Preliminary support for power domains including CPUs in the
generic power domains (genpd) framework and related DT bindings
(Lina Iyer).
- Assorted fixes and cleanups in the generic power domains (genpd)
framework (Colin Ian King, Dan Carpenter, Geert Uytterhoeven).
- Preliminary support for devices with multiple voltage regulators
and related fixes and cleanups in the Operating Performance Points
(OPP) library (Viresh Kumar, Masahiro Yamada, Stephen Boyd).
- System sleep state selection interface rework to make it easier
to support suspend-to-idle as the default system suspend method
(Rafael Wysocki).
- PM core fixes and cleanups, mostly related to the interactions
between the system suspend and runtime PM frameworks (Ulf Hansson,
Sahitya Tummala, Tony Lindgren).
- Latency tolerance PM QoS framework imorovements (Andrew
Lutomirski).
- New Knights Mill CPU ID for the Intel RAPL power capping driver
(Piotr Luc).
- Intel RAPL power capping driver fixes, cleanups and switch over
to using the new CPU offline/online state machine (Jacob Pan,
Thomas Gleixner, Sebastian Andrzej Siewior).
- Fixes and cleanups in the exynos-ppmu, exynos-nocp, rk3399_dmc,
rockchip-dfi devfreq drivers and the devfreq core (Axel Lin,
Chanwoo Choi, Javier Martinez Canillas, MyungJoo Ham, Viresh
Kumar).
- Fix for false-positive KASAN warnings during resume from ACPI S3
(suspend-to-RAM) on x86 (Josh Poimboeuf).
- Memory map verification during resume from hibernation on x86 to
ensure a consistent address space layout (Chen Yu).
- Wakeup sources debugging enhancement (Xing Wei).
- rockchip-io AVS driver cleanup (Shawn Lin).
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Merge tag 'pm-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Again, cpufreq gets more changes than the other parts this time (one
new driver, one old driver less, a bunch of enhancements of the
existing code, new CPU IDs, fixes, cleanups)
There also are some changes in cpuidle (idle injection rework, a
couple of new CPU IDs, online/offline rework in intel_idle, fixes and
cleanups), in the generic power domains framework (mostly related to
supporting power domains containing CPUs), and in the Operating
Performance Points (OPP) library (mostly related to supporting devices
with multiple voltage regulators)
In addition to that, the system sleep state selection interface is
modified to make it easier for distributions with unchanged user space
to support suspend-to-idle as the default system suspend method, some
issues are fixed in the PM core, the latency tolerance PM QoS
framework is improved a bit, the Intel RAPL power capping driver is
cleaned up and there are some fixes and cleanups in the devfreq
subsystem
Specifics:
- New cpufreq driver for Broadcom STB SoCs and a Device Tree binding
for it (Markus Mayer)
- Support for ARM Integrator/AP and Integrator/CP in the generic DT
cpufreq driver and elimination of the old Integrator cpufreq driver
(Linus Walleij)
- Support for the zx296718, r8a7743 and r8a7745, Socionext UniPhier,
and PXA SoCs in the the generic DT cpufreq driver (Baoyou Xie,
Geert Uytterhoeven, Masahiro Yamada, Robert Jarzmik)
- cpufreq core fix to eliminate races that may lead to using inactive
policy objects and related cleanups (Rafael Wysocki)
- cpufreq schedutil governor update to make it use SCHED_FIFO kernel
threads (instead of regular workqueues) for doing delayed work (to
reduce the response latency in some cases) and related cleanups
(Viresh Kumar)
- New cpufreq sysfs attribute for resetting statistics (Markus Mayer)
- cpufreq governors fixes and cleanups (Chen Yu, Stratos Karafotis,
Viresh Kumar)
- Support for using generic cpufreq governors in the intel_pstate
driver (Rafael Wysocki)
- Support for per-logical-CPU P-state limits and the EPP/EPB (Energy
Performance Preference/Energy Performance Bias) knobs in the
intel_pstate driver (Srinivas Pandruvada)
- New CPU ID for Knights Mill in intel_pstate (Piotr Luc)
- intel_pstate driver modification to use the P-state selection
algorithm based on CPU load on platforms with the system profile in
the ACPI tables set to "mobile" (Srinivas Pandruvada)
- intel_pstate driver cleanups (Arnd Bergmann, Rafael Wysocki,
Srinivas Pandruvada)
- cpufreq powernv driver updates including fast switching support
(for the schedutil governor), fixes and cleanus (Akshay Adiga,
Andrew Donnellan, Denis Kirjanov)
