<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/cpufreq/intel_pstate.c, branch v4.20</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>cpufreq: intel_pstate: Fix compilation for !CONFIG_ACPI</title>
<updated>2018-10-25T16:37:06+00:00</updated>
<author>
<name>Dominik Brodowski</name>
<email>linux@dominikbrodowski.net</email>
</author>
<published>2018-10-23T19:54:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5906056e52e9ee5e130d880443e83016f892b5dd'/>
<id>5906056e52e9ee5e130d880443e83016f892b5dd</id>
<content type='text'>
While at it, add a few comments which config options #ifdef
and #else statements refer to.

Fixes: 86d333a8cc7f (cpufreq: intel_pstate: Add base_frequency attribute)
Signed-off-by: Dominik Brodowski &lt;linux@dominikbrodowski.net&gt;
Acked-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
While at it, add a few comments which config options #ifdef
and #else statements refer to.

Fixes: 86d333a8cc7f (cpufreq: intel_pstate: Add base_frequency attribute)
Signed-off-by: Dominik Brodowski &lt;linux@dominikbrodowski.net&gt;
Acked-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2018-10-23T12:32:18+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-10-23T12:32:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c05f3642f4304dd081876e77a68555b6aba4483f'/>
<id>c05f3642f4304dd081876e77a68555b6aba4483f</id>
<content type='text'>
Pull perf updates from Ingo Molnar:
 "The main updates in this cycle were:

   - Lots of perf tooling changes too voluminous to list (big perf trace
     and perf stat improvements, lots of libtraceevent reorganization,
     etc.), so I'll list the authors and refer to the changelog for
     details:

       Benjamin Peterson, Jérémie Galarneau, Kim Phillips, Peter
       Zijlstra, Ravi Bangoria, Sangwon Hong, Sean V Kelley, Steven
       Rostedt, Thomas Gleixner, Ding Xiang, Eduardo Habkost, Thomas
       Richter, Andi Kleen, Sanskriti Sharma, Adrian Hunter, Tzvetomir
       Stoyanov, Arnaldo Carvalho de Melo, Jiri Olsa.

     ... with the bulk of the changes written by Jiri Olsa, Tzvetomir
     Stoyanov and Arnaldo Carvalho de Melo.

   - Continued intel_rdt work with a focus on playing well with perf
     events. This also imported some non-perf RDT work due to
     dependencies. (Reinette Chatre)

   - Implement counter freezing for Arch Perfmon v4 (Skylake and newer).
     This allows to speed up the PMI handler by avoiding unnecessary MSR
     writes and make it more accurate. (Andi Kleen)

   - kprobes cleanups and simplification (Masami Hiramatsu)

   - Intel Goldmont PMU updates (Kan Liang)

   - ... plus misc other fixes and updates"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (155 commits)
  kprobes/x86: Use preempt_enable() in optimized_callback()
  x86/intel_rdt: Prevent pseudo-locking from using stale pointers
  kprobes, x86/ptrace.h: Make regs_get_kernel_stack_nth() not fault on bad stack
  perf/x86/intel: Export mem events only if there's PEBS support
  x86/cpu: Drop pointless static qualifier in punit_dev_state_show()
  x86/intel_rdt: Fix initial allocation to consider CDP
  x86/intel_rdt: CBM overlap should also check for overlap with CDP peer
  x86/intel_rdt: Introduce utility to obtain CDP peer
  tools lib traceevent, perf tools: Move struct tep_handler definition in a local header file
  tools lib traceevent: Separate out tep_strerror() for strerror_r() issues
  perf python: More portable way to make CFLAGS work with clang
  perf python: Make clang_has_option() work on Python 3
  perf tools: Free temporary 'sys' string in read_event_files()
  perf tools: Avoid double free in read_event_file()
  perf tools: Free 'printk' string in parse_ftrace_printk()
  perf tools: Cleanup trace-event-info 'tdata' leak
  perf strbuf: Match va_{add,copy} with va_end
  perf test: S390 does not support watchpoints in test 22
  perf auxtrace: Include missing asm/bitsperlong.h to get BITS_PER_LONG
  tools include: Adopt linux/bits.h
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull perf updates from Ingo Molnar:
 "The main updates in this cycle were:

