Commit Graph

137 Commits

Author SHA1 Message Date
Julian Elischer
5498350529 Make debug printf less threatenning and make it only print out once.
MFC after:	2 days
2004-09-07 06:38:22 +00:00
Julian Elischer
6a574b2afc Don't do IPIs on behalf of interrupt threads.
just punt straight on through to teh preemption code.

Make a KASSSERT out of a condition that can no longer occur.
MFC after:	1 week
2004-09-06 07:23:14 +00:00
Julian Elischer
ed062c8d66 Refactor a bunch of scheduler code to give basically the same behaviour
but with slightly cleaned up interfaces.

The KSE structure has become the same as the "per thread scheduler
private data" structure. In order to not make the diffs too great
one is #defined as the other at this time.

The KSE (or td_sched) structure is  now allocated per thread and has no
allocation code of its own.

Concurrency for a KSEGRP is now kept track of via a simple pair of counters
rather than using KSE structures as tokens.

Since the KSE structure is different in each scheduler, kern_switch.c
is now included at the end of each scheduler. Nothing outside the
scheduler knows the contents of the KSE (aka td_sched) structure.

The fields in the ksegrp structure that are to do with the scheduler's
queueing mechanisms are now moved to the kg_sched structure.
(per ksegrp scheduler private data structure). In other words how the
scheduler queues and keeps track of threads is no-one's business except
the scheduler's. This should allow people to write experimental
schedulers with completely different internal structuring.

A scheduler call sched_set_concurrency(kg, N) has been added that
notifies teh scheduler that no more than N threads from that ksegrp
should be allowed to be on concurrently scheduled. This is also
used to enforce 'fainess' at this time so that a ksegrp with
10000 threads can not swamp a the run queue and force out a process
with 1 thread, since the current code will not set the concurrency above
NCPU, and both schedulers will not allow more than that many
onto the system run queue at a time. Each scheduler should eventualy develop
their own methods to do this now that they are effectively separated.

Rejig libthr's kernel interface to follow the same code paths as
linkse for scope system threads. This has slightly hurt libthr's performance
but I will work to recover as much of it as I can.

Thread exit code has been cleaned up greatly.
exit and exec code now transitions a process back to
'standard non-threaded mode' before taking the next step.
Reviewed by:	scottl, peter
MFC after:	1 week
2004-09-05 02:09:54 +00:00
Julian Elischer
44692526be remove unused code
MFC after:	 2 days
2004-09-02 23:37:41 +00:00
Scott Long
9923b511ed Turn PREEMPTION into a kernel option. Make sure that it's defined if
FULL_PREEMPTION is defined.  Add a runtime warning to ULE if PREEMPTION is
enabled (code inspired by the PREEMPTION warning in kern_switch.c).  This
is a possible MT5 candidate.
2004-09-02 18:59:15 +00:00
Julian Elischer
6804a3ab6d Give the 4bsd scheduler the ability to wake up idle processors
when there is new work to be done.

MFC after:	5 days
2004-09-01 06:42:02 +00:00
Julian Elischer
2630e4c90c Give setrunqueue() and sched_add() more of a clue as to
where they are coming from and what is expected from them.

MFC after:	2 days
2004-09-01 02:11:28 +00:00
Peter Wemm
6f96710c60 Backout the previous backout (with scott's ok). sched_ule.c:1.122 is
believed to fix the problem with ULE that this change triggered.
2004-08-28 01:04:44 +00:00
Scott Long
2384290ced Revert the previous change. It works great for 4BSD but causes major
problems for ULE.  The reason is quite unknown and worrisome.
2004-08-20 05:58:38 +00:00
Scott Long
2c86298c6c In maybe_preempt(), ignore threads that are in an inconsistent state. This
is an effective band-aid for at least some of the scheduler corruption seen
recently.  The real fix will involve protecting threads while they are
inconsistent, and will come later.