- acpi-cpufreq driver rework to switch it over to the new CPU
offline/online state machine (Sebastian Andrzej Siewior)
- Assorted cleanups in cpufreq drivers (Wei Yongjun, Prashanth
Prakash)
- Idle injection rework (to make it use the regular idle path instead
of a home-grown custom one) and related powerclamp thermal driver
updates (Peter Zijlstra, Jacob Pan, Petr Mladek, Sebastian Andrzej
Siewior)
- New CPU IDs for Atom Z34xx and Knights Mill in intel_idle (Andy
Shevchenko, Piotr Luc)
- intel_idle driver cleanups and switch over to using the new CPU
offline/online state machine (Anna-Maria Gleixner, Sebastian
Andrzej Siewior)
- cpuidle DT driver update to support suspend-to-idle properly
(Sudeep Holla)
- cpuidle core cleanups and misc updates (Daniel Lezcano, Pan Bian,
Rafael Wysocki)
- Preliminary support for power domains including CPUs in the generic
power domains (genpd) framework and related DT bindings (Lina Iyer)
- Assorted fixes and cleanups in the generic power domains (genpd)
framework (Colin Ian King, Dan Carpenter, Geert Uytterhoeven)
- Preliminary support for devices with multiple voltage regulators
and related fixes and cleanups in the Operating Performance Points
(OPP) library (Viresh Kumar, Masahiro Yamada, Stephen Boyd)
- System sleep state selection interface rework to make it easier to
support suspend-to-idle as the default system suspend method
(Rafael Wysocki)
- PM core fixes and cleanups, mostly related to the interactions
between the system suspend and runtime PM frameworks (Ulf Hansson,
Sahitya Tummala, Tony Lindgren)
- Latency tolerance PM QoS framework imorovements (Andrew Lutomirski)
- New Knights Mill CPU ID for the Intel RAPL power capping driver
(Piotr Luc)
- Intel RAPL power capping driver fixes, cleanups and switch over to
using the new CPU offline/online state machine (Jacob Pan, Thomas
Gleixner, Sebastian Andrzej Siewior)
- Fixes and cleanups in the exynos-ppmu, exynos-nocp, rk3399_dmc,
rockchip-dfi devfreq drivers and the devfreq core (Axel Lin,
Chanwoo Choi, Javier Martinez Canillas, MyungJoo Ham, Viresh Kumar)
- Fix for false-positive KASAN warnings during resume from ACPI S3
(suspend-to-RAM) on x86 (Josh Poimboeuf)
- Memory map verification during resume from hibernation on x86 to
ensure a consistent address space layout (Chen Yu)
- Wakeup sources debugging enhancement (Xing Wei)
- rockchip-io AVS driver cleanup (Shawn Lin)"
* tag 'pm-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (127 commits)
devfreq: rk3399_dmc: Don't use OPP structures outside of RCU locks
devfreq: rk3399_dmc: Remove dangling rcu_read_unlock()
devfreq: exynos: Don't use OPP structures outside of RCU locks
Documentation: intel_pstate: Document HWP energy/performance hints
cpufreq: intel_pstate: Support for energy performance hints with HWP
cpufreq: intel_pstate: Add locking around HWP requests
PM / sleep: Print active wakeup sources when blocking on wakeup_count reads
PM / core: Fix bug in the error handling of async suspend
PM / wakeirq: Fix dedicated wakeirq for drivers not using autosuspend
PM / Domains: Fix compatible for domain idle state
PM / OPP: Don't WARN on multiple calls to dev_pm_opp_set_regulators()
PM / OPP: Allow platform specific custom set_opp() callbacks
PM / OPP: Separate out _generic_set_opp()
PM / OPP: Add infrastructure to manage multiple regulators
PM / OPP: Pass struct dev_pm_opp_supply to _set_opp_voltage()
PM / OPP: Manage supply's voltage/current in a separate structure
PM / OPP: Don't use OPP structure outside of rcu protected section
PM / OPP: Reword binding supporting multiple regulators per device
PM / OPP: Fix incorrect cpu-supply property in binding
cpuidle: Add a kerneldoc comment to cpuidle_use_deepest_state()
..
It is possible to provide hints to the HWP algorithms in the processor
to be more performance centric to more energy centric. These hints are
provided by using HWP energy performance preference (EPP) or energy
performance bias (EPB) settings.
The scope of these settings is per logical processor, which means that
each of the logical processors in the package can be programmed with a
different value.
This change provides cpufreq sysfs interface to provide hint. For each
policy, two additional attributes will be available to check and provide
hint. These attributes will only be present when the intel_pstate driver
is using HWP mode.
