Commit Graph

164 Commits

Author SHA1 Message Date
Julian Elischer
b2578c6c06 Add some kasserts 2004-09-13 23:02:52 +00:00
Scott Long
1e7fad6b6a Revert the previous round of changes to td_pinned. The scheduler isn't
fully initialed when the pmap layer tries to call sched_pini() early in the
boot and results in an quick panic.  Use ke_pinned instead as was originally
done with Tor's patch.

Approved by: julian
2004-09-11 10:07:22 +00:00
Julian Elischer
5c854accc1 Make up my mind if cpu pinning is stored in the thread structure or the
scheduler specific extension to it. Put it in the extension as
the implimentation details of how the pinning is done needn't be visible
outside the scheduler.

Submitted by:	tegge  (of course!)   (with changes)
MFC after:	3 days
2004-09-10 22:28:33 +00:00
Julian Elischer
3389af30e8 Add some code to allow threads to nominat a sibling to run if theyu are going to sleep.
MFC after:	1 week
2004-09-10 21:04:38 +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
0fe38d47b7 slight code cleanup
MFC after:	1 week
2004-09-05 23:23:58 +00:00
Julian Elischer
bce73aeddb turn on IPIs for 4bsd scheduler by default.
MFC after:	1 week
2004-09-05 02:19:53 +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
00b0483d5c Don't declare a function we are not defining. 2004-09-03 09:19:49 +00:00
Julian Elischer
37c28a022b fix compile for UP 2004-09-03 09:15:10 +00:00
Julian Elischer
293968d8d3 ooops finish last commit.
moved the variables but not the declarations.
2004-09-03 08:19:31 +00:00
Julian Elischer
82a1dfc16d Move 4bsd specific experimental IP code into the 4bsd file.
Move the sysctls into kern.sched
2004-09-03 07:42:31 +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
Julian Elischer
ad59c36ba1 diff reduction for upcoming patch. Use a macro that masks
some of the odd goings on with sub-structures, because they will
go away anyhow.
2004-08-22 05:21:41 +00:00
Julian Elischer
0f54f48225 Properly keep track of how many kses are on the system run queue(s). 2004-08-11 20:54:48 +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
Scott Long
e038d35422 Clean up whitespace, increase consistency and correctness.
Submitted by: bde
2004-07-23 23:09:00 +00:00
Julian Elischer
55d44f79ea When calling scheduler entrypoints for creating new threads and processes,
specify "us" as the thread not the process/ksegrp/kse.
You can always find the others from the thread but the converse is not true.
Theorotically this would lead to runtime being allocated to the wrong
entity in some cases though it is not clear how often this actually happenned.
(would only affect threaded processes and would probably be pretty benign,
but it WAS a bug..)

Reviewed by: peter
2004-07-18 23:36:13 +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
John Baldwin
6942d4339e Set TDF_NEEDRESCHED when a higher priority thread is scheduled in
sched_add() rather than just doing it in sched_wakeup().  The old
ithread preemption code used to set NEEDRESCHED unconditionally if it
didn't preempt which masked this bug in SCHED_4BSD.

Noticed by:	jake
Reported by:	kensmith, marcel
2004-07-13 20:49:13 +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
John Baldwin
bf0acc273a - 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.
2004-07-02 19:09:50 +00:00
Scott Long
36c6fd1c0f Fix another typo in the previous commit. 2004-06-21 23:47:47 +00:00
Scott Long
c38dd4b6bd Fix typo that somehow crept into the previous commit 2004-06-21 22:42:46 +00:00
Scott Long
dc09579417 Add the sysctl node 'kern.sched.name' that has the name of the scheduler
currently in use.  Move the 4bsd kern.quantum node to kern.sched.quantum
for consistency.
2004-06-21 22:05:46 +00:00
Julian Elischer
fa88511615 Nice, is a property of a process as a whole..
I mistakenly moved it to the ksegroup when breaking up the process
structure. Put it back in the proc structure.
2004-06-16 00:26:31 +00:00
Warner Losh
7f8a436ff2 Remove advertising clause from University of California Regent's license,
per letter dated July 22, 1999.

Approved by: core
2004-04-05 21:03:37 +00:00
Doug Rabson
7d5ea13fcd Try not to crash instantly when signalling a libthr program to death. 2004-04-05 15:06:01 +00:00
Robert Watson
8cbec0c8dd The roundrobin callout from sched_4bsd is MPSAFE, so set up the
callout as MPSAFE to avoid grabbing Giant.