Submitted by: julian
2004-08-20 05:18:50 +00:00
Scott Long
0f4ad91810 Add a temporary debugging hack to detect a deadlock in setrunqueue(). This
is here so that we can gather stats on the nature of the recent rash of
hard lockups, and in this particular case panic the machine instead of
letting it deadlock forever.
2004-08-10 00:26:25 +00:00
Julian Elischer
1a5cd27b4b Make kg->kg_runnable actually count runnable threads in the ksegrp run queue
instead of only doing it sometimes.. This is not used outdide of debugging code
in the current code, but that will probably change.
2004-08-09 20:36:03 +00:00
Julian Elischer
732d95288a Increase the amount of data exported by KTR in the KTR_RUNQ setting.
This extra data is needed to really follow what is going on in the
threaded case.
2004-08-09 18:21:12 +00:00
John Baldwin
44fe3c1ff0 Don't scare users with a warning about preemption being off when it isn't
yet safe to have on by default.
2004-08-06 15:49:44 +00:00
Robert Watson
1a8cfbc450 Pass a thread argument into cpu_critical_{enter,exit}() rather than
dereference curthread.  It is called only from critical_{enter,exit}(),
which already dereferences curthread.  This doesn't seem to affect SMP
performance in my benchmarks, but improves MySQL transaction throughput
by about 1% on UP on my Xeon.

Head nodding:	jhb, bmilekic
2004-07-27 16:41:01 +00:00
Scott Long
18f480f8f6 Remove the previous hack since it doesn't make a difference and is getting
in the way of debugging.
2004-07-23 19:59:16 +00:00
Scott Long
9493183e77 Disable the PREEMPTION-enabled code in critical_exit() that encourages
switching to a different thread.  This is just a hack to try to improve
stability some more, but likely points closer to the real culprit.
2004-07-22 14:32:48 +00:00
John Baldwin
52eb84641d - Move TDF_OWEPREEMPT, TDF_OWEUPC, and TDF_USTATCLOCK over to td_pflags
since they are only accessed by curthread and thus do not need any
  locking.
- Move pr_addr and pr_ticks out of struct uprof (which is per-process)
  and directly into struct thread as td_profil_addr and td_profil_ticks
  as these variables are really per-thread.  (They are used to defer an
  addupc_intr() that was too "hard" until ast()).
2004-07-16 21:04:55 +00:00
Marcel Moolenaar
2d50560abc Update for the KDB framework:
o  Make debugging code conditional upon KDB instead of DDB.
o  Call kdb_enter() instead of Debugger().
o  Call kdb_backtrace() instead of db_print_backtrace() or backtrace().

kern_mutex.c:
o  Replace checks for db_active with checks for kdb_active and make
   them unconditional.

kern_shutdown.c:
o  s/DDB_UNATTENDED/KDB_UNATTENDED/g
o  s/DDB_TRACE/KDB_TRACE/g
o  Save the TID of the thread doing the kernel dump so the debugger
   knows which thread to select as the current when debugging the
   kernel core file.
o  Clear kdb_active instead of db_active and do so unconditionally.
o  Remove backtrace() implementation.

kern_synch.c:
o  Call kdb_reenter() instead of db_error().
2004-07-10 21:36:01 +00:00
Marcel Moolenaar
8b44a2e2c9 Unbreak build for the the !PREEMPTION case: don't define variables
that aren't used in that case.
2004-07-03 00:57:43 +00:00
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
Jeff Roberson
b209e5e3e4 - style fixes to the critical_exit() KASSERT().
Submitted by:	bde
2004-02-02 08:13:27 +00:00
Robert Watson
fca542bcaa Move KASSERT regarding td_critnest to after the value of td is set to
curthread, to avoid warning and incorrect behavior.

Hoped not to mind:	jeff
2004-02-01 02:31:36 +00:00
Jeff Roberson
6767c6547b - Assert that td_critnest > 0 in critical_exit() to catch cases of
unbalanced uses of the critical_* api.
2004-02-01 01:24:54 +00:00
Robert Watson
09a4a69c1d Although sometimes to the uninitiated, it may seem like goup, KSEGOUP
is actually spelt KSEGROUP.  Go figure.

