Add description of timer_rate tunable and clean up some
typos.

Change-Id: I4b96a36aad51eed3bef0ee5f571dc6e0a94c8dd9
Signed-off-by: Allen Martin <amartin@nvidia.com>

Fixes a checkpatch warning

Change-Id: I2962b7c32f336188de0d2fe4f0f13f1199cb68e2
Signed-off-by: Allen Martin <amartin@nvidia.com>

This governor is designed for latency-sensitive workloads, such as
interactive user interfaces.  The interactive governor aims to be
significantly more responsive to ramp CPU quickly up when CPU-intensive
activity begins.

Existing governors sample CPU load at a particular rate, typically
every X ms.  This can lead to under-powering UI threads for the period of
time during which the user begins interacting with a previously-idle system
until the next sample period happens.

The 'interactive' governor uses a different approach. Instead of sampling
the CPU at a specified rate, the governor will check whether to scale the
CPU frequency up soon after coming out of idle.  When the CPU comes out of
idle, a timer is configured to fire within 1-2 ticks.  If the CPU is very
busy from exiting idle to when the timer fires then we assume the CPU is
underpowered and ramp to MAX speed.

If the CPU was not sufficiently busy to immediately ramp to MAX speed, then
the governor evaluates the CPU load since the last speed adjustment,
choosing the highest value between that longer-term load or the short-term
load since idle exit to determine the CPU speed to ramp to.

A realtime thread is used for scaling up, giving the remaining tasks the
CPU performance benefit, unlike existing governors which are more likely to
schedule rampup work to occur after your performance starved tasks have
completed.

The tuneables for this governor are:
/sys/devices/system/cpu/cpufreq/interactive/min_sample_time:
	The minimum amount of time to spend at the current frequency before
	ramping down. This is to ensure that the governor has seen enough
	historic CPU load data to determine the appropriate workload.
	Default is 80000 uS.
/sys/devices/system/cpu/cpufreq/interactive/go_maxspeed_load
	The CPU load at which to ramp to max speed.  Default is 85.

Change-Id: Ib2b362607c62f7c56d35f44a9ef3280f98c17585
Signed-off-by: Mike Chan <mike@android.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Bug: 3152864

Change all "arch/i386" to "arch/x86" in Documentaion/,
since the directory has changed.

Also update the files which have changed their filename
in the meantime accordingly.

Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
[jkosina@suse.cz: reword changelog]
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Update cpufreq governor documentation for sampling_down_factor tunable
parameter.

Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Dave Jones <davej@redhat.com>

Processor Clocking Control (PCC) is an interface between the BIOS and OSPM.
Based on the server workload, OSPM can request what frequency it expects
from a logical CPU, and the BIOS will achieve that frequency transparently.

This patch introduces driver support for PCC. OSPM uses the PCC driver to
communicate with the BIOS via the PCC interface.

There is a Documentation file that provides a link to the PCC
Specification, and also provides a summary of the PCC interface.

Currently, certain HP ProLiant platforms implement the PCC interface. However,
any platform whose BIOS implements the PCC Specification, can utilize this
driver.

V2 --> V1 changes (based on Dominik's suggestions):
- Removed the dependency on CPU_FREQ_TABLE
- "cpufreq_stats" will no longer PANIC. Actually, it will not load anymore
because it is not applicable.
- Removed the sanity check for target frequency in the ->target routine.

NOTE: A patch to sanitize the target frequency requested by "ondemand" is
needed to ensure that the target freq < policy->min.

Can this driver be queued up for the 2.6.33 tree?

Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Dave Jones <davej@redhat.com>

This interface is mainly intended (and implemented) for ACPI _PPC BIOS
frequency limitations, but other cpufreq drivers can also use it for
similar use-cases.

Why is this needed:

Currently it's not obvious why cpufreq got limited.
People see cpufreq/scaling_max_freq reduced, but this could have
happened by:
  - any userspace prog writing to scaling_max_freq
  - thermal limitations
  - hardware (_PPC in ACPI case) limitiations

Therefore export bios_limit (in kHz) to:
  - Point the user that it's the BIOS (broken or intended) which limits
    frequency
  - Export it as a sysfs interface for userspace progs.
    While this was a rarely used feature on laptops, there will appear
    more and more server implemenations providing "Green IT" features like
    allowing the service processor to limit the frequency. People want
    to know about HW/BIOS frequency limitations.

All ACPI P-state driven cpufreq drivers are covered with this patch:
  - powernow-k8
  - powernow-k7
  - acpi-cpufreq

Tested with a patched DSDT which limits the first two cores (_PPC returns 1)
via _PPC, exposed by bios_limit:
# echo 2200000 >cpu2/cpufreq/scaling_max_freq
# cat cpu*/cpufreq/scaling_max_freq
2600000
2600000
2200000
2200000
# #scaling_max_freq shows general user/thermal/BIOS limitations

# cat cpu*/cpufreq/bios_limit
2600000
2600000
2800000
2800000
# #bios_limit only shows the HW/BIOS limitation

CC: Pallipadi Venkatesh <venkatesh.pallipadi@intel.com>
CC: Len Brown <lenb@kernel.org>
CC: davej@codemonkey.org.uk
CC: linux@dominikbrodowski.net

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

They're documented in the header but not in Documentation.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dave Jones <davej@redhat.com>

I think the way "cpuinfo_cur_info" and "scaling_cur_info" are defined under
./Documentation/cpu-freq/user-guide.txt can be enhanced. Currently, they are
both defined the same way: "Current speed/frequency" of the CPU, in KHz".

Below is a patch that distinguishes one from the other.

Regards,
- naga -

-----------------------------------------
Update description for "cpuinfo_cur_freq" and "scaling_cur_freq".

Some of the wording is drawn from comments found in
./drivers/cpufreq/cpufreq.c: cpufreq_out_of_sync():

 *      @old_freq: CPU frequency the kernel thinks the CPU runs at
 *      @new_freq: CPU frequency the CPU actually runs at

Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Dave Jones <davej@redhat.com>