Currently, ondemand calculates the target frequency proportional to load
using the formula:
	Target frequency = C * load
	where C = policy->cpuinfo.max_freq / 100

Though, in many cases, the minimum available frequency is pretty high and
the above calculation introduces a dead band from load 0 to
100 * policy->cpuinfo.min_freq / policy->cpuinfo.max_freq where the target
frequency is always calculated to less than policy->cpuinfo.min_freq and
the minimum frequency is selected.

For example: on Intel i7-3770 @ 3.4GHz the policy->cpuinfo.min_freq = 1600000
and the policy->cpuinfo.max_freq = 3400000 (without turbo). Thus, the CPU
starts to scale up at a load above 47.
On quad core 1500MHz Krait the policy->cpuinfo.min_freq = 384000
and the policy->cpuinfo.max_freq = 1512000. Thus, the CPU starts to scale
at load above 25.

Change the calculation of target frequency to eliminate the above effect using
the formula:

	Target frequency = A + B * load
	where A = policy->cpuinfo.min_freq and
	      B = (policy->cpuinfo.max_freq - policy->cpuinfo->min_freq) / 100

This will map load values 0 to 100 linearly to cpuinfo.min_freq to
cpuinfo.max_freq.

Also, use the CPUFREQ_RELATION_C in __cpufreq_driver_target to select the
closest frequency in frequency_table. This is necessary to avoid selection
of minimum frequency only when load equals to 0. It will also help for selection
of frequencies using a more 'fair' criterion.

Tables below show the difference in selected frequency for specific values
of load without and with this patch. On Intel i7-3770 @ 3.40GHz:
	Without			With
Load	Target	Selected	Target	Selected
0	0	1600000		1600000	1600000
5	170050	1600000		1690050	1700000
10	340100	1600000		1780100	1700000
15	510150	1600000		1870150	1900000
20	680200	1600000		1960200	2000000
25	850250	1600000		2050250	2100000
30	1020300	1600000		2140300	2100000
35	1190350	1600000		2230350	2200000
40	1360400	1600000		2320400	2400000
45	1530450	1600000		2410450	2400000
50	1700500	1900000		2500500	2500000
55	1870550	1900000		2590550	2600000
60	2040600	2100000		2680600	2600000
65	2210650	2400000		2770650	2800000
70	2380700	2400000		2860700	2800000
75	2550750	2600000		2950750	3000000
80	2720800	2800000		3040800	3000000
85	2890850	2900000		3130850	3100000
90	3060900	3100000		3220900	3300000
95	3230950	3300000		3310950	3300000
100	3401000	3401000		3401000	3401000

On ARM quad core 1500MHz Krait:
	Without			With
Load	Target	Selected	Target	Selected
0	0	384000		384000	384000
5	75600	384000		440400	486000
10	151200	384000		496800	486000
15	226800	384000		553200	594000
20	302400	384000		609600	594000
25	378000	384000		666000	702000
30	453600	486000		722400	702000
35	529200	594000		778800	810000
40	604800	702000		835200	810000
45	680400	702000		891600	918000
50	756000	810000		948000	918000
55	831600	918000		1004400	1026000
60	907200	918000		1060800	1026000
65	982800	1026000		1117200	1134000
70	1058400	1134000		1173600	1134000
75	1134000	1134000		1230000	1242000
80	1209600	1242000		1286400	1242000
85	1285200	1350000		1342800	1350000
90	1360800	1458000		1399200	1350000
95	1436400	1458000		1455600	1458000
100	1512000	1512000		1512000	1512000

Tested on Intel i7-3770 CPU @ 3.40GHz and on ARM quad core 1500MHz Krait
(Android smartphone).
Benchmarks on Intel i7 shows a performance improvement on low and medium
work loads with lower power consumption. Specifics:

Phoronix Linux Kernel Compilation 3.1:
Time: -0.40%, energy: -0.07%
Phoronix Apache:
Time: -4.98%, energy: -2.35%
Phoronix FFMPEG:
Time: -6.29%, energy: -4.02%

Also, running mp3 decoding (very low load) shows no differences with and
without this patch.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Introduce CPUFREQ_RELATION_C for frequency selection.
It selects the frequency with the minimum euclidean distance to target.
In case of equal distance between 2 frequencies, it will select the
greater frequency.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

PU regulator is not a necessary regulator for cpufreq, not all
i.MX6 SoCs have PU regulator, only if SOC has PU regulator, then its
voltage must be equal to SOC regulator, so remove the dependency
to support i.MX6SX which has no PU regulator.
Signed-off-by: Anson Huang <b20788@freescale.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The specific rounding adds conditionally only 1/256 to fractional
part of core_pct.