Reported by:	samy@kerneled.com
2003-12-12 21:25:56 +00:00
Peter Wemm
0d2a298904 Initial landing of SMP support for FreeBSD/amd64.
- This is heavily derived from John Baldwin's apic/pci cleanup on i386.
- I have completely rewritten or drastically cleaned up some other parts.
  (in particular, bootstrap)
- This is still a WIP.  It seems that there are some highly bogus bioses
  on nVidia nForce3-150 boards.  I can't stress how broken these boards
  are.  I have a workaround in mind, but right now the Asus SK8N is broken.
  The Gigabyte K8NPro (nVidia based) is also mind-numbingly hosed.
- Most of my testing has been with SCHED_ULE.  SCHED_4BSD works.
- the apic and acpi components are 'standard'.
- If you have an nVidia nForce3-150 board, you are stuck with 'device
  atpic' in addition, because they somehow managed to forget to connect the
  8254 timer to the apic, even though its in the same silicon!  ARGH!
  This directly violates the ACPI spec.
2003-11-17 08:58:16 +00:00
Jeff Roberson
94816f6d52 - Remove the correct thread from the run queue in setrunqueue(). This
fixes ULE + KSE.
2003-10-17 20:53:04 +00:00
Jeff Roberson
7cf90fb376 - Update the sched api. sched_{add,rem,clock,pctcpu} now all accept a td
argument rather than a kse.
2003-10-16 08:39:15 +00:00
David Xu
0e2a4d3aeb Rename P_THREADED to P_SA. P_SA means a process is using scheduler
activations.
2003-06-15 00:31:24 +00:00
David E. O'Brien
677b542ea2 Use __FBSDID(). 2003-06-11 00:56:59 +00:00
Julian Elischer
faaa20f639 When we are spilling threads out of the run queue during panic, make sure we
keep the thread state variable consistent with its real state.
i.e. Don't say it's on the run queue when it isn't.

Also clarify the associated comment.

Turns a double panic back to a single panic :-/

Approved by:	re@ (jhb)
2003-05-21 18:53:25 +00:00
Peter Wemm
cc66ebe2a9 Commit a partial lazy thread switch mechanism for i386. it isn't as lazy
as it could be and can do with some more cleanup.  Currently its under
options LAZY_SWITCH.  What this does is avoid %cr3 reloads for short
context switches that do not involve another user process.  ie: we can
take an interrupt, switch to a kthread and return to the user without
explicitly flushing the tlb.  However, this isn't as exciting as it could
be, the interrupt overhead is still high and too much blocks on Giant
still.  There are some debug sysctls, for stats and for an on/off switch.

The main problem with doing this has been "what if the process that you're
running on exits while we're borrowing its address space?" - in this case
we use an IPI to give it a kick when we're about to reclaim the pmap.

Its not compiled in unless you add the LAZY_SWITCH option.  I want to fix a
few more things and get some more feedback before turning it on by default.

This is NOT a replacement for Bosko's lazy interrupt stuff.  This was more
meant for the kthread case, while his was for interrupts.  Mine helps a
little for interrupts, but his helps a lot more.

The stats are enabled with options SWTCH_OPTIM_STATS - this has been a
pseudo-option for years, I just added a bunch of stuff to it.

One non-trivial change was to select a new thread before calling
cpu_switch() in the first place.  This allows us to catch the silly
case of doing a cpu_switch() to the current process.  This happens
uncomfortably often.  This simplifies a bit of the asm code in cpu_switch
(no longer have to call choosethread() in the middle).  This has been
implemented on i386 and (thanks to jake) sparc64.  The others will come
soon.  This is actually seperate to the lazy switch stuff.

Glanced at by:  jake, jhb
2003-04-02 23:53:30 +00:00
David Xu
6ce75196ce Adjust code for userland preemptive. Userland can set a quantum in
kse_mailbox to schedule an upcall, this is useful for userland timeout
routine, for example pthread_cond_timedwait().

Also extract upcall scheduling code from kse_reassign and create
a new function called thread_switchout to include these code.

Reviewed by: julain
2003-03-19 05:49:38 +00:00
David Xu
d03c79eea1 Cosmetic change, make it QUEUE_MACRO_DEBUG friendly 2003-03-09 04:27:46 +00:00
Julian Elischer
ac2e415327 Change the process flags P_KSES to be P_THREADED.
This is just a cosmetic change but I've been meaning to do it for about a year.
2003-02-27 02:05:19 +00:00
David Xu
4f6cfa4520 Update comments to reflect new KSE code. 2003-02-19 13:36:51 +00:00
David Xu
02bbffaf3c Move code for detecting PS_NEEDSIGCHK into thread_schedule_upcall,
I think it is a better place to handle it.
2003-02-17 14:41:22 +00:00
Julian Elischer
4a338afd7a Move a bunch of flags from the KSE to the thread.
I was in two minds as to where to put them in the first case..
I should have listenned to the other mind.