These attributes are:
- energy_performance_available_preferences
- energy_performance_preference
To get list of supported hints:
$ cat energy_performance_available_preferences
default performance balance_performance balance_power power
The current preference can be read or changed via cpufreq sysfs
attribute "energy_performance_preference". Reading from this attribute
will display current effective setting changed via any method. User can
write any of the valid preference string to this attribute. User can
always restore to power-on default by writing "default".
Implementation
Since these hints can be provided by direct MSR write or using some tools
like x86_energy_perf_policy, the driver internally doesn't maintain any
state. The user operation will result in direct read/write of MSR: 0x774
(HWP_REQUEST_MSR). Also driver use read modify write to update other
fields in this MSR.
Summary of changes:
- struct cpudata field epp_saved is renamed to epp_powersave, as this
stores the value to restore once policy is switched from performance
to powersave to restore original powersave EPP value.
- A new struct cpudata field epp_saved is used to store the raw MSR
EPP/EPB value when a CPU goes offline or on suspend and restore on
online/resume. This ensures that EPP value is restored to correct
value irrespective of the means used to set.
- EPP/EPB value ranges are fixed for each preference, which can be
set for the cpufreq sysfs, so user request is mapped to/from this
range.
- New attributes are only added when HWP is present.
- Since EPP value of 0 is valid the fields are initialized to
-EINVAL when not valid. The field epp_default is read only once
after powerup to avoid reading on subsequent CPU online operation
- New suspend callback to store epp on suspend operation
- Don't invalidate old epp_saved field on resume and online as now
we can restore last epp value on suspend and this field can still
have old EPP value sampled during switch to performance from
powersave.
- While here optimized setting of cpu_data->epp_powersave = epp in
intel_pstate_hwp_set() as this was done in both true and false
paths.
- epp/epb set function returns error to caller on failure to pass
on to user space for display.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To avoid race conditions from multiple threads, increase the scope
of intel_pstate_limits_lock to include HWP requests also.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add Knights Mill (KNM) to the list of CPUIDs supported by intel_pstate.
Signed-off-by: Piotr Luc <piotr.luc@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The addition of the generic governor support marked the
intel_pstate_exit_perf_limits as inline(), which fixed a warning,
but it introduced another warning:
drivers/cpufreq/intel_pstate.c: In function ‘intel_pstate_exit_perf_limits’:
drivers/cpufreq/intel_pstate.c:483:1: error: no return statement in function returning non-void [-Werror=return-type]
This changes it back to a 'void' return type, and changes the
corresponding intel_pstate_init_acpi_perf_limits() function to
be inline as well for consistency.
Fixes: 001c76f05b (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When user has selected performance policy, then set the EPP (Energy
Performance Preference) or EPB (Energy Performance Bias) to maximum
performance mode.
Also when user switch back to powersave, then restore EPP/EPB to last
EPP/EPB value before entering performance mode. If user has not changed
EPP/EPB manually then it will be power on default value.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Even with round up of limits->min_perf and limits->max_perf, in some
cases resultant performance is 100 MHz less than the desired.
For example when the maximum frequency is 3.50 GHz, setting
scaling_min_frequency to 2.3 GHz always results in 2.2 GHz minimum.
Currently the fixed floating point operation uses 8 bit precision for
calculating limits->min_perf and limits->max_perf. For some operations
in this driver the 14 bit precision is used. Using the 14 bit precision
also for calculating limits->min_perf and limits->max_perf, addresses
this issue.
Introduced fp_ext_toint() equivalent to fp_toint() and int_ext_tofp()
equivalent to int_tofp() with 14 bit precision.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In some use cases, user wants to enforce a minimum performance limit on
CPUs. But because of simple division the resultant performance is 100 MHz
less than the desired in some cases.
For example when the maximum frequency is 3.50 GHz, setting
scaling_min_frequency to 1.6 GHz always results in 1.5 GHz minimum. With
simple round up, the frequency can be set to 1.6 GHz to minimum in this
case. This round up is already done to max_policy_pct and max_perf, so do
the same for min_policy_pct and min_perf.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
There may be reasons to use generic cpufreq governors (eg. schedutil)
on Intel platforms instead of the intel_pstate driver's internal
governor. However, that currently can only be done by disabling
intel_pstate altogether and using the acpi-cpufreq driver instead
of it, which is subject to limitations.