   - Lots of perf tooling changes too voluminous to list (big perf trace
     and perf stat improvements, lots of libtraceevent reorganization,
     etc.), so I'll list the authors and refer to the changelog for
     details:

       Benjamin Peterson, Jérémie Galarneau, Kim Phillips, Peter
       Zijlstra, Ravi Bangoria, Sangwon Hong, Sean V Kelley, Steven
       Rostedt, Thomas Gleixner, Ding Xiang, Eduardo Habkost, Thomas
       Richter, Andi Kleen, Sanskriti Sharma, Adrian Hunter, Tzvetomir
       Stoyanov, Arnaldo Carvalho de Melo, Jiri Olsa.

     ... with the bulk of the changes written by Jiri Olsa, Tzvetomir
     Stoyanov and Arnaldo Carvalho de Melo.

   - Continued intel_rdt work with a focus on playing well with perf
     events. This also imported some non-perf RDT work due to
     dependencies. (Reinette Chatre)

   - Implement counter freezing for Arch Perfmon v4 (Skylake and newer).
     This allows to speed up the PMI handler by avoiding unnecessary MSR
     writes and make it more accurate. (Andi Kleen)

   - kprobes cleanups and simplification (Masami Hiramatsu)

   - Intel Goldmont PMU updates (Kan Liang)

   - ... plus misc other fixes and updates"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (155 commits)
  kprobes/x86: Use preempt_enable() in optimized_callback()
  x86/intel_rdt: Prevent pseudo-locking from using stale pointers
  kprobes, x86/ptrace.h: Make regs_get_kernel_stack_nth() not fault on bad stack
  perf/x86/intel: Export mem events only if there's PEBS support
  x86/cpu: Drop pointless static qualifier in punit_dev_state_show()
  x86/intel_rdt: Fix initial allocation to consider CDP
  x86/intel_rdt: CBM overlap should also check for overlap with CDP peer
  x86/intel_rdt: Introduce utility to obtain CDP peer
  tools lib traceevent, perf tools: Move struct tep_handler definition in a local header file
  tools lib traceevent: Separate out tep_strerror() for strerror_r() issues
  perf python: More portable way to make CFLAGS work with clang
  perf python: Make clang_has_option() work on Python 3
  perf tools: Free temporary 'sys' string in read_event_files()
  perf tools: Avoid double free in read_event_file()
  perf tools: Free 'printk' string in parse_ftrace_printk()
  perf tools: Cleanup trace-event-info 'tdata' leak
  perf strbuf: Match va_{add,copy} with va_end
  perf test: S390 does not support watchpoints in test 22
  perf auxtrace: Include missing asm/bitsperlong.h to get BITS_PER_LONG
  tools include: Adopt linux/bits.h
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Add base_frequency attribute</title>
<updated>2018-10-16T08:33:39+00:00</updated>
<author>
<name>Srinivas Pandruvada</name>
<email>srinivas.pandruvada@linux.intel.com</email>
</author>
<published>2018-10-15T17:37:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=86d333a8cc7f66c2314ab1e147834a1cd95ec2de'/>
<id>86d333a8cc7f66c2314ab1e147834a1cd95ec2de</id>
<content type='text'>
Expose base_frequency to user space via cpufreq sysfs when HWP is in
use.

This HWP base frequency is read from the ACPI _CPC object if present,
or from the HWP Capabilities MSR otherwise.

On the majority of the HWP platforms the _CPC object will point to
the HWP Capabilities MSR using the "Functional Fixed Hardware"
address space type.  The address space type also can simply be
ACPI_TYPE_INTEGER, however, in which case the platform firmware
can set its value at the initialization time based on the system
constraints.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Expose base_frequency to user space via cpufreq sysfs when HWP is in
use.

This HWP base frequency is read from the ACPI _CPC object if present,
or from the HWP Capabilities MSR otherwise.