Submitted by:	 parts by davidxu@
Reviewed by:	jeff@ mini@
2003-02-17 09:55:10 +00:00
Jeff Roberson
5215b1872f - Split the struct kse into struct upcall and struct kse. struct kse will
soon be visible only to schedulers.  This greatly simplifies much the
   KSE code.

Submitted by:	davidxu
2003-02-17 05:14:26 +00:00
Julian Elischer
6f8132a867 Reversion of commit by Davidxu plus fixes since applied.
I'm not convinced there is anything major wrong with the patch but
them's the rules..

I am using my "David's mentor" hat to revert this as he's
offline for a while.
2003-02-01 12:17:09 +00:00
David Xu
0dbb100b9b Move UPCALL related data structure out of kse, introduce a new
data structure called kse_upcall to manage UPCALL. All KSE binding
and loaning code are gone.

A thread owns an upcall can collect all completed syscall contexts in
its ksegrp, turn itself into UPCALL mode, and takes those contexts back
to userland. Any thread without upcall structure has to export their
contexts and exit at user boundary.

Any thread running in user mode owns an upcall structure, when it enters
kernel, if the kse mailbox's current thread pointer is not NULL, then
when the thread is blocked in kernel, a new UPCALL thread is created and
the upcall structure is transfered to the new UPCALL thread. if the kse
mailbox's current thread pointer is NULL, then when a thread is blocked
in kernel, no UPCALL thread will be created.

Each upcall always has an owner thread. Userland can remove an upcall by
calling kse_exit, when all upcalls in ksegrp are removed, the group is
atomatically shutdown. An upcall owner thread also exits when process is
in exiting state. when an owner thread exits, the upcall it owns is also
removed.

KSE is a pure scheduler entity. it represents a virtual cpu. when a thread
is running, it always has a KSE associated with it. scheduler is free to
assign a KSE to thread according thread priority, if thread priority is changed,
KSE can be moved from one thread to another.

When a ksegrp is created, there is always N KSEs created in the group. the
N is the number of physical cpu in the current system. This makes it is
possible that even an userland UTS is single CPU safe, threads in kernel still
can execute on different cpu in parallel. Userland calls kse_create to add more
upcall structures into ksegrp to increase concurrent in userland itself, kernel
is not restricted by number of upcalls userland provides.

The code hasn't been tested under SMP by author due to lack of hardware.

Reviewed by: julian
2003-01-26 11:41:35 +00:00
Julian Elischer
67f7c1bbe1 Remove a KASSERT that can now happen and add a missing setrunnable. 2003-01-20 03:41:04 +00:00
Julian Elischer
93a7aa79d6 Add code to ddb to allow backtracing an arbitrary thread.
(show thread {address})

Remove the IDLE kse state and replace it with a change in
the way threads sahre KSEs. Every KSE now has a thread, which is
considered its "owner" however a KSE may also be lent to other
threads in the same group to allow completion of in-kernel work.
n this case the owner remains the same and the KSE will revert to the
owner when the other work has been completed.

All creations of upcalls etc. is now done from
kse_reassign() which in turn is called from mi_switch or
thread_exit(). This means that special code can be removed from
msleep() and cv_wait().

kse_release() does not leave a KSE with no thread any more but
converts the existing thread into teh KSE's owner, and sets it up
for doing an upcall. It is just inhibitted from being scheduled until
there is some reason to do an upcall.

Remove all trace of the kse_idle queue since it is no-longer needed.
"Idle" KSEs are now on the loanable queue.
2002-12-28 01:23:07 +00:00
Julian Elischer
24c5baae53 Did you ever notice how stupid bugs show up much clearer
when you see them in a commit message?
2002-10-14 20:43:02 +00:00
Julian Elischer
1f955e2d48 Tidy up the scheduler's code for changing the priority of a thread.
Logically pretty much a NOP.
2002-10-14 20:34:31 +00:00
Jeff Roberson
b43179fbe8 - 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
2002-10-12 05:32:24 +00:00
Julian Elischer
48bfcddd94 Round out the facilty for a 'bound' thread to loan out its KSE
in specific situations. The owner thread must be blocked, and the
borrower can not proceed back to user space with the borrowed KSE.
The borrower will return the KSE on the next context switch where
teh owner wants it back. This removes a lot of possible
race conditions and deadlocks. It is consceivable that the
borrower should inherit the priority of the owner too.
that's another discussion and would be simple to do.