First of all, acpi-cpufreq only works on systems where the _PSS
object is present in the ACPI tables for all logical CPUs. Second,
on those systems acpi-cpufreq will only use frequencies listed by
_PSS which may be suboptimal. In particular, by convention, the
whole turbo range is represented in _PSS as a single P-state and
the frequency assigned to it is greater by 1 MHz than the greatest
non-turbo frequency listed by _PSS. That may confuse governors to
use turbo frequencies less frequently which may lead to suboptimal
performance.
For this reason, make it possible to use the intel_pstate driver
with generic cpufreq governors as a "normal" cpufreq driver. That
mode is enforced by adding intel_pstate=passive to the kernel
command line and cannot be disabled at run time. In that mode,
intel_pstate provides a cpufreq driver interface including
the ->target() and ->fast_switch() callbacks and is listed in
scaling_driver as "intel_cpufreq".
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Doug Smythies <dsmythies@telus.net>
Currently, intel_pstate is unable to control P-states on my
IvyBridge-based Acer Aspire S5, because they are controlled by SMM
on that machine by default and it is necessary to request OS control
of P-states from it via the SMI Command register exposed in the ACPI
FADT. intel_pstate doesn't do that now, but acpi-cpufreq and other
cpufreq drivers for x86 platforms do.
Address this problem by making intel_pstate use the ACPI-defined
mechanism as well. However, intel_pstate is not modular and it
doesn't need the module refcount tricks played by
acpi_processor_notify_smm(), so export the core of this function
to it as acpi_processor_pstate_control() and make it call that.
[The changes in processor_perflib.c related to this should not
make any functional difference for the acpi_processor_notify_smm()
users].
To be safe, only call acpi_processor_notify_smm() from intel_pstate
if ACPI _PPC support is enabled in it.
Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Use get_target_pstate_use_cpu_load() to calculate target P-State for
devices, with the preferred power management profile in ACPI FADT
set to PM_MOBILE.
This may help in resolving some thermal issues caused by low sustained
cpu bound workloads. The current algorithm tend to over provision in this
case as it doesn't look at the CPU busyness.
Also included the fix from Arnd Bergmann <arnd@arndb.de> to solve compile
issue, when CONFIG_ACPI is not defined.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The limits variable gets modified from intel_pstate sysfs and also gets
modified from cpufreq sysfs. So protect with a mutex to keep data
integrity, when they are getting modified from multiple threads.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When policy->max and policy->min are same, in some cases they don't
result in the same frequency cap. The max_policy_pct is rounded up but
not min_perf_pct. So even when they are same, results in different
percentage or maximum and minimum.
Since minimum is a conservative value for power, a lower value without
rounding is better in most of the cases, unless user wants
policy->max = policy->min.
This change uses use the same policy percentage when policy->max and
policy->min are same.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Intel P-State offers two interface to set performance limits:
- Intel P-State sysfs
/sys/devices/system/cpu/intel_pstate/max_perf_pct
/sys/devices/system/cpu/intel_pstate/min_perf_pct
- cpufreq
/sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
In the current implementation both of the above methods, change limits
to every CPU in the system. Moreover the limits placed using cpufreq
policy interface also presented in the Intel P-State sysfs via modified
max_perf_pct and min_per_pct during sysfs reads. This allows to check
percent of reduced/increased performance, irrespective of method used to
limit.
There are some new generations of processors, where it is possible to
have limits placed on individual CPU cores. Using cpufreq interface it
is possible to set limits on each CPU. But the current processing will
use last limits placed on all CPUs. So the per core limit feature of
CPUs can't be used.
This change brings in capability to set P-States limits for each CPU,
with some limitations. In this case what should be the read of
max_perf_pct and min_perf_pct? It can be most restrictive limits placed
on any CPU or max possible performance on any given CPU on which no
limits are placed. In either case someone will have issue.
So the consensus is, we can't have both sysfs controls present when user
wants to use limit per core limits.
- By default per-core-control feature is not enabled. So no one will
notice any difference.
- The way to enable is by kernel command line
intel_pstate=per_cpu_perf_limits
- When the per-core-controls are enabled there is no display of for both
read and write on
/sys/devices/system/cpu/intel_pstate/max_perf_pct
/sys/devices/system/cpu/intel_pstate/min_perf_pct
- User can change limits using
/sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
/sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
- User can still observe turbo percent and number of P-States from
/sys/devices/system/cpu/intel_pstate/turbo_pct
/sys/devices/system/cpu/intel_pstate/num_pstates
- User can read write system wide turbo status
/sys/devices/system/cpu/no_turbo
While changing this BUG_ON is changed to WARN_ON, as they are not fatal
errors for the system.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Rafael J. Wysocki