On the majority of the HWP platforms the _CPC object will point to
the HWP Capabilities MSR using the "Functional Fixed Hardware"
address space type.  The address space type also can simply be
ACPI_TYPE_INTEGER, however, in which case the platform firmware
can set its value at the initialization time based on the system
constraints.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/cpu: Sanitize FAM6_ATOM naming</title>
<updated>2018-10-02T08:14:32+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2018-08-07T17:17:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f2c4db1bd80720cd8cb2a5aa220d9bc9f374f04e'/>
<id>f2c4db1bd80720cd8cb2a5aa220d9bc9f374f04e</id>
<content type='text'>
Going primarily by:

  https://en.wikipedia.org/wiki/List_of_Intel_Atom_microprocessors

with additional information gleaned from other related pages; notably:

 - Bonnell shrink was called Saltwell
 - Moorefield is the Merriefield refresh which makes it Airmont

The general naming scheme is: FAM6_ATOM_UARCH_SOCTYPE

  for i in `git grep -l FAM6_ATOM` ; do
	sed -i  -e 's/ATOM_PINEVIEW/ATOM_BONNELL/g'		\
		-e 's/ATOM_LINCROFT/ATOM_BONNELL_MID/'		\
		-e 's/ATOM_PENWELL/ATOM_SALTWELL_MID/g'		\
		-e 's/ATOM_CLOVERVIEW/ATOM_SALTWELL_TABLET/g'	\
		-e 's/ATOM_CEDARVIEW/ATOM_SALTWELL/g'		\
		-e 's/ATOM_SILVERMONT1/ATOM_SILVERMONT/g'	\
		-e 's/ATOM_SILVERMONT2/ATOM_SILVERMONT_X/g'	\
		-e 's/ATOM_MERRIFIELD/ATOM_SILVERMONT_MID/g'	\
		-e 's/ATOM_MOOREFIELD/ATOM_AIRMONT_MID/g'	\
		-e 's/ATOM_DENVERTON/ATOM_GOLDMONT_X/g'		\
		-e 's/ATOM_GEMINI_LAKE/ATOM_GOLDMONT_PLUS/g' ${i}
  done

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Cc: dave.hansen@linux.intel.com
Cc: len.brown@intel.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Going primarily by:

  https://en.wikipedia.org/wiki/List_of_Intel_Atom_microprocessors

with additional information gleaned from other related pages; notably:

 - Bonnell shrink was called Saltwell
 - Moorefield is the Merriefield refresh which makes it Airmont

The general naming scheme is: FAM6_ATOM_UARCH_SOCTYPE

  for i in `git grep -l FAM6_ATOM` ; do
	sed -i  -e 's/ATOM_PINEVIEW/ATOM_BONNELL/g'		\
		-e 's/ATOM_LINCROFT/ATOM_BONNELL_MID/'		\
		-e 's/ATOM_PENWELL/ATOM_SALTWELL_MID/g'		\
		-e 's/ATOM_CLOVERVIEW/ATOM_SALTWELL_TABLET/g'	\
		-e 's/ATOM_CEDARVIEW/ATOM_SALTWELL/g'		\
		-e 's/ATOM_SILVERMONT1/ATOM_SILVERMONT/g'	\
		-e 's/ATOM_SILVERMONT2/ATOM_SILVERMONT_X/g'	\
		-e 's/ATOM_MERRIFIELD/ATOM_SILVERMONT_MID/g'	\
		-e 's/ATOM_MOOREFIELD/ATOM_AIRMONT_MID/g'	\
		-e 's/ATOM_DENVERTON/ATOM_GOLDMONT_X/g'		\
		-e 's/ATOM_GEMINI_LAKE/ATOM_GOLDMONT_PLUS/g' ${i}
  done

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Cc: dave.hansen@linux.intel.com
Cc: len.brown@intel.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Ignore turbo active ratio in HWP</title>
<updated>2018-08-06T08:22:27+00:00</updated>
<author>
<name>Srinivas Pandruvada</name>
<email>srinivas.pandruvada@linux.intel.com</email>
</author>
<published>2018-08-02T00:26:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d3264f752a1aedac98aa90e50853df149d1346f2'/>
<id>d3264f752a1aedac98aa90e50853df149d1346f2</id>
<content type='text'>
When HWP is active turbo active ratio is not used, so we should allow
policy max frequency above turbo activation ratio to be set. When HWP is
not active, then any policy max frequency above turbo activation ratio
can result upto max one-core turbo frequency.