We can safely remove it without any noticeable impact in
calculations.

Use div64_u64 instead of div_u64 to avoid possible overflow of
sample->mperf as divisor
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Simplify the code by removing the inline functions pstate_increase and
pstate_decrease and use directly the intel_pstate_set_pstate.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Currently we shift right aperf and mperf variables by FRAC_BITS
to prevent overflow when we convert them to fix point numbers
(shift left by FRAC_BITS).

But this is not necessary, because we actually use delta aperf and mperf
which are much less than APERF and MPERF values.

So, use the unmodified APERF and MPERF values in calculation.
This also adds 8 bits in precision, although the gain is insignificant.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

According to Intel 64 and IA-32 Architectures SDM, Volume 3,
Chapter 14.2, "Software needs to exercise care to avoid delays
between the two RDMSRs (for example interrupts)".

So, disable interrupts during reading MSRs IA32_APERF and IA32_MPERF.
This should increase the accuracy of the calculations.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Suppress checkpatch.pl --strict warnings:
CHECK: Alignment should match open parenthesis
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Remove the unnecessary intermediate assignment and use directly the
pid_params.sample_rate_ms variable.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Remove unnecessary parentheses.
Also, add parentheses in one case for better readability.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

We can fit these lines in a single one, under the 80 characters
limit.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Also, remove unnecessary blank lines.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

div_s64() accepts the divisor parameter as s32. Helper div_fp()
also accepts divisor as int32_t.

So, remove the unnecessary int64_t type casting.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Since we never remove sysfs entry and debugfs files, we can make
the intel_pstate_kobject and debugfs_parent locals.

Also, annotate with __init intel_pstate_sysfs_expose_params()
and intel_pstate_debug_expose_params() in order to be freed
after bootstrap.
Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull more IIO driver fixes from Greg KH:
 "Here are two IIO driver fixes for 3.16-rc6 that resolve some reported
  issues"

* tag 'staging-3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  iio: mma8452: Use correct acceleration units.
  iio:core: Handle error when mask type is not separate

Pull USB fixes from Greg KH:
 "Here are two USB patches that resolve some reported issues, one with
  an odd HUB, and one in the chipidea driver"

* tag 'usb-3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: Check if port status is equal to RxDetect
  usb: chipidea: udc: Disable auto ZLP generation on ep0

Merge tag 'driver-core-3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fix from Greg KH:
 "Here is a single driver core fix that reverts an older patch that has
  been causing a number of reported problems with the platform devices.

  This revert has been in linux-next for a while with no reported issues"

* tag 'driver-core-3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  platform_get_irq: Revert to platform_get_resource if of_irq_get fails

Pull char/misc fix from Greg KH:
 "Here's a single hyper-v driver fix for a reported issue"

* tag 'char-misc-3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Drivers: hv: hv_fcopy: fix a race condition for SMP guest

Pull intel drm fixes from Dave Airlie:
 "Intel fixes came in late, but since I debugged one of them I'll send
  them on,

  Two reverts, a quirk and one warn regression"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  Revert "drm/i915: reverse dp link param selection, prefer fast over wide again"
  drm/i915: Track the primary plane correctly when reassigning planes
  drm/i915: Ignore VBT backlight presence check on HP Chromebook 14
  Revert "drm/i915: Don't set the 8to6 dither flag when not scaling"

Pull UML fixes from Richard Weinberger:
 "Four fixes, all discovered by Trinity"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: segv: Save regs only in case of a kernel mode fault
  um: Fix hung task in fix_range_common()
  um: Ensure that a stub page cannot get unmapped
  Revert "um: Fix wait_stub_done() error handling"

Pull btrfs fixes from Chris Mason:
 "We have two more fixes in my for-linus branch.

  I was hoping to also include a fix for a btrfs deadlock with
  compression enabled, but we're still nailing that one down"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  btrfs: test for valid bdev before kobj removal in btrfs_rm_device
  Btrfs: fix abnormal long waiting in fsync

Pull NFS client fixes from Trond Myklebust:
 "Apologies for the relative lateness of this pull request, however the
  commits fix some issues with the NFS read/write code updates in
  3.16-rc1 that can cause serious Oopsing when using small r/wsize.  The
  delay was mainly due to extra testing to make sure that the fixes
  behave correctly.