Reviewed by:	jhb
2004-03-05 19:27:04 +00:00
John Baldwin
44f3b09204 Switch the sleep/wakeup and condition variable implementations to use the
sleep queue interface:
- Sleep queues attempt to merge some of the benefits of both sleep queues
  and condition variables.  Having sleep qeueus in a hash table avoids
  having to allocate a queue head for each wait channel.  Thus, struct cv
  has shrunk down to just a single char * pointer now.  However, the
  hash table does not hold threads directly, but queue heads.  This means
  that once you have located a queue in the hash bucket, you no longer have
  to walk the rest of the hash chain looking for threads.  Instead, you have
  a list of all the threads sleeping on that wait channel.
- Outside of the sleepq code and the sleep/cv code the kernel no longer
  differentiates between cv's and sleep/wakeup.  For example, calls to
  abortsleep() and cv_abort() are replaced with a call to sleepq_abort().
  Thus, the TDF_CVWAITQ flag is removed.  Also, calls to unsleep() and
  cv_waitq_remove() have been replaced with calls to sleepq_remove().
- The sched_sleep() function no longer accepts a priority argument as
  sleep's no longer inherently bump the priority.  Instead, this is soley
  a propery of msleep() which explicitly calls sched_prio() before
  blocking.
- The TDF_ONSLEEPQ flag has been dropped as it was never used.  The
  associated TDF_SET_ONSLEEPQ and TDF_CLR_ON_SLEEPQ macros have also been
  dropped and replaced with a single explicit clearing of td_wchan.
  TD_SET_ONSLEEPQ() would really have only made sense if it had taken
  the wait channel and message as arguments anyway.  Now that that only
  happens in one place, a macro would be overkill.
2004-02-27 18:52:44 +00:00
Jeff Roberson
f2f51f8ab8 - Disable ithread binding in all cases for now. This doesn't make as much
sense with sched_4bsd as it does with sched_ule.
 - Use P_NOLOAD instead of the absence of td->td_ithd to determine whether or
   not a thread should be accounted for in sched_tdcnt.
2004-02-01 06:20:18 +00:00
Jeff Roberson
ca59f15272 - Keep a variable 'sched_tdcnt' that is used for the local implementation
of sched_load().  This variable tracks the number of running and runnable
   non ithd threads.  This removes the need to traverse the proc table and
   discover how many threads are runnable.
2004-02-01 02:46:47 +00:00
Jeff Roberson
5a2b158d8d - Correct function names listed in KASSERTs. These were copied from other
code and it was sloppy of me not to adjust these sooner.
2004-01-25 08:21:46 +00:00
Jeff Roberson
e17c57b14b - Implement cpu pinning and binding. This is acomplished by keeping a per-
cpu run queue that is only used for pinned or bound threads.

Submitted by:	Chris Bradfield <chrisb@ation.org>
2004-01-25 08:00:04 +00:00
John Baldwin
c55bbb6cb7 Create a separate kthread that executes sched_cpu() once a second. Because
sched_cpu() locks an sx lock (allproc_lock) which can sleep if it fails to
acquire the lock, it is not safe to execute this in a callout handler from
softclock().
2003-12-26 17:07:29 +00:00
Bruce Evans
b698380f33 Quick fix for scaling of statclock ticks in the SMP case. As explained
in the log message for kern_sched.c 1.83 (which should have been
repo-copied to preserve history for this file), the (4BSD) scheduler
algorithm only works right if stathz is nearly 128 Hz.  The old
commit lock said 64 Hz; the scheduler actually wants nearly 16 Hz
but there was a scale factor of 4 to give the requirement of 64 Hz,
and rev.1.83 changed the scale factor so that the requirement became
128 Hz.  The change of the scale factor was incomplete in the SMP
case.  Then scheduling ticks are provided by smp_ncpu CPUs, and the
scheduler cannot tell the difference between this and 1 CPU providing
scheduling ticks smp_ncpu times faster, so we need another scale
factor of smp_ncp or an algorithm change.

This quick fix uses the scale factor without even trying to optimize
the runtime divisions required for this as is done for the other
scale factor.

The main algorithmic problem is the clamp on the scheduling tick counts.
This was 295; it is now approximately 295 * smp_ncpu.  When the limit
is reached, threads get free timeslices and scheduling becomes very
unfair to the threads that don't hit the limit.  The limit can be
reached and maintained in the worst case if the load average is larger
than (limit / effective_stathz - 1) / 2 = 0.65 now (was just 0.08 with
2 CPUs before this change), so there are algorithmic problems even for
a load average of 1.  Fortunately, the worst case isn't common enough
for the problem to be very noticeable (it is mainly for niced CPU hogs
competing with less nice CPU hogs).
2003-11-09 13:45:54 +00:00
David Xu
685a6c448a Return a reasonable number for top or ps to display for M:N thread,
since there is no direct association between M:N thread and kse,
sometimes, a thread does not have a kse, in that case, return a pctcpu
from its last kse, it is not perfect, but gives a good number to be
displayed.
2003-11-08 03:03:17 +00:00
Bruce Evans
89674a9f77 Removed sched_nest variable in sched_switch(). Context switches always
begin with sched_lock held but not recursed, so this variable was
always 0.

