- All processes go into the same array of queues, with different
scheduling classes using different portions of the array. This
allows user processes to have their priorities propogated up into
interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
32. We used to have 4 separate arrays of 32 queues each, so this
may not be optimal. The new run queue code was written with this
in mind; changing the number of run queues only requires changing
constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter. This
is intended to be used to create per-cpu run queues. Implement
wrappers for compatibility with the old interface which pass in
the global run queue structure.
- Group the priority level, user priority, native priority (before
propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
This was used to detect when a process' priority had lowered and
it should yield. We now effectively yield on every interrupt.
- Activate propogate_priority(). It should now have the desired
effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
idle loop. It interfered with propogate_priority() because
the idle process needed to do a non-blocking acquire of Giant
and then other processes would try to propogate their priority
onto it. The idle process should not do anything except idle.
vm_page_zero_idle() will return in the form of an idle priority
kernel thread which is woken up at apprioriate times by the vm
system.
- Update struct kinfo_proc to the new priority interface. Deliberately
change its size by adjusting the spare fields. It remained the same
size, but the layout has changed, so userland processes that use it
would parse the data incorrectly. The size constraint should really
be changed to an arbitrary version number. Also add a debug.sizeof
sysctl node for struct kinfo_proc.
Some things needed bits of <i386/include/lock.h> - cy.c now has its
own (only) copy of the COM_(UN)LOCK() macros, and IMASK_(UN)LOCK()
has been moved to <i386/include/apic.h> (AKA <machine/apic.h>).
Reviewed by: jhb
genassym here, but what I've also noticed is that we're dorking
with a mutex directly at assembler level- I'm not sure that this
is wise at this stage in the SMP port- I think it's going to be much
safer for a while to do things in C until SMP wunderkind figure out
what works and slow down this 3 order differential...
it as I was playing with some other ways of doing kernel preemption.
You must still specify the PREEMPTION option in your config file to get a
preemptive kernel.
attributes. This is needed for AST's to be properly posted in a preemptive
kernel. They are backed by two new flags in p_sflag: PS_ASTPENDING and
PS_NEEDRESCHED. They are still accesssed by their old macros:
aston(), astoff(), etc. For completeness, an astpending() macro has been
added to check for a pending AST, and clear_resched() has been added to
clear need_resched().
- Rename syscall2() on the x86 back to syscall() to be consistent with
other architectures.
- Use swi_* function names.
- Use void * to hold cookies to handlers instead of struct intrhand *.
- In sio.c, use 'driver_name' instead of "sio" as the name of the driver
lock to minimize diffs with cy(4).
mtx_enter(lock, type) becomes:
mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)
similarily, for releasing a lock, we now have:
mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.
The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.
Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:
MTX_QUIET and MTX_NOSWITCH
The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:
mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.
Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.
Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.
Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.
Finally, caught up to the interface changes in all sys code.
Contributors: jake, jhb, jasone (in no particular order)
only covers about 3-4 lines.
- Don't lower the IPL while we are on the interrupt stack. Instead, save
the raised IPL and change the saved IPL in sched_lock to IPL_0 before
calling mi_switch(). When we are resumed, restore the saved IPL in
sched_lock to the saved raised IPL so that when we release sched_lock
we won't lower the IPL. Without this, we would get nested interrupts
that would overflow the kernel stack.
Tested by: mjacob
* Optimise the return path for syscalls so that they only restore a minimal
set of registers instead of performing a full exception_return.
A new flag in the trapframe indicates that the frame only holds partial
state. When it is necessary to perform a full state restore (e.g. after an
execve or signal), the flag is cleared to force a full restore.
- If possible, context switch to the thread directly in sched_ithd(),
rather than triggering a delayed ast reschedule.
- Disable interrupts while restoring fpu state in the trap handler,
in order to ensure that we are not preempted in the middle, which
could cause migration to another cpu.
Reviewed by: peter
Tested by: peter (alpha)
* Optimise the return path for syscalls so that they only restore a minimal
set of registers instead of performing a full exception_return.
A new flag in the trapframe indicates that the frame only holds partial
state. When it is necessary to perform a full state restore (e.g. after an
execve or signal), the flag is cleared to force a full restore.
instead of a trapframe directly. (Requested by bde.)
- Convert the alpha switch_trampoline to call fork_exit() and use the MI
fork_return() instead of child_return().
- Axe child_return().
to extract the PC from that to send to addupc_task() so that it can be
called from MI code.
- Remove all traces of have_giant with extreme prejudice and use
mtx_owned(&Giant) instead where appropriate.
- Proc locking.
- P_FOO -> PS_FOO.
- Don't grab Giant just to look in curproc's p_addr during a trap since we
may choose to immediately exit. Instead, delay grabbing Giant a bit
until we actually need it.
- Don't reset 'p' to 'curproc' in syscall() to handle the case of a child
returning from fork1() since children don't return via syscall().
- Remove an XXX comment in ast() that questions the correctness of the
userland check. The code is correct.
- Don't send IPIs for pmap_invalidate_page() or pmap_invalidate_all()
in the UP case.
- Catch up to cpuno -> cpuid.
- Convert some sanity checks that were #ifdef DIAGNOSTIC to KASSERT()'s.
- Rename the per-CPU variable 'cpuno' to 'cpuid'. This was done so that
there is one consistent name across all architectures for a logical
CPU id.
- Remove all traces of IRQ forwarding.
- Add globaldata_register() hook called by globaldata_init() to register
globaldata structures in the cpuid_to_globaldata array.
- Catch up to P_FOO -> PS_FOO.
- Bring across some fixes for forwarded_statclock() from the i386 version
to handle ithreads and idleproc properly.
- Rename addugd_intr_forwarded() to addupc_intr_forwarded() so that it is
the same name on all architectures.
- Set flags in p_sflag instead of calling psignal() from
forward_hardclock().
- Proc locking.
- When we handle an IPI, turn off its bit in the mask of IPI's we are
currently handling so that an IPI doesn't send a CPU into an infinite
loop.
that mutex operations work.
- Enter Giant earlier so we hold it during boot.
- Proc locking.
- Move globaldata_init() into here from mp_machdep.c so that UP kernels
don't depend on mp_machdep.c. Use a callout in the SMP case to register
the boot processor's globaldata in the cpuid_to_globaldata array.
