Divorce critical sections from spinlocks. Critical sections as denoted by
critical_enter() and critical_exit() are now solely a mechanism for
deferring kernel preemptions. They no longer have any a

Divorce critical sections from spinlocks. Critical sections as denoted by
critical_enter() and critical_exit() are now solely a mechanism for
deferring kernel preemptions. They no longer have any affect on
interrupts. This means that standalone critical sections are now very
cheap as they are simply unlocked integer increments and decrements for the
common case.

Spin mutexes now use a separate KPI implemented in MD code: spinlock_enter()
and spinlock_exit(). This KPI is responsible for providing whatever MD
guarantees are needed to ensure that a thread holding a spin lock won't
be preempted by any other code that will try to lock the same lock. For
now all archs continue to block interrupts in a "spinlock section" as they
did formerly in all critical sections. Note that I've also taken this
opportunity to push a few things into MD code rather than MI. For example,
critical_fork_exit() no longer exists. Instead, MD code ensures that new
threads have the correct state when they are created. Also, we no longer
try to fixup the idlethreads for APs in MI code. Instead, each arch sets
the initial curthread and adjusts the state of the idle thread it borrows
in order to perform the initial context switch.

This change is largely a big NOP, but the cleaner separation it provides
will allow for more efficient alternative locking schemes in other parts
of the kernel (bare critical sections rather than per-CPU spin mutexes
for per-CPU data for example).

Reviewed by: grehan, cognet, arch@, others
Tested on: i386, alpha, sparc64, powerpc, arm, possibly more

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Set the scheduling class of the idle threads to PRI_IDLE.
While there, set their priority with sched_prio() instead of changing it
'by hand'.

Reviewed by: jhb
Approved by: grehan (mentor)

Give the 4bsd scheduler the ability to wake up idle processors
when there is new work to be done.

MFC after: 5 days

Expand the generic, but bogusly formed, copyright notice to include
the license from /usr/src/COPYRIGHT. Since cvs annotate shows that
this was written by jasone, julian, jhb, peter, bmilekic and ob

Expand the generic, but bogusly formed, copyright notice to include
the license from /usr/src/COPYRIGHT. Since cvs annotate shows that
this was written by jasone, julian, jhb, peter, bmilekic and obrien.
cvs log shows that many others may have contributed to this file. As
such, go ahead and use the author of 'FreeBSD Project' for this file.
If this is a problem, please notify me.

# this eliminates the last file in the kernel with an indirect reference
# to /usr/src/COPYRIGHT in the kernel. A few more in userland remain.

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- Change mi_switch() and sched_switch() to accept an optional thread to
switch to. If a non-NULL thread pointer is passed in, then the CPU will
switch to that thread directly rather than calling

- Change mi_switch() and sched_switch() to accept an optional thread to
switch to. If a non-NULL thread pointer is passed in, then the CPU will
switch to that thread directly rather than calling choosethread() to pick
a thread to choose to.
- Make sched_switch() aware of idle threads and know to do
TD_SET_CAN_RUN() instead of sticking them on the run queue rather than
requiring all callers of mi_switch() to know to do this if they can be
called from an idlethread.
- Move constants for arguments to mi_switch() and thread_single() out of
the middle of the function prototypes and up above into their own
section.

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Adjust the priority of the idle threads to be the lowest possible
priority. This is just a comestic nit as the idle thread priorities aren't
used by the schedulers.

Reported by: bde

Always set a process' state to normal when it is fully constructed in
fork1() rather than only doing it for the RFSTOPPED case and then having
to fix it up in other places later on.

- Add a flags parameter to mi_switch. The value of flags may be SW_VOL or
SW_INVOL. Assert that one of these is set in mi_switch() and propery
adjust the rusage statistics. This is to simpli

- Add a flags parameter to mi_switch. The value of flags may be SW_VOL or
SW_INVOL. Assert that one of these is set in mi_switch() and propery
adjust the rusage statistics. This is to simplify the large number of
users of this interface which were previously all required to adjust the
proper counter prior to calling mi_switch(). This also facilitates more
switch and locking optimizations.
- Change all callers of mi_switch() to pass the appropriate paramter and
remove direct references to the process statistics.

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Tidy up loose ends in the idle process. Call the MI cpu_idle() function
for all platforms now.

XXX alpha/sparc64/powerpc should fill in the function.

Submitted by: bde

Halt the cpu on amd64 as well. For some strange reason, this makes
a fair bit of difference to the power consumption and lets my cpu cool
down enough for the temperature sensitive fan controller to

Halt the cpu on amd64 as well. For some strange reason, this makes
a fair bit of difference to the power consumption and lets my cpu cool
down enough for the temperature sensitive fan controller to completely
stop the cpu fan at times.

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Implement cpu_idle() on ia64. We put the processor in a lightweight
halt state that minimizes power consumption while still preserving
cache and TLB coherency. Halting the processor is not conditiona

Implement cpu_idle() on ia64. We put the processor in a lightweight
halt state that minimizes power consumption while still preserving
cache and TLB coherency. Halting the processor is not conditional at
this time. Tested with UP and SMP kernels.

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Use __FBSDID().

Move the flag that indicates an idle thread from the KSE to the thread.
It was always referenced via the thread anyhow.

Reviewed by: jhb (a LOOOOONG time ago)

Add some locking in for a few proc and thread fields.