Removed fixup of sched_lock.mtx_recurse after context switches in
sched_switch().  Context switches always end with this variable in the
same state that it began in, so there is no need to fix it up.  Only
sched_lock.mtx_lock really needs a fixup.

Replaced fixup of sched_lock.mtx_recurse in fork_exit() by an assertion
that sched_lock is owned and not recursed after it is fixed up.  This
assertion much match the one in mi_switch(), and if sched_lock were
recursed then a non-null fixup of sched_lock.mtx_recurse would probably
be needed again, unlike in sched_switch(), since fork_exit() doesn't
return to its caller in the normal way.
2003-10-29 14:40:41 +00:00
Jeff Roberson
55f2099a70 - The kse may be null in sched_pctcpu().
Reported by:	kris
2003-10-16 21:13:14 +00:00
Jeff Roberson
ae53b483cc - Collapse sched_switchin() and sched_switchout() into sched_switch(). Now
mi_switch() calls sched_switch() which calls cpu_switch().  This is
   actually one less function call than it had been.
2003-10-16 08:53:46 +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
Sam Leffler
c06eb4e293 Change instances of callout_init that specify MPSAFE behaviour to
use CALLOUT_MPSAFE instead of "1" for the second parameter.  This
does not change the behaviour; it just makes the intent more clear.
2003-08-19 17:51:11 +00:00
John Baldwin
70fca4277e - Various style fixes in both code and comments.
- Update some stale comments.
- Sort a couple of includes.
- Only set 'newcpu' in updatepri() if we use it.
- No functional changes.

Obtained from:	bde (via an old diff I got a long time ago)
2003-08-15 21:29:06 +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
Mark Murray
51da11a27a Fix some easy, global, lint warnings. In most cases, this means
making some local variables static. In a couple of cases, this means
removing an unused variable.
2003-04-30 12:57:40 +00:00
John Baldwin
2056d0a168 Add lock assertions for various proc/thread/kse/ksegroup fields to the
scheduler functions.
2003-04-23 18:51:05 +00:00
John Baldwin
0b5318c81a - Assert that the proc lock and sched_lock are held in sched_nice().
- For the 4BSD scheduler, this means that all callers of the static
  function resetpriority() now always hold sched_lock, so don't lock
  sched_lock explicitly in that function.
2003-04-22 20:50:38 +00:00
Jeff Roberson
f7f9e7f34d - Catch up with sched api changes. 2003-04-11 03:39:48 +00:00
Julian Elischer
060563ec50 Move the _oncpu entry from the KSE to the thread.
The entry in the KSE still exists but it's purpose will change a bit
when we add the ability to lock a KSE to a cpu.
2003-04-10 17:35:44 +00:00
Maxime Henrion
4974b53e31 Remove a trailing semicolon in SCHED_QUANTUM definition.
Luckily this didn't cause any bugs.

Spotted by:	Samy Al Bahra <samy@kerneled.com>
2003-03-24 15:16:21 +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
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
8fb913face - Unbreak world. I did not notice that libkvm was still used in some places
to access the pctcpu.  This will have to be sorted out more later as the
   new scheduler requires a procedural interface for this data.  A more
   complete solution will follow.
2003-01-13 03:42:41 +00:00
Jeff Roberson
bcb06d5980 - Move ke_pctcpu and ke_cpticks into the scheduler specific datastructure.
This will prevent access through mechanisms other than the published
   interfaces.
2003-01-12 19:04:49 +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
Jeff Roberson
79acfc497b - Add the new sched_pctcpu() function to the sched_* api.
- Provide a routine in sched_4bsd to add this functionality.
 - Use sched_pctcpu() in kern_proc, which is the one place outside of
   sched_4bsd where the old pctcpu value was accessed directly.

Approved by:	re
2002-11-21 09:30:55 +00:00
Jeff Roberson
06439a04a1 - Move scheduler specific macros and defines out of proc.h
Approved by:	re
2002-11-21 09:14:13 +00:00
Jeff Roberson
148302c9c9 - Move FSCALE back to kern_sync. This is not scheduler specific.
- Create a new callout for lbolt and move it out of schedcpu().  This is not
   scheduler specific either.

Approved by:	re
2002-11-21 08:57:08 +00:00
Jeff Roberson
de028f5a4a - Implement a mechanism for allowing schedulers to place scheduler dependant
data in the scheduler independant structures (proc, ksegrp, kse, thread).
 - Implement unused stubs for this mechanism in sched_4bsd.

Approved by:	re
Reviewed by:	luigi, trb
Tested on:	x86, alpha
2002-11-21 01:22:38 +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