  Highlights include;
   - Stable fix for an NFSv3 posix ACL regression
   - Multiple fixes for regressions to the NFS generic read/write code:
     - Fix page splitting bugs that come into play when a small
       rsize/wsize read/write needs to be sent again (due to error
       conditions or page redirty)
     - Fix nfs_wb_page_cancel, which is called by the "invalidatepage"
       method
   - Fix 2 compile warnings about unused variables
   - Fix a performance issue affecting unstable writes"

* tag 'nfs-for-3.16-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: Don't reset pg_moreio in __nfs_pageio_add_request
  NFS: Remove 2 unused variables
  nfs: handle multiple reqs in nfs_wb_page_cancel
  nfs: handle multiple reqs in nfs_page_async_flush
  nfs: change find_request to find_head_request
  nfs: nfs_page should take a ref on the head req
  nfs: mark nfs_page reqs with flag for extra ref
  nfs: only show Posix ACLs in listxattr if actually present

...otherwise me lose user mode regs and the resulting
stack trace is useless.
Signed-off-by: Richard Weinberger <richard@nod.at>

If do_ops() fails we have to release current->mm->mmap_sem
otherwise the failing task will never terminate.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

Trinity discovered an execution path such that a task
can unmap his stub page.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

This reverts commit 0974a9ca.
The real for for that issue is to release current->mm->mmap_sem in
fix_range_common().
Signed-off-by: Richard Weinberger <richard@nod.at>

commit 99994cde btrfs: dev delete should remove sysfs entry
added a btrfs_kobj_rm_device, which dereferences device->bdev...
right after we check whether device->bdev might be NULL.

I don't honestly know if it's possible to have a NULL device->bdev
here, but assuming that it is (given the test), we need to move
the kobject removal to be under that test.

(Coverity spotted this)
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>

xfstests generic/127 detected this problem.

With commit 7fc34a62, now fsync will only flush
data within the passed range.  This is the cause of the above problem,
-- btrfs's fsync has a stage called 'sync log' which will wait for all the
ordered extents it've recorded to finish.

In xfstests/generic/127, with mixed operations such as truncate, fallocate,
punch hole, and mapwrite, we get some pre-allocated extents, and mapwrite will
mmap, and then msync.  And I find that msync will wait for quite a long time
(about 20s in my case), thanks to ftrace, it turns out that the previous
fallocate calls 'btrfs_wait_ordered_range()' to flush dirty pages, but as the
range of dirty pages may be larger than 'btrfs_wait_ordered_range()' wants,
there can be some ordered extents created but not getting corresponding pages
flushed, then they're left in memory until we fsync which runs into the
stage 'sync log', and fsync will just wait for the system writeback thread
to flush those pages and get ordered extents finished, so the latency is
inevitable.

This adds a flush similar to btrfs_start_ordered_extent() in
btrfs_wait_logged_extents() to fix that.
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>

Pull locking fixes from Thomas Gleixner:
 "The locking department delivers:

   - A rather large and intrusive bundle of fixes to address serious
     performance regressions introduced by the new rwsem / mcs
     technology.  Simpler solutions have been discussed, but they would
     have been ugly bandaids with more risk than doing the right thing.

   - Make the rwsem spin on owner technology opt-in for architectures
     and enable it only on the known to work ones.

   - A few fixes to the lockdep userspace library"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Add CONFIG_RWSEM_SPIN_ON_OWNER
  locking/mutex: Disable optimistic spinning on some architectures
  locking/rwsem: Reduce the size of struct rw_semaphore
  locking/rwsem: Rename 'activity' to 'count'
  locking/spinlocks/mcs: Micro-optimize osq_unlock()
  locking/spinlocks/mcs: Introduce and use init macro and function for osq locks
  locking/spinlocks/mcs: Convert osq lock to atomic_t to reduce overhead
  locking/spinlocks/mcs: Rename optimistic_spin_queue() to optimistic_spin_node()
  locking/rwsem: Allow conservative optimistic spinning when readers have lock
  tools/liblockdep: Account for bitfield changes in lockdeps lock_acquire
  tools/liblockdep: Remove debug print left over from development
  tools/liblockdep: Fix comparison of a boolean value with a value of 2

Pull scheduler fix from Thomas Gleixner:
 "Prevent a possible divide by zero in the debugging code"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix possible divide by zero in avg_atom() calculation

