scheduler: compute time-average nr_running per run-queue

Compute the time-average number of running tasks per run-queue for a
trailing window of a fixed time period. The detla add/sub to the
average value is weighted by the amount of time per nr_running value
relative to the total measurement period.

Change-Id: I076e24ff4ed65bed3b8dd8d2b279a503318071ff
Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com>
(cherry picked from commit 3a12d7499cee352e8a46eaf700259ba3c733f0e3)
Reviewed-on: http://git-master/r/111635
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Tested-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
add'l commits on scheduler: compute time-average nr_running per run-queue
scheduler: Re-compute time-average nr_running on read Re-compute time-average nr_running when it is read. This would prevent reading stalled average value if there were no run-queue changes for a long time. New average value is returned to the reader, but not stored to avoid concurrent writes. Light-weight sequential counter synchronization is used to assure data consistency for re-computing average.

Change-Id: I8e4ea1b28ea00b3ddaf6ef7cdcd27866f87d360b
Signed-off-by: Alex Frid <afrid@nvidia.com>
(cherry picked from commit 527a759)
Reviewed-on: http://git-master/r/111637
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Tested-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>
ARM: move VFP init to an earlier boot stage

In order to use the NEON unit in the kernel, we should
initialize it a bit earlier in the boot process so NEON users
that like to do a quick benchmark at load time (like the
xor_blocks or RAID-6 code) find the NEON/VFP unit already
enabled.

Replaced late_initcall() with core_initcall().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>

Conflicts:
	arch/arm/vfp/vfpmodule.c
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
ARM: be strict about FP exceptions in kernel mode

The support code in vfp_support_entry does not care whether the
exception that caused it to be invoked occurred in kernel mode or
in user mode. However, neither condition that could trigger this
exception (lazy restore and VFP bounce to support code) is
currently allowable in kernel mode.

In either case, print a message describing the condition before
letting the undefined instruction handler run its course and trigger
an oops.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>

Conflicts:
	arch/arm/vfp/vfpmodule.c
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
ARM: add support for kernel mode NEON

In order to safely support the use of NEON instructions in
kernel mode, some precautions need to be taken:
- the userland context that may be present in the registers (even
  if the NEON/VFP is currently disabled) must be stored under the
  correct task (which may not be 'current' in the UP case),
- to avoid having to keep track of additional vfpstates for the
  kernel side, disallow the use of NEON in interrupt context
  and run with preemption disabled,
- after use, re-enable preemption and re-enable the lazy restore
  machinery by disabling the NEON/VFP unit.

This patch adds the functions kernel_neon_begin() and
kernel_neon_end() which take care of the above. It also adds
the Kconfig symbol KERNEL_MODE_NEON to enable it.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>

Conflicts:
	arch/arm/vfp/vfpmodule.c
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
ARM: add support for kernel mode NEON

In order to safely support the use of NEON instructions in
kernel mode, some precautions need to be taken:
- the userland context that may be present in the registers (even
  if the NEON/VFP is currently disabled) must be stored under the
  correct task (which may not be 'current' in the UP case),
- to avoid having to keep track of additional vfpstates for the
  kernel side, disallow the use of NEON in interrupt context
  and run with preemption disabled,
- after use, re-enable preemption and re-enable the lazy restore
  machinery by disabling the NEON/VFP unit.

This patch adds the functions kernel_neon_begin() and
kernel_neon_end() which take care of the above. It also adds
the Kconfig symbol KERNEL_MODE_NEON to enable it.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>

Conflicts:
	arch/arm/vfp/vfpmodule.c
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
vfpmodule: temporary fix for neon mode compile error