- Create a new scheduler api that is defined in sys/sched.h
- Begin moving scheduler specific functionality into sched_4bsd.c
- Replace direct manipulation of scheduler data with hooks provided by

- Create a new scheduler api that is defined in sys/sched.h
- Begin moving scheduler specific functionality into sched_4bsd.c
- Replace direct manipulation of scheduler data with hooks provided by the
new api.
- Remove KSE specific state modifications and single runq assumptions from
kern_switch.c

Reviewed by: -arch

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Some kernel threads try to do significant work, and the default KSTACK_PAGES
doesn't give them enough stack to do much before blowing away the pcb.
This adds MI and MD code to allow the allocation of

Some kernel threads try to do significant work, and the default KSTACK_PAGES
doesn't give them enough stack to do much before blowing away the pcb.
This adds MI and MD code to allow the allocation of an alternate kstack
who's size can be speficied when calling kthread_create. Passing the
value 0 prevents the alternate kstack from being created. Note that the
ia64 MD code is missing for now, and PowerPC was only partially written
due to the pmap.c being incomplete there.
Though this patch does not modify anything to make use of the alternate
kstack, acpi and usb are good candidates.

Reviewed by: jake, peter, jhb

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Completely redo thread states.

Reviewed by: davidxu@freebsd.org

Slight cleanup of some comments/whitespace.
Make idle process state more consistant.
Add an assert on thread state.
Clean up idleproc/mi_switch() interaction.
Use a local instead of referencing curth

Slight cleanup of some comments/whitespace.
Make idle process state more consistant.
Add an assert on thread state.
Clean up idleproc/mi_switch() interaction.
Use a local instead of referencing curthread 7 times in a row
(I've been told curthread can be expensive on some architectures)
Remove some commented out code.
Add a little commented out code (completion coming soon)

Reviewed by: jhb@freebsd.org

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Make sure the process state for the idle proc is set correctly
from the beginning.

Thinking about it I came to the conclusion that the KSE states were incorrectly
formulated. The correct states should be:
IDLE: On the idle KSE list for that KSEG
RUNQ: Linked onto the system run

Thinking about it I came to the conclusion that the KSE states were incorrectly
formulated. The correct states should be:
IDLE: On the idle KSE list for that KSEG
RUNQ: Linked onto the system run queue.
THREAD: Attached to a thread and slaved to whatever state the thread is in.

This means that most places where we were adjusting kse state can go away
as it is just moving around because the thread is..
The only places we need to adjust the KSE state is in transition to and from
the idle and run queues.

Reviewed by: jhb@freebsd.org

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Part 1 of KSE-III

The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test pro

Part 1 of KSE-III

The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test program (in tools)

Reviewed by: Almost everyone who counts
(at various times, peter, jhb, matt, alfred, mini, bernd,
and a cast of thousands)

NOTE: this is still Beta code, and contains lots of debugging stuff.
expect slight instability in signals..

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Pre-KSE/M3 commit.
this is a low-functionality change that changes the kernel to access the main
thread of a process via the linked list of threads rather than
assuming that it is embedded in the pro

Pre-KSE/M3 commit.
this is a low-functionality change that changes the kernel to access the main
thread of a process via the linked list of threads rather than
assuming that it is embedded in the process. It IS still embeded there
but remove all teh code that assumes that in preparation for the next commit
which will actually move it out.

Reviewed by: peter@freebsd.org, gallatin@cs.duke.edu, benno rice,

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Modify the critical section API as follows:
- The MD functions critical_enter/exit are renamed to start with a cpu_
prefix.
- MI wrapper functions critical_enter/exit maintain a per-thread nesting

Modify the critical section API as follows:
- The MD functions critical_enter/exit are renamed to start with a cpu_
prefix.
- MI wrapper functions critical_enter/exit maintain a per-thread nesting
count and a per-thread critical section saved state set when entering
a critical section while at nesting level 0 and restored when exiting
to nesting level 0. This moves the saved state out of spin mutexes so
that interlocking spin mutexes works properly.
- Most low-level MD code that used critical_enter/exit now use
cpu_critical_enter/exit. MI code such as device drivers and spin
mutexes use the MI wrappers. Note that since the MI wrappers store
the state in the current thread, they do not have any return values or
arguments.
- mtx_intr_enable() is replaced with a constant CRITICAL_FORK which is
assigned to curthread->td_savecrit during fork_exit().

Tested on: i386, alpha

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Overhaul the per-CPU support a bit:

- The MI portions of struct globaldata have been consolidated into a MI
struct pcpu. The MD per-CPU data are specified via a macro defined in
machine/pcpu.h.

Overhaul the per-CPU support a bit:

- The MI portions of struct globaldata have been consolidated into a MI
struct pcpu. The MD per-CPU data are specified via a macro defined in
machine/pcpu.h. A macro was chosen over a struct mdpcpu so that the
interface would be cleaner (PCPU_GET(my_md_field) vs.
PCPU_GET(md.md_my_md_field)).
- All references to globaldata are changed to pcpu instead. In a UP kernel,
this data was stored as global variables which is where the original name
came from. In an SMP world this data is per-CPU and ideally private to each
CPU outside of the context of debuggers. This also included combining
machine/globaldata.h and machine/globals.h into machine/pcpu.h.
- The pointer to the thread using the FPU on i386 was renamed from
npxthread to fpcurthread to be identical with other architectures.
- Make the show pcpu ddb command MI with a MD callout to display MD
fields.
- The globaldata_register() function was renamed to pcpu_init() and now
init's MI fields of a struct pcpu in addition to registering it with
the internal array and list.
- A pcpu_destroy() function was added to remove a struct pcpu from the
internal array and list.

Tested on: alpha, i386
Reviewed by: peter, jake

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KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is fu

KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after: ha ha ha ha

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