scheduler: Let ThreadData::ShouldRebalance() choose the actual core

Currently, ThreadData::ShouldRebalance() (and mode specific functions
it calls) only decides whether to migrate thread to another core or not.
However, in most cases it actually needs to find the best candidate for
new core so it could as well return that information.

scheduler: Always protect gCore[High]LoadHeap with spinlock

Should fix #10628. If there is a race condition with a writer getting
minimum or maximum from double ended heap may incorrectly result NULL.
Which is not expected in the most of the thread migration logic. Apart
from that, because of the race condition heap state may be observed as
inconsistent thus failing assertions.
ended heap

scheduler: Improve latencies

scheduler: Estimate the load thread is able to produce

Previous implementation based on the actual load of each core and share
each thread has in that load turned up to be very problematic when
balancing load on very heavily loaded systems (i.e. more threads
consuming all available CPU time than there is logical CPUs).

The new approach is to estimate how much load would a thread produce
if it had all CPU time only for itself. Summing such load estimations
of each thread assigned to a given core we get a rank that contains
much more information than just simple actual core load.

scheduler: Improve recognition of CPU bound threads

scheduler: Improve should_rebalance

scheduler: Inherit penalty and core from creator thread

scheduler: Use single ended heap for CPU heap

scheduler: Add scheduler profiler

A bit hackish implementation of a profiler for the scheduler.
SCHEDULER_ENTER_FUNCTION at the begining of each function aren't nice and
usage of __PRETTY_FUNCTION__ isn't any better (both gcc and clang support
it though), but it was quick to implement and doesn't lose information
on inlined functions. It's just a tool, not an integral part of the kernal
anyway.

scheduler: Encapsulate ThreadData fields

scheduler: Encapsulate CPUEntry fields

scheduler: Encapsulate CoreEntry fields

scheduler: Encapsulate PackageEntry fields

Apart from the refactoring this commit takes the opportunity and removes
unnecessary read locks when choosing a package and a core from idle lists.
The data structures are accessed in a thread safe way and it does not really
matter whether the obtained data becomes outdated just when we release the
lock or during our search for the appropriate package/core.

scheduler: Code refactoring

scheduler: Allow mode to specify time slice length

scheduler: Migrate threads less often in power saving mode

scheduler: Protect package data with rw_spinlock

scheduler: Fix power saving mode and other minor improvements

scheduler: Calculate correct load on SMT processors

scheduler: Improve locking

scheduler: Improve power saving mode, part 2

Consequences of committing & pushing too quickly...

scheduler: Improve power saving mode

* Remove possibility to temporarily disable small task packing.
* When small task packing target gets overloaded continue packing
threads on another core, but avoid migrating the already packed
ones.

Scheduler still tends to needlessly migrate threads to another cores
when under heavier load, but it is now much better than before.

scheduler: Try to pack IRQs in power saving mode

scheduler: Move mode specific logic to separate files

scheduler: Let ThreadData::ShouldRebalance() choose the actual core

Currently, ThreadData::ShouldRebalance() (and mode specific functions
it calls) only decides whether to migrate thread to another core or not.
However, in most cases it actually needs to find the best candidate for
new core so it could as well return that information.

scheduler: Always protect gCore[High]LoadHeap with spinlock

Should fix #10628. If there is a race condition with a writer getting
minimum or maximum from double ended heap may incorrectly result NULL.
Which is not expected in the most of the thread migration logic. Apart
from that, because of the race condition heap state may be observed as
inconsistent thus failing assertions.
ended heap

scheduler: Improve latencies

scheduler: Estimate the load thread is able to produce

Previous implementation based on the actual load of each core and share
each thread has in that load turned up to be very problematic when
balancing load on very heavily loaded systems (i.e. more threads
consuming all available CPU time than there is logical CPUs).

The new approach is to estimate how much load would a thread produce
if it had all CPU time only for itself. Summing such load estimations
of each thread assigned to a given core we get a rank that contains
much more information than just simple actual core load.

scheduler: Improve recognition of CPU bound threads

scheduler: Improve should_rebalance

scheduler: Inherit penalty and core from creator thread

scheduler: Use single ended heap for CPU heap

scheduler: Add scheduler profiler

A bit hackish implementation of a profiler for the scheduler.
SCHEDULER_ENTER_FUNCTION at the begining of each function aren't nice and
usage of __PRETTY_FUNCTION__ isn't any better (both gcc and clang support
it though), but it was quick to implement and doesn't lose information
on inlined functions. It's just a tool, not an integral part of the kernal
anyway.

scheduler: Encapsulate ThreadData fields

scheduler: Encapsulate CPUEntry fields

scheduler: Encapsulate CoreEntry fields

scheduler: Encapsulate PackageEntry fields

Apart from the refactoring this commit takes the opportunity and removes
unnecessary read locks when choosing a package and a core from idle lists.
The data structures are accessed in a thread safe way and it does not really
matter whether the obtained data becomes outdated just when we release the
lock or during our search for the appropriate package/core.

scheduler: Code refactoring

scheduler: Allow mode to specify time slice length

scheduler: Migrate threads less often in power saving mode

scheduler: Protect package data with rw_spinlock

scheduler: Fix power saving mode and other minor improvements

scheduler: Calculate correct load on SMT processors

scheduler: Improve locking

scheduler: Improve power saving mode, part 2

Consequences of committing & pushing too quickly...

scheduler: Improve power saving mode

* Remove possibility to temporarily disable small task packing.
* When small task packing target gets overloaded continue packing
threads on another core, but avoid migrating the already packed
ones.

Scheduler still tends to needlessly migrate threads to another cores
when under heavier load, but it is now much better than before.

scheduler: Try to pack IRQs in power saving mode

scheduler: Move mode specific logic to separate files