This fix helps better thermal control in turbo region when other methods
like "Running Average Power Limit" is not available to use.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When HWP is active turbo active ratio is not used, so we should allow
policy max frequency above turbo activation ratio to be set. When HWP is
not active, then any policy max frequency above turbo activation ratio
can result upto max one-core turbo frequency.

This fix helps better thermal control in turbo region when other methods
like "Running Average Power Limit" is not available to use.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge back cpufreq changes for 4.19.</title>
<updated>2018-08-06T08:09:52+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2018-08-06T08:09:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6ccbe1dcdd17c9b76cc9f63e2dc600b381cb2378'/>
<id>6ccbe1dcdd17c9b76cc9f63e2dc600b381cb2378</id>
<content type='text'>
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Limit the scope of HWP dynamic boost platforms</title>
<updated>2018-07-31T08:39:58+00:00</updated>
<author>
<name>Srinivas Pandruvada</name>
<email>srinivas.pandruvada@linux.intel.com</email>
</author>
<published>2018-07-30T22:00:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=01e61a42a5d345a4c0205889498f0c9a0fb9ee8c'/>
<id>01e61a42a5d345a4c0205889498f0c9a0fb9ee8c</id>
<content type='text'>
Dynamic boosting of HWP performance on IO wake showed significant
improvement to IO workloads. This series was intended for Skylake Xeon
platforms only and feature was enabled by default based on CPU model
number.

But some Xeon platforms reused the Skylake desktop CPU model number. This
caused some undesirable side effects to some graphics workloads. Since
they are heavily IO bound, the increase in CPU performance decreased the
power available for GPU to do its computing and hence decrease in graphics
benchmark performance.

For example on a Skylake desktop, GpuTest benchmark showed average FPS
reduction from 529 to 506.

This change makes sure that HWP boost feature is only enabled for Skylake
server platforms by using ACPI FADT preferred PM Profile. If some desktop
users wants to get benefit of boost, they can still enable boost from
intel_pstate sysfs attribute "hwp_dynamic_boost".

Fixes: 41ab43c9c89e (cpufreq: intel_pstate: enable boost for Skylake Xeon)
Link: https://bugs.freedesktop.org/show_bug.cgi?id=107410
Reported-by: Eero Tamminen &lt;eero.t.tamminen@intel.com&gt;
Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Reviewed-by: Francisco Jerez &lt;currojerez@riseup.net&gt;
Acked-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Dynamic boosting of HWP performance on IO wake showed significant
improvement to IO workloads. This series was intended for Skylake Xeon
platforms only and feature was enabled by default based on CPU model
number.

But some Xeon platforms reused the Skylake desktop CPU model number. This
caused some undesirable side effects to some graphics workloads. Since
they are heavily IO bound, the increase in CPU performance decreased the
power available for GPU to do its computing and hence decrease in graphics
benchmark performance.

For example on a Skylake desktop, GpuTest benchmark showed average FPS
reduction from 529 to 506.

This change makes sure that HWP boost feature is only enabled for Skylake
server platforms by using ACPI FADT preferred PM Profile. If some desktop
users wants to get benefit of boost, they can still enable boost from
intel_pstate sysfs attribute "hwp_dynamic_boost".