Also, as part of this, the "preallocatd spare thread" is attached to the
thread doing a syscall rather than the KSE. This removes the need to lock
the scheduler when we want to access it, as it's now "at hand".

DDB now shows a lot mor info for threaded proceses though it may need
some optimisation to squeeze it all back into 80 chars again.
(possible JKH project)

Upcalls are now "bound" threads, but "KSE Lending" now means that
other completing syscalls can be completed using that KSE before the upcall
finally makes it back to the UTS. (getting threads OUT OF THE KERNEL is
one of the highest priorities in the KSE system.) The upcall when it happens
will present all the completed syscalls to the KSE for selection.
2002-10-09 02:33:36 +00:00
David Xu
5da2b58aeb set ke_bound to NULL when kse owner thread becomes runnable.
Reviewed by: julian (mentor)
2002-10-03 01:22:05 +00:00
Julian Elischer
9eb1fdea37 Implement basic KSE loaning. This stops a hread that is blocked in BOUND mode
from stopping another thread from completing a syscall, and this allows it to
release its resources etc. Probably more related commits to follow (at least
one I know of)

Initial concept by: julian, dillon
Submitted by:	davidxu
2002-09-29 23:04:34 +00:00
Julian Elischer
33c06e1d3e Indentation does not define a block.. you need breces {} as well..
also add a mutex assert.  (threaded path only)

Submitted by:	davidxu
2002-09-23 05:27:30 +00:00
Julian Elischer
4f0db5e08c Allocate KSEs and KSEGRPs separatly and remove them from the proc structure.
next step is to allow > 1 to be allocated per process. This would give
multi-processor threads. (when the rest of the infrastructure is
in place)

While doing this I noticed libkvm and sys/kern/kern_proc.c:fill_kinfo_proc
are diverging more than they should.. corrective action needed soon.
2002-09-15 23:52:25 +00:00
Julian Elischer
71fad9fdee Completely redo thread states.
Reviewed by:	davidxu@freebsd.org
2002-09-11 08:13:56 +00:00
Julian Elischer
472be95807 Rejig the code to figure out estcpu and work out how long a KSEGRP has been
idle. What was there before was surprisingly ALMOST correct.

Peter and I fried our brains on this for a couple of hours figuring out
what this actually means in the context of multiple threads.

Reviewed by:	peter@freebsd.org
2002-08-30 00:25:49 +00:00
Seigo Tanimura
9eb881f804 - Optimize wakeup() and its friends; if a thread waken up is being
swapped in, we do not have to ask for the scheduler thread to do
  that.

- Assert that a process is not swapped out in runq functions and
  swapout().

- Introduce thread_safetoswapout() for readability.

- In swapout_procs(), perform a test that may block (check of a
  thread working on its vm map) first.  This lets us call swapout()
  with the sched_lock held, providing a better atomicity.
2002-07-30 06:54:05 +00:00
Andrew Gallatin
fe79953325 Allow alphas to do crashdumps: Refuse to run anything in choosethread()
after a panic which is not an interrupt thread, or the thread which
caused the panic.  Also, remove panicstr checks from msleep() and from
cv_wait() in order to allow threads to go to sleep and yeild the cpu
to the panicing thread, or to an interrupt thread which might
be doing the crashdump.

Reviewed by: jhb  (and it was mostly his idea too)
2002-07-17 02:23:44 +00:00
Julian Elischer
c3b98db091 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
2002-07-14 03:43:33 +00:00
Julian Elischer
40e550266d also set the KSE state for the idle KSE/thread case. 2002-07-12 20:16:46 +00:00
John Baldwin
33d7ad1abe Set the thread state of the newly chosen to run thread to TDS_RUNNING in
choosethread() in MI C code instead of doing it in in assembly in all the
various cpu_switch() functions.  This fixes problems on ia64 and sparc64.

