kernel/scheduler: Add missing initializations to ThreadData::_InitBase().

fQuantumStart and fLastInterruptTime were not set to 0 here, so they
would default to the "malloc-cleared" data and then always overflow
the first time the interrupt time was tracked. I can't find any
reason that was supposed to be the behavior, so just set them to 0.

Also reorder the field initializations to be the same as the class
definition, which should allow some store merging optimizations.

Spotted by KUBSAN.

Cleanup: Remove one trailing whitespace.

scheduler: Inherit estimated load, do not inherit assigned core

The initial core assignment has to be done without any knowledge about
the thread behaviour. Moreover, short lived tasks may spent most of their
time executing on that initial core. This patch attempts to improve the
qualiti of that initial decision.

scheduler: Update priority penalty computation in debug dump

scheduler: Relax penalty cancellation requirements

Priority penalties were made more strict in order to prevent situation
when two or more high priority threads uses up all available CPU time
in such manner that they do not receive a penalty but starve low priority
threads.

However, a significant change to thread priorites has been made since and
now priority of all non real time threads varies in a range from 1 to
static priority minus penalty. This means that the scheduler is able to
prevent thread starvation without any complex penalty policies.

scheduler: Provide more stable core load statistics

Originially, core load was a sum of eastimated loads of all currently
running or ready threads on a given core. Such value is changing very
rapidly preventing the thread migration logic from making any reasonable
decisions.

This patch changes the way core load is computed to make it more stable
thus improving the qualitiy of decisions made by the thread migration logic.
Currently core load is a sum of estimated loads of all threads that have been
ready during last load measurement interval and haven't been migrated or
killed.

scheduler: Fix core unassignment

scheduler: Cache quantum length

scheduler: Fix divide by zero on CPU disable

scheudler: Cache ThreadData::IsCPUBound() result

scheduler: Add ThreadData::{GetPriority, IsIdle, IsRealTime}()

scheduler: Improve latencies

scheduler: Increase thread penalty at fork

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: Introduce strong and weak priority penalties

scheduler: Keep track of the number of the ready threads

scheduler: Improve recognition of CPU bound threads

kernel: Relax cpu_ent::interrupt_time locking

The value isn't accessed by the other CPUs and all writes and reads are
done with interrupts disabled.

scheduler: Improve thread creation performance

scheduler: Work around GCC2 limitations in function inlining

GCC2 won't inline a function if it is used before its definition.

scheduler: Disable load tracking when not needed

scheduler: Thread can not stay on CPU if it has been disabled

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: No need for gQuantumLengths to be global

scheduler: Use precomputed time slice lengths

scheduler: Keep thread effective priority cached

scheduler: Encapsulate CPUEntry fields

scheduler: Encapsulate CoreEntry fields

scheduler: Try to keep thread on the same logical CPU

Some SMT implementations (e.g. recent AMD microarchitectures) have
separate L1d cache for each SMT thread (which AMD decides to call "cores").
This means that we shouldn't move threads to another logical processor too
often even if it belongs to the same core. We aren't very strict about
this as it would complicate load balancing, but we try to reduce unnecessary
migrations.

scheduler: Code refactoring

scheduler: Inherit estimated load, do not inherit assigned core

The initial core assignment has to be done without any knowledge about
the thread behaviour. Moreover, short lived tasks may spent most of their
time executing on that initial core. This patch attempts to improve the
qualiti of that initial decision.

scheduler: Update priority penalty computation in debug dump

scheduler: Relax penalty cancellation requirements

Priority penalties were made more strict in order to prevent situation
when two or more high priority threads uses up all available CPU time
in such manner that they do not receive a penalty but starve low priority
threads.

However, a significant change to thread priorites has been made since and
now priority of all non real time threads varies in a range from 1 to
static priority minus penalty. This means that the scheduler is able to
prevent thread starvation without any complex penalty policies.

scheduler: Provide more stable core load statistics

Originially, core load was a sum of eastimated loads of all currently
running or ready threads on a given core. Such value is changing very
rapidly preventing the thread migration logic from making any reasonable
decisions.

This patch changes the way core load is computed to make it more stable
thus improving the qualitiy of decisions made by the thread migration logic.
Currently core load is a sum of estimated loads of all threads that have been
ready during last load measurement interval and haven't been migrated or
killed.

scheduler: Fix core unassignment

scheduler: Cache quantum length

scheduler: Fix divide by zero on CPU disable

scheudler: Cache ThreadData::IsCPUBound() result

scheduler: Add ThreadData::{GetPriority, IsIdle, IsRealTime}()

scheduler: Improve latencies

scheduler: Increase thread penalty at fork

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: Introduce strong and weak priority penalties

scheduler: Keep track of the number of the ready threads

scheduler: Improve recognition of CPU bound threads

kernel: Relax cpu_ent::interrupt_time locking

The value isn't accessed by the other CPUs and all writes and reads are
done with interrupts disabled.

scheduler: Improve thread creation performance

scheduler: Work around GCC2 limitations in function inlining

GCC2 won't inline a function if it is used before its definition.

scheduler: Disable load tracking when not needed

scheduler: Thread can not stay on CPU if it has been disabled

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: No need for gQuantumLengths to be global

scheduler: Use precomputed time slice lengths

scheduler: Keep thread effective priority cached

scheduler: Encapsulate CPUEntry fields

scheduler: Encapsulate CoreEntry fields

scheduler: Try to keep thread on the same logical CPU

Some SMT implementations (e.g. recent AMD microarchitectures) have
separate L1d cache for each SMT thread (which AMD decides to call "cores").
This means that we shouldn't move threads to another logical processor too
often even if it belongs to the same core. We aren't very strict about
this as it would complicate load balancing, but we try to reduce unnecessary
migrations.

scheduler: Code refactoring