Add a Thread::is_thread(void*) helper that we can use to check that the
incoming donation beneficiary is a valid thread. The O(n) here is a bit sad
and we should eventually rethink the process/thread table data structures.
This introduces a tiny amount of timer drift which I will have to fix
somehow eventually, but it's a huge improvement in timing consistency
as we no longer suddenly jump from e.g 10:45:49.123 to 10:45:50.000.
The scheduler now operates on threads, rather than on processes.
Each process has a main thread, and can have any number of additional
threads. The process exits when the main thread exits.
This patch doesn't actually spawn any additional threads, it merely
does all the plumbing needed to make it possible. :^)
This is accomplished using a new Alarm class and a BlockedSnoozing state.
Basically, you call Process::snooze_until(some_alarm) and then the scheduler
won't wake up the process until some_alarm.is_ringing() returns true.
Only the receive timeout is hooked up yet. You can change the timeout by
calling setsockopt(..., SOL_SOCKET, SO_RCVTIMEO, ...).
Use this mechanism to make /bin/ping report timeouts.
Finally fixed the weird flaky crashing when resizing Terminal windows.
It was because we were dispatching a signal to "current" from the scheduler.
Yet another thing I dislike about even having a "current" process while
we're in the scheduler. Not sure yet how to fix this.
Let the signal handler's kernel stack be a kmalloc() allocation for now.
Once we can do allocation of consecutive physical pages in the supervisor
memory region, we can use that for all types of kernel stacks.
This is really cool! :^)
Apps currently refuse to start if the WindowServer isn't listening on the
socket in /wsportal. This makes sense, but I guess it would also be nice
to have some sort of "wait for server on startup" mode.
This has performance issues, and I'll work on those, but this stuff seems
to actually work and I'm very happy with that.
For now, the WindowServer process will run with high priority,
while the Finalizer process will run with low priority.
Everyone else gets to be "normal".
At the moment, priority simply determines the size of your time slices.
Since we know who's holding the lock, and we're gonna have to yield anyway,
we can just ask the scheduler to donate any remaining ticks to that process.
Instead of processes themselves getting scheduled to finish dying,
let's have a Finalizer process that wakes up whenever someone is dying.
This way we can do all kinds of lock-taking in process cleanup without
risking reentering the scheduler.
- Don't cli() in Process::do_exec() unless current is execing.
Eventually this should go away once the scheduler is less retarded
in the face of interrupts.
- Improved memory access validation for ring0 processes.
We now look at the kernel ELF header to determine if an access
is appropriate. :^) It's very hackish but also kinda neat.
- Have Process::die() put the process into a new "Dying" state where
it can still get scheduled but no signals will be dispatched.
This way we can keep executing in die() but won't get our EIP
hijacked by signal dispatch. The main problem here was that die()
wanted to take various locks.
Also add assertion in Lock that the scheduler isn't currently active.
I've been seeing occasional fuckups that I suspect might be someone called
by the scheduler trying to take a busy lock.
Also use an enum for the rather-confusing return value in dispatch_signal().
I will go through the rest of the signals and set them up with the
appropriate default dispositions at some other point.
It automagically computes %CPU usage based on the number of times a process
has been scheduled between samples. The colonel task is used as idle timer.
This is pretty cool. :^)
GObjects can now register a timer with the GEventLoop. This will eventually
cause GTimerEvents to be dispatched to the GObject.
This needed a few supporting changes in the kernel:
- The PIT now ticks 1000 times/sec.
- select() now supports an arbitrary timeout.
- gettimeofday() now returns something in the tv_usec field.
With these changes, the clock window in guitest2 finally ticks on its own.
The system can finally idle without burning CPU. :^)
There are some issues with scheduling making the mouse cursor sloppy
and unresponsive that need to be dealt with.
Userspace programs can now open /dev/gui_events and read a stream of GUI_Event
structs one at a time.
I was stuck on a stupid problem where we'd reenter Scheduler::yield() due to
having one of the has_data_available_for_reading() implementations using locks.
The kernel now bills processes for time spent in kernelspace and userspace
separately. The accounting is forwarded to the parent process in reap().
This makes the "time" builtin in bash work.
This way the scheduler doesn't need to plumb the exit status into the waiter.
We still plumb the waitee pid though, I don't love it but it can be fixed.