Fixes: 41ab43c9c89e (cpufreq: intel_pstate: enable boost for Skylake Xeon)
Link: https://bugs.freedesktop.org/show_bug.cgi?id=107410
Reported-by: Eero Tamminen &lt;eero.t.tamminen@intel.com&gt;
Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Reviewed-by: Francisco Jerez &lt;currojerez@riseup.net&gt;
Acked-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge back cpufreq material for 4.19.</title>
<updated>2018-07-25T11:28:01+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2018-07-25T11:28:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6e926363fc0071e6dc33349dedd97f28e9a2e464'/>
<id>6e926363fc0071e6dc33349dedd97f28e9a2e464</id>
<content type='text'>
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Show different max frequency with turbo 3 and HWP</title>
<updated>2018-07-19T10:53:03+00:00</updated>
<author>
<name>Srinivas Pandruvada</name>
<email>srinivas.pandruvada@linux.intel.com</email>
</author>
<published>2018-07-18T21:51:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=eea033d07543a177fc2ab35a6d633b2aa9684b0f'/>
<id>eea033d07543a177fc2ab35a6d633b2aa9684b0f</id>
<content type='text'>
On HWP platforms with Turbo 3.0, the HWP capability max ratio shows the
maximum ratio of that core, which can be different than other cores. If
we show the correct maximum frequency in cpufreq sysfs via
cpuinfo_max_freq and scaling_max_freq then, user can know which cores
can run faster for pinning some high priority tasks.

Currently the max turbo frequency is shown as max frequency, which is
the max of all cores, even if some cores can't reach that frequency
even for single threaded workload.

But it is possible that max ratio in HWP capabilities is set as 0xFF or
some high invalid value (E.g. One KBL NUC). Since the actual performance
can never exceed 1 core turbo frequency from MSR TURBO_RATIO_LIMIT, we
use this as a bound check.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On HWP platforms with Turbo 3.0, the HWP capability max ratio shows the
maximum ratio of that core, which can be different than other cores. If
we show the correct maximum frequency in cpufreq sysfs via
cpuinfo_max_freq and scaling_max_freq then, user can know which cores
can run faster for pinning some high priority tasks.

Currently the max turbo frequency is shown as max frequency, which is
the max of all cores, even if some cores can't reach that frequency
even for single threaded workload.

But it is possible that max ratio in HWP capabilities is set as 0xFF or
some high invalid value (E.g. One KBL NUC). Since the actual performance
can never exceed 1 core turbo frequency from MSR TURBO_RATIO_LIMIT, we
use this as a bound check.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Register when ACPI PCCH is present</title>
<updated>2018-07-18T11:38:37+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2018-07-18T11:38:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=95d6c0857e54b788982746071130d822a795026b'/>
<id>95d6c0857e54b788982746071130d822a795026b</id>
<content type='text'>
Currently, intel_pstate doesn't register if _PSS is not present on
HP Proliant systems, because it expects the firmware to take over
CPU performance scaling in that case.  However, if ACPI PCCH is
present, the firmware expects the kernel to use it for CPU
performance scaling and the pcc-cpufreq driver is loaded for that.

Unfortunately, the firmware interface used by that driver is not
scalable for fundamental reasons, so pcc-cpufreq is way suboptimal
on systems with more than just a few CPUs.  In fact, it is better to
avoid using it at all.

For this reason, modify intel_pstate to look for ACPI PCCH if _PSS
is not present and register if it is there.  Also prevent the
pcc-cpufreq driver from trying to initialize itself if intel_pstate
has been registered already.

Fixes: fbbcdc0744da (intel_pstate: skip the driver if ACPI has power mgmt option)
Reported-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Reviewed-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Acked-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Tested-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Cc: 4.16+ &lt;stable@vger.kernel.org&gt; # 4.16+
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, intel_pstate doesn't register if _PSS is not present on
HP Proliant systems, because it expects the firmware to take over
CPU performance scaling in that case.  However, if ACPI PCCH is
present, the firmware expects the kernel to use it for CPU
performance scaling and the pcc-cpufreq driver is loaded for that.

Unfortunately, the firmware interface used by that driver is not
scalable for fundamental reasons, so pcc-cpufreq is way suboptimal
on systems with more than just a few CPUs.  In fact, it is better to
avoid using it at all.

For this reason, modify intel_pstate to look for ACPI PCCH if _PSS
is not present and register if it is there.  Also prevent the
pcc-cpufreq driver from trying to initialize itself if intel_pstate
has been registered already.

Fixes: fbbcdc0744da (intel_pstate: skip the driver if ACPI has power mgmt option)
Reported-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Reviewed-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Acked-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Tested-by: Andreas Herrmann &lt;aherrmann@suse.com&gt;
Cc: 4.16+ &lt;stable@vger.kernel.org&gt; # 4.16+
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