Pull irq fixes from Thomas Gleixner:
 "Three patches addressing shortcomings in the ARM gic interrupt chip
  driver"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip: gic: Fix core ID calculation when topology is read from DT
  irqchip: gic: Add binding probe for ARM GIC400
  irqchip: gic: Add support for cortex a7 compatible string

Pull timer fix from Thomas Gleixner:
 "A single fix for a long standing issue in the alarm timer subsystem,
  which was noticed recently when people finally started to use alarm
  timers for serious work"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  alarmtimer: Fix bug where relative alarm timers were treated as absolute

Pull RCU fixes from Thomas Gleixner:
 "Two RCU patches:
   - Address a serious performance regression on open/close caused by
     commit ac1bea85 ("Make cond_resched() report RCU quiescent
     states")
   - Export RCU debug functions.  Not a regression, but enablement to
     address a serious recursion bug in the sl*b allocators in 3.17"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Reduce overhead of cond_resched() checks for RCU
  rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()

Pull ARM SoC fixes from Olof Johansson:
 "A smaller set of fixes this week, and all regression fixes:
   - a handful of issues fixed on at91 with common clock conversion
   - a set of fixes for Marvell mvebu (SMP, coherency, PM)
   - a clock fix for i.MX6Q.
   - ... and a SMP/hotplug fix for Exynos"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: EXYNOS: Fix core ID used by platsmp and hotplug code
  ARM: at91/dt: add missing clocks property to pwm node in sam9x5.dtsi
  ARM: at91/dt: fix usb0 clocks definition in sam9n12 dtsi
  ARM: at91: at91sam9x5: correct typo error for ohci clock
  ARM: clk-imx6q: parent lvds_sel input from upstream clock gates
  ARM: mvebu: Fix coherency bus notifiers by using separate notifiers
  ARM: mvebu: Fix the operand list in the inline asm of armada_370_xp_pmsu_idle_enter
  ARM: mvebu: fix SMP boot for Armada 38x and Armada 375 Z1 in big endian

But in any case nothing really shocking in
here, 2 reverts, 1 quirk and a regression fix a WARN.

* tag 'drm-intel-fixes-2014-07-18' of git://anongit.freedesktop.org/drm-intel:
  Revert "drm/i915: reverse dp link param selection, prefer fast over wide again"
  drm/i915: Track the primary plane correctly when reassigning planes
  drm/i915: Ignore VBT backlight presence check on HP Chromebook 14
  Revert "drm/i915: Don't set the 8to6 dither flag when not scaling"

Pull x86 fixes from Peter Anvin:
 "A couple of key fixes and a few less critical ones.  The main ones
  are:

   - add a .bss section to the PE/COFF headers when building with EFI
     stub

   - invoke the correct paravirt magic when building the espfix page
     tables

  Unfortunately both of these areas also have at least one additional
  fix each still in thie pipeline, but which are not yet ready to push"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Remove unused variable "polling"
  x86/espfix/xen: Fix allocation of pages for paravirt page tables
  x86/efi: Include a .bss section within the PE/COFF headers
  efi: fdt: Do not report an error during boot if UEFI is not available
  efi/arm64: efistub: remove local copy of linux_banner

Pull infiniband/rdma fixes from Roland Dreier:
 - cxgb4 hardware driver regression fixes
 - mlx5 hardware driver regression fixes

* tag 'rdma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  IB/mlx5: Enable "block multicast loopback" for kernel consumers
  RDMA/cxgb4: Call iwpm_init() only once
  mlx5_core: Fix possible race between mr tree insert/delete
  RDMA/cxgb4: Initialize the device status page
  RDMA/cxgb4: Clean up connection on ARP error
  RDMA/cxgb4: Fix skb_leak in reject_cr()

Pull hwmon fixes from Guenter Roeck:
 "More fallout from module tests and code inspection.

  Fixes to temperature limit write operations in adt7470 driver.  Also,
  dashes are not allowed in hwmon 'name' attributes.  Fix drivers where
  necessary"

* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (adt7470) Fix writes to temperature limit registers
  hwmon: (da9055) Don't use dash in the name attribute
  hwmon: (da9052) Don't use dash in the name attribute

Pull iommu fixes from Joerg Roedel:
 "A couple of fixes for the Freescale PAMU driver queued up:

   - fix PAMU window size check.
   - fix the device domain attach condition.
   - fix the error condition during iommu group"

* tag 'iommu-fixes-v3.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/fsl: Fix the error condition during iommu group
  iommu/fsl: Fix the device domain attach condition.
  iommu/fsl: Fix PAMU window size check.