All block functions now take an optional mutex parameter that is
atomically unlocked instead of having the user unlock it before hand.
This prevents a ton of race conditions everywhere in the code!
Scheduler keeps crashing all the time when running on multiple cores.
This patch disabled the load balancer, which seems to get rid of most
scheduler crashes.
If thread was blocked, but had not reached block queue, you might
already get an unblock request which would fail on an assertion.
If blocked thread was load balanced to another processor and unblocked
simultaneously, there was a race condition.
This makes scheduler preemption much cleaner as bsb does not have to
send smp messages to notify other processes about timer interrupt.
Also PIT percision is now "full" 0.8 us instead of 1 ms that I was using
before.
Change Semaphore -> ThreadBlocker
This was not a semaphore, I just named it one because I didn't know
what semaphore was. I have meant to change this sooner, but it was in
no way urgent :D
Implement SMP events. Processors can now be sent SMP events through
IPIs. SMP events can be sent either to a single processor or broadcasted
to every processor.
PageTable::{map_page,map_range,unmap_page,unmap_range}() now send SMP
event to invalidate TLB caches for the changed pages.
Scheduler no longer uses a global run queue. Each processor has its own
scheduler that keeps track of the load on the processor. Once every
second schedulers do load balancing. Schedulers have no access to other
processors' schedulers, they just see approximate loads. If scheduler
decides that it has too much load, it will send a thread to another
processor through a SMP event.
Schedulers are currently run using the timer interrupt on BSB. This
should be not the case, and each processor should use its LAPIC timer
for interrupts. There is no reason to broadcast SMP event to all
processors when BSB gets timer interrupt.
Old scheduler only achieved 20% idle load on qemu. That was probably a
very inefficient implementation. This new scheduler seems to average
around 1% idle load. This is much closer to what I would expect. On my
own laptop idle load seems to be only around 0.5% on each processor.
Current context saving was very hacky and dependant on compiler
behaviour that was not consistent. Now we always use iret for
context saving. This makes everything more clean.
Scheduler now has its own data SchedulerQueue which holds active nad
blocking thread lists. This removes need for BAN/Errors.h and making
current thread separate element instead of iterator into linked list.
This makes it possible to have current_thread on each processor
instead of a global one in Scheduler.
This allows us to allocate processor stacks, and other per processor
structures dynamically in runtime. Giving processor stack to
ap_trampoline feels super hacky, but it works for now.
This function was used when processes could die at any point in time.
Now that processes can only die in known spots, we can be sure they
are not holding any locks. This allows much more performant locking.
Signal handling code was way too complex. Now everything is
simplified and there is no need for ThreadBlockers.
Only complication that this patch includes is that blocking syscalls
have to manually be made interruptable by signal. There might be some
clever solution to combat this is make this happen automatically.
Bananymous
Bananymous