Reviewed by:	julian, peter, benno
Tested on:	i386, alpha, sparc64
2002-07-12 18:34:22 +00:00
Julian Elischer
5e3da64ee9 Remove debugging code that I originally only wanted to be there for a couple of days after merge.
Reminded with pointy stick by: jhb
2002-07-11 22:47:58 +00:00
Julian Elischer
e602ba25fd 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..
2002-06-29 17:26:22 +00:00
Peter Wemm
2f9267ec23 Move the "- 1" into the RQB_FFS(mask) macro itself so that
implementations can provide a base zero ffs function if they wish.
This changes
  #define RQB_FFS(mask) (ffs64(mask))
  foo = RQB_FFS(mask) - 1;
to
  #define RQB_FFS(mask) (ffs64(mask) - 1)
  foo = RQB_FFS(mask);
On some platforms we can get the "- 1" for free, eg: those that use the
C code for ffs64().

Reviewed by:	jake (in principle)
2002-06-20 06:21:20 +00:00
Jake Burkholder
d2ac231616 Make the run queue parameters machine dependent. Optimize 64 bit
architectures by using a 64 bit word for the bit array which keeps
track of non-empty queues.

Reviewed by:	peter
2002-05-25 01:12:23 +00:00
Jake Burkholder
0cce52f8eb Remove runq_findproc. This never worked right in the first place and can
be prohibitively expensive.
2002-05-08 04:39:49 +00:00
Matthew Dillon
182da8209d Stage-2 commit of the critical*() code. This re-inlines cpu_critical_enter()
and cpu_critical_exit() and moves associated critical prototypes into their
own header file, <arch>/<arch>/critical.h, which is only included by the
three MI source files that need it.

Backout and re-apply improperly comitted syntactical cleanups made to files
that were still under active development.  Backout improperly comitted program
structure changes that moved localized declarations to the top of two
procedures.  Partially re-apply one of the program structure changes to
move 'mask' into an intermediate block rather then in three separate
sub-blocks to make the code more readable.  Re-integrate bug fixes that Jake
made to the sparc64 code.

Note: In general, developers should not gratuitously move declarations out
of sub-blocks.  They are where they are for reasons of structure, grouping,
readability, compiler-localizability, and to avoid developer-introduced bugs
similar to several found in recent years in the VFS and VM code.

Reviewed by:	jake
2002-04-01 23:51:23 +00:00
Matthew Dillon
d74ac6819b Compromise for critical*()/cpu_critical*() recommit. Cleanup the interrupt
disablement assumptions in kern_fork.c by adding another API call,
cpu_critical_fork_exit().  Cleanup the td_savecrit field by moving it
from MI to MD.  Temporarily move cpu_critical*() from <arch>/include/cpufunc.h
to <arch>/<arch>/critical.c (stage-2 will clean this up).

Implement interrupt deferral for i386 that allows interrupts to remain
enabled inside critical sections.  This also fixes an IPI interlock bug,
and requires uses of icu_lock to be enclosed in a true interrupt disablement.

This is the stage-1 commit.  Stage-2 will occur after stage-1 has stabilized,
and will move cpu_critical*() into its own header file(s) + other things.
This commit may break non-i386 architectures in trivial ways.  This should
be temporary.

Reviewed by:	core
Approved by:	core
2002-03-27 05:39:23 +00:00
Dag-Erling Smørgrav
e97c3e3d5c Rename runq_find() to runq_findproc(), and hide it behind #ifdef DIAGNOSTIC,
as it can have a severe impact on performance under high load, and the bug
it was meant to catch was fixed ages ago.
2002-03-06 15:34:07 +00:00
Matthew Dillon
181df8c9d4 revert last commit temporarily due to whining on the lists. 2002-02-26 20:33:41 +00:00
Matthew Dillon
f96ad4c223 STAGE-1 of 3 commit - allow (but do not require) interrupts to remain
enabled in critical sections and streamline critical_enter() and
critical_exit().

This commit allows an architecture to leave interrupts enabled inside
critical sections if it so wishes.  Architectures that do not wish to do
this are not effected by this change.

This commit implements the feature for the I386 architecture and provides
a sysctl, debug.critical_mode, which defaults to 1 (use the feature).  For
now you can turn the sysctl on and off at any time in order to test the
architectural changes or track down bugs.

This commit is just the first stage.  Some areas of the code, specifically
the MACHINE_CRITICAL_ENTER #ifdef'd code, is strictly temporary and will
be cleaned up in the STAGE-2 commit when the critical_*() functions are
moved entirely into MD files.

