* Use atomic_get_and_set for return value
* Atomics are no longer volatile
* Add missing arch_cpu_pause stub
* Move arch_cpu_idle to arch_cpu header to match
other architectures
* This will be used to implement compressed http streams
* Remove the custom BDataOutput class, and use BDataIO instead, for
easier integration with existing code.
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.
The main purpose of this patch is to eliminate the delay between thread
migration and result of that migration being visible in load statistics.
Such delay, in certain circumstances, may cause some cores to become
overloaded because the scheduler migrates too many threads to them before
the effect of migration becomes apparent.
In order to keep the scheduler tickless core load is computed and updated
only during various scheduler events (i.e. thread enqueue, reschedule, etc).
The problem it creates is that if a core becomes idle its load may remain
outdated for an extended period of time thus resulting in suboptimal thread
migration decisions.
The solution to this problem is to add a timer each time an idle thread is
scheudled which, after kLoadMeasureInterval, would fire and force load
update.
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.
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.
The main reason for this patch is to fix gcc 4.8.2 warning about
hierarchyLevels possibly being used not initialized. Such thing
actually can not happen since all x2APIC CPUs are aware of at least
3 topology levels. However, once more topology levels are introduced
we will have to deal with CPUs that do not report information about all
of them.
User timers may cause another thread to become ready in which case we would
like this to happen before scheduler_reschedule() chooses next thread to
be executed.
UserEvent can be fired from scheduler_reschedule() i.e. while holding current
thread scheduler_lock. If the current thread goes sleep and during reschedule
one of its timers sends a signel to it, then scheduler_enqueue_in_run_queue()
attempts to acquire again its scheduler_lock resulting in a deadlock.
There was also a minor issue with both scheduler_reschedule() and
scheduler_enqueue_in_run_queue() acquiring current CPU scheduler mode lock.
* Fix incorrect cpu vendor name mapping
* Add additional CPU architectures
* Add additional CPU vendors
* Rework PowerPC arch_system_info passing
PVR back for cpu model
On multisocket systems as well as under virtual machines logical CPUs
may use separate TSC. We could attempt to synchronize them what probably
would solve problems on multisocket systems. Unfortunately, when running
under hypervisor there is still a chance that TSC will get out of sync
again (e.g. cpufreq enabled on host when there is no invariant TSC). As
long as we use RDTSC as our main time source the scheduler must accept the
fact that time may go backwards (what isn't really a serious problem).
Add boot loader debug menu option "Save syslog from previous session
during boot". If enabled (defaults to true), the previous session's
debug syslog data is copy to a separate buffer and passed to the
kernel, which writes it back to the file /var/log/previous_syslog.
As long as Haiku still boots, this should now be the most convenient way
to retrieve the output from a kernel crash.
This reverts commit 667617ad043a4587d8d366d5192d9ad291cfa37a.
Scheduler profiler uses CPU local data to store function information, hence
arch_thread_context_switch() usually is not a problem. However, when
we switch to a new thread we end up scheduler_new_thread_entry() instead
of scheduler_reschedule() what may corrupt data collected by the profiler.
The symbol is needed for global objects. Usually, GCC also requires
this, but for some reason, the linking error only occurs when using
Clang.
Signed-off-by: Jérôme Duval <jerome.duval@gmail.com>
* Displays standard CPUID, and shows what the
internal CPUID used by OS.h *should* be.
* Should help out in identifying new CPU's
as all end users have to do is run sysinfo
to get the CPU info + value for OS.h
Nested functions are a (again, broken) GNU extension which is not
supported by Clang. It has been replaced by a bunch of gotos and a
variable that works as a return address.
