John Baldwin 0c0b25ae91 Implement preemption of kernel threads natively in the scheduler rather ... than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)		2004-07-02 20:21:44 +00:00
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pc	Remove atdevbase and replace it's remaining uses with direct references to	2004-06-10 20:31:00 +00:00
_inttypes.h
_limits.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
_stdint.h	<stdint.h> should define WINT_M{AX,IN} independent from whether WCHAR_MIN is	2004-05-18 16:04:57 +00:00
_types.h	Introduce the cpumask_t type. The purpose of the type is to create a	2004-03-20 20:41:40 +00:00
alpha_cpu.h
asm.h
atomic.h
bootinfo.h
bus_memio.h
bus_pio.h
bus.h
bwx.h
chipset.h
clock.h
clockvar.h
cpu.h	Backed out previous commit. Blind substitution of dev_t by `struct cdev *'	2004-06-20 03:52:50 +00:00
cpuconf.h
cpufunc.h
critical.h
db_machdep.h
elf.h
endian.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
exec.h
float.h	Hide FLT_EVAL_METHOD and DECIMAL_DIG in pre-C99 compilation	2004-04-25 02:36:29 +00:00
floatingpoint.h
fpu.h	Don't clear the exception flags after we finish emulating a	2004-05-06 09:35:57 +00:00
frame.h
ieee.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
ieeefp.h
in_cksum.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
inst.h
intr.h
intrcnt.h
ioctl_bt848.h
ioctl_meteor.h
limits.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
md_var.h
mutex.h
pal.h
param.h	Implement preemption of kernel threads natively in the scheduler rather	2004-07-02 20:21:44 +00:00
pcb.h
pcpu.h
pmap.h	- Remove unused definitions.	2004-06-23 08:06:52 +00:00
proc.h
profile.h	Moved most of the "MI" definitions and declarations from <machine/profile.h>	2004-05-19 15:41:26 +00:00
prom.h
pte.h
ptrace.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
reg.h
reloc.h
resource.h
rpb.h
runq.h
setjmp.h
sf_buf.h	MFamd64	2004-04-18 06:24:51 +00:00
sgmap.h
sigframe.h
signal.h
smp.h
stdarg.h
swiz.h
sysarch.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00
ucontext.h
varargs.h
vmparam.h	Remove the advertsing clause, per the Regent's letter dated July 22, 1999.	2004-04-05 21:00:51 +00:00