The following changes have been made:

	* critical_enter() and critical_exit() for I386 now simply increment
	  and decrement curthread->td_critnest.  They no longer disable
	  hard interrupts.  When critical_exit() decrements the counter to
	  0 it effectively calls a routine to deal with whatever interrupts
	  were deferred during the time the code was operating in a critical
	  section.

	  Other architectures are unaffected.

	* fork_exit() has been conditionalized to remove MD assumptions for
	  the new code.  Old code will still use the old MD assumptions
	  in regards to hard interrupt disablement.  In STAGE-2 this will
	  be turned into a subroutine call into MD code rather then hardcoded
	  in MI code.

	  The new code places the burden of entering the critical section
	  in the trampoline code where it belongs.

	* I386: interrupts are now enabled while we are in a critical section.
	  The interrupt vector code has been adjusted to deal with the fact.
	  If it detects that we are in a critical section it currently defers
	  the interrupt by adding the appropriate bit to an interrupt mask.

	* In order to accomplish the deferral, icu_lock is required.  This
	  is i386-specific.  Thus icu_lock can only be obtained by mainline
	  i386 code while interrupts are hard disabled.  This change has been
	  made.

	* Because interrupts may or may not be hard disabled during a
	  context switch, cpu_switch() can no longer simply assume that
	  PSL_I will be in a consistent state.  Therefore, it now saves and
	  restores eflags.

	* FAST INTERRUPT PROVISION.  Fast interrupts are currently deferred.
	  The intention is to eventually allow them to operate either while
	  we are in a critical section or, if we are able to restrict the
	  use of sched_lock, while we are not holding the sched_lock.

	* ICU and APIC vector assembly for I386 cleaned up.  The ICU code
	  has been cleaned up to match the APIC code in regards to format
	  and macro availability.  Additionally, the code has been adjusted
	  to deal with deferred interrupts.

	* Deferred interrupts use a per-cpu boolean int_pending, and
	  masks ipending, spending, and fpending.  Being per-cpu variables
	  it is not currently necessary to lock; bus cycles modifying them.

	  Note that the same mechanism will enable preemption to be
	  incorporated as a true software interrupt without having to
	  further hack up the critical nesting code.

	* Note: the old critical_enter() code in kern/kern_switch.c is
	  currently #ifdef to be compatible with both the old and new
	  methodology.  In STAGE-2 it will be moved entirely to MD code.

Performance issues:

	One of the purposes of this commit is to enhance critical section
	performance, specifically to greatly reduce bus overhead to allow
	the critical section code to be used to protect per-cpu caches.
	These caches, such as Jeff's slab allocator work, can potentially
	operate very quickly making the effective savings of the new
	critical section code's performance very significant.

	The second purpose of this commit is to allow architectures to
	enable certain interrupts while in a critical section.  Specifically,
	the intention is to eventually allow certain FAST interrupts to
	operate rather then defer.

	The third purpose of this commit is to begin to clean up the
	critical_enter()/critical_exit()/cpu_critical_enter()/
	cpu_critical_exit() API which currently has serious cross pollution
	in MI code (in fork_exit() and ast() for example).

	The fourth purpose of this commit is to provide a framework that
	allows kernel-preempting software interrupts to be implemented
	cleanly.  This is currently used for two forward interrupts in I386.
	Other architectures will have the choice of using this infrastructure
	or building the functionality directly into critical_enter()/
	critical_exit().

	Finally, this commit is designed to greatly improve the flexibility
	of various architectures to manage critical section handling,
	software interrupts, preemption, and other highly integrated
	architecture-specific details.
2002-02-26 17:06:21 +00:00
Julian Elischer
2c1007663f In a threaded world, differnt priorirites become properties of
different entities.  Make it so.

Reviewed by:	jhb@freebsd.org (john baldwin)
2002-02-11 20:37:54 +00:00
John Baldwin
7e1f6dfe9d 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
2001-12-18 00:27:18 +00:00
Jonathan Lemon
6a494eeb34 Change p into ke->ke_proc, this was hidden behind INVARIANTS. 2001-09-18 03:36:21 +00:00
Julian Elischer
b40ce4165d 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
2001-09-12 08:38:13 +00:00
John Baldwin
f583b1d938 Spelling fix in a KASSERT: runq_chose -> runq_choose. 2001-07-04 20:00:48 +00:00
John Baldwin
f34fa851e0 Catch up to header include changes:
- <sys/mutex.h> now requires <sys/systm.h>
- <sys/mutex.h> and <sys/sx.h> now require <sys/lock.h>
2001-03-28 09:17:56 +00:00
Peter Wemm
6fe01250f4 Jake essentially rewrote this. It is not by any stretch of the
imagination a derivative of what I did before.
2001-03-15 05:02:08 +00:00
Dag-Erling Smørgrav
9cbd039343 Assert that the process we're trying to enqueue isn't already there. 2001-03-11 18:57:30 +00:00
John Baldwin
3a3f608288 Add a new informative KASSERT to ensure that a process is in the SRUN state
before we return it to cpu_switch().
2001-03-09 03:59:50 +00:00
Jake Burkholder
f32ded2fb5 - Assert that the proc to return is not NULL in runq_choose the
same as runq_remove.
- bzero the whole struct runq in runq_init just in case its not
  statically allocated.
2001-02-24 14:06:36 +00:00
Jake Burkholder
d5a08a6065 Implement a unified run queue and adjust priority levels accordingly.
- 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.
2001-02-12 00:20:08 +00:00
Jake Burkholder
ef73ae4b0c Use PCPU_GET, PCPU_PTR and PCPU_SET to access all per-cpu variables
other then curproc.
2001-01-10 04:43:51 +00:00
John Baldwin
35e0e5b311 Catch up to moving headers:
- machine/ipl.h -> sys/ipl.h
- machine/mutex.h -> sys/mutex.h
2000-10-20 07:58:15 +00:00
John Baldwin
f6a0af8015 Idle processes are always runnable, so let them state at SRUN. 2000-09-15 19:49:48 +00:00
John Baldwin
4a6404dfc1 Fix some printf format string warnings due to sizeof(int) != sizeof(long) on
the alpha.
2000-09-11 23:55:10 +00:00
Jason Evans
0384fff8c5 Major update to the way synchronization is done in the kernel. Highlights
include:

* Mutual exclusion is used instead of spl*().  See mutex(9).  (Note: The
  alpha port is still in transition and currently uses both.)

* Per-CPU idle processes.

* Interrupts are run in their own separate kernel threads and can be
  preempted (i386 only).

Partially contributed by:	BSDi (BSD/OS)
Submissions by (at least):	cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
Matthew Dillon
36e9f877df Commit major SMP cleanups and move the BGL (big giant lock) in the
syscall path inward.  A system call may select whether it needs the MP
    lock or not (the default being that it does need it).

    A great deal of conditional SMP code for various deadended experiments
    has been removed.  'cil' and 'cml' have been removed entirely, and the
    locking around the cpl has been removed.  The conditional
    separately-locked fast-interrupt code has been removed, meaning that
    interrupts must hold the CPL now (but they pretty much had to anyway).
    Another reason for doing this is that the original separate-lock for
    interrupts just doesn't apply to the interrupt thread mechanism being
    contemplated.

    Modifications to the cpl may now ONLY occur while holding the MP
    lock.  For example, if an otherwise MP safe syscall needs to mess with
    the cpl, it must hold the MP lock for the duration and must (as usual)
    save/restore the cpl in a nested fashion.

    This is precursor work for the real meat coming later: avoiding having
    to hold the MP lock for common syscalls and I/O's and interrupt threads.
    It is expected that the spl mechanisms and new interrupt threading
    mechanisms will be able to run in tandem, allowing a slow piecemeal
    transition to occur.

    This patch should result in a moderate performance improvement due to
    the considerable amount of code that has been removed from the critical
    path, especially the simplification of the spl*() calls.  The real
    performance gains will come later.

Approved by: jkh
Reviewed by: current, bde (exception.s)
Some work taken from: luoqi's patch
2000-03-28 07:16:37 +00:00
Peter Wemm
42cef09ba2 Fix a typo and a bug.
- One RTP_PRIO_REALTIME was meant to be RTP_PRIO_IDLE.
- RTP_PRIO_FIFO was not handled.
- Move the usual case first for setrunqueue() etc.
1999-08-19 16:06:08 +00:00
Peter Wemm
dba6c5a6f9 Extract the next runnable process selection out of cpu_switch() into a
fairly machine independent C routine.  gcc actually does a pretty good
job of this.

Reviewed by:	msmith (in principle)
1999-08-19 00:06:53 +00:00