Commit Graph

17 Commits

Author SHA1 Message Date
John Birrell
58a7cc5d1b [ The author's description... ]
o Runnable threads are now maintained in priority queues.  The
    implementation requires two things:

      1.) The priority queues must be protected during insertion
          and removal of threads.  Since the kernel scheduler
          must modify the priority queues, a spinlock for
          protection cannot be used.   The functions
          _thread_kern_sched_defer() and _thread_kern_sched_undefer()
          were added to {un}defer kernel scheduler activation.

      2.) A thread (active) priority change can be performed only
          when the thread is removed from the priority queue.  The
          implementation uses a threads active priority when
          inserting it into the queue.

    A by-product is that thread switches are much faster.  A
    separate queue is used for waiting and/or blocked threads,
    and it is searched at most 2 times in the kernel scheduler
    when there are active threads.  It should be possible to
    reduce this to once by combining polling of threads waiting
    on I/O with the loop that looks for timed out threads and
    the minimum timeout value.

  o Functions to defer kernel scheduler activation were added.  These
    are _thread_kern_sched_defer() and _thread_kern_sched_undefer()
    and may be called recursively.  These routines do not block the
    scheduling signal, but latch its occurrence.  The signal handler
    will not call the kernel scheduler when the running thread has
    deferred scheduling, but it will be called when running thread
    undefers scheduling.

  o Added support for _POSIX_THREAD_PRIORITY_SCHEDULING.  All the
    POSIX routines required by this should now be implemented.
    One note, SCHED_OTHER, SCHED_FIFO, and SCHED_RR are required
    to be defined by including pthread.h.  These defines are currently
    in sched.h.  I modified pthread.h to include sched.h but don't
    know if this is the proper thing to do.

  o Added support for priority protection and inheritence mutexes.
    This allows definition of _POSIX_THREAD_PRIO_PROTECT and
    _POSIX_THREAD_PRIO_INHERIT.

  o Added additional error checks required by POSIX for mutexes and
    condition variables.

  o Provided a wrapper for sigpending which is marked as a hidden
    syscall.

  o Added a non-portable function as a debugging aid to allow an
    application to monitor thread context switches.  An application
    can install a routine that gets called everytime a thread
    (explicitly created by the application) gets context switched.
    The routine gets passed the pthread IDs of the threads that are
    being switched in and out.

Submitted by: Dan Eischen <eischen@vigrid.com>

Changes by me:

  o Added a PS_SPINBLOCK state to deal with the priority inversion
    problem most often (I think) seen by threads calling malloc/free/realloc.

  o Dispatch signals to the running thread directly rather than at a
    context switch to avoid the situation where the switch never occurs.
1999-03-23 05:07:56 +00:00
John Birrell
dc3a8b52c0 Move the cleanup code that frees memory allocated for a dead thread from
the thread kernel into a garbage collector thread which is started when
the fisrt thread is created (other than the initial thread). This
removes the window of opportunity where a context switch will cause a
thread that has locked the malloc spinlock, to enter the thread kernel,
find there is a dead thread and try to free memory, therefore trying
to lock the malloc spinlock against itself.

The garbage collector thread acts just like any other thread, so
instead of having a spinlock to control accesses to the dead thread
list, it uses a mutex and a condition variable so that it can happily
wait to be signalled when a thread exists.
1998-09-30 06:36:56 +00:00
Dmitrij Tejblum
deb9688ae1 In libc_r, rename vfork syscall to _thread_sys_vfork and make vfork an alias
to fork. It is difficult to do real vfork in libc_r, since almost every
operation with file descriptsor changes _thread_fd_table and friends.

popen(3) works much better with this change.
1998-09-12 22:03:20 +00:00
Alexander Langer
c0e366326f Implement pthread read/write locks as defined by Version 2 of the Single
UNIX Specification.

As with our standard mutexes, process shared locks are not supported at
this time.
1998-09-07 19:01:43 +00:00
John Birrell
fca35cd32f I shouldn't do things early in the morning.
I shouldn't do things early in the morning.
[...]
I shouldn't do things early in the morning.
1998-06-01 02:14:34 +00:00
John Birrell
382306949d Add some missing syscall wrappers. 1998-05-31 23:48:30 +00:00
John Birrell
4a027d50c7 Change signal model to match POSIX (i.e. one set of signal handlers
for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.

Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.

Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.

This is a *big* change!
1998-04-29 09:59:34 +00:00
Alexander Langer
3234f7c1cc Added missing source file uthread_sigwait.c.
Submitted by:	Daniel M. Eischen <deischen@iworks.InterWorks.org>
1997-11-24 23:04:29 +00:00
John Polstra
e91cc88467 Bye bye CPLUSPLUSLIB hack! It's not needed any more.
Don't merge this into -2.2 unless you understand the dependencies on
c++rt0, bsd.lib.mk, and gcc -shared.  I.e., let me do it.
1997-05-06 00:49:36 +00:00
Peter Wemm
7e546392b5 Revert $FreeBSD$ to $Id$ 1997-02-22 15:12:41 +00:00
Julian Elischer
c840cec7c5 Submitted by: John Birrell
uthreads update from the author.
1997-02-05 23:26:09 +00:00
Jordan K. Hubbard
1130b656e5 Make the long-awaited change from $Id$ to $FreeBSD$
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore.  This update would have been
insane otherwise.
1997-01-14 07:20:47 +00:00
Alexander Langer
d0c9b2a226 Added uthread_attr_destroy.c to SRCS.
Submitted by:	John Birrell <jb@cimlogic.com.au>
1996-12-29 02:51:55 +00:00
Jeffrey Hsu
d8fadc0e80 Add uthread_attr_init.c, uthread_attr_setstacksize.c, uthread_mattr_init.c,
uthread_mattr_kind_np.c, uthread_multi_np.c, and uthread_single_np.c.
1996-11-11 09:08:11 +00:00
Julian Elischer
0f7d684755 Submitted by: John Birrell <cimaxp1!jb@werple.net.au>
Here are the diffs for libc_r to get it one step closer to P1003.1c
These make most of the thread/mutex/condvar structures opaque to the
user. There are three functions which have been renamed with _np
suffixes because they are extensions to P1003.1c (I did them for JAVA,
which needs to suspend/resume threads and also start threads suspended).

I've created a new header (pthread_np.h) for the non-POSIX stuff.

The egrep tags stuff in /usr/src/lib/libc_r/Makefile that I uncommented
doesn't work. I think its best to delete it. I don't think libc_r needs
tags anyway, 'cause most of the source is in libc which does have tags.

also:

Here's the first batch of man pages for the thread functions.
The diff to /usr/src/lib/libc_r/Makefile removes some stuff that was
inherited from /usr/src/lib/libc/Makefile that should only be done with
libc.

also:

I should have sent this diff with the pthread(3) man page.
It allows people to type

make -DWANT_LIBC_R world

to get libc_r built with the rest of the world. I put this in the
pthread(3) man page.  The default is still not to build libc_r.


also:
The diff attached adds a pthread(3) man page to /usr/src/share/man/man3.
The idea is that without libc_r installed, this man page will give people
enough info to know that they have to build libc_r.
1996-08-20 08:22:01 +00:00
John Polstra
82d29a82b5 Added a new module "uthread_autoinit.cc". This is a small C++ module.
It uses a static constructor to call _thread_init() at program start-up
time.  That eliminates the need for any initialization hooks in crt0.o.

Added a symbol reference in "uthread_init.c", to ensure that the new
module will always be pulled in when the archive version of the library
is used.

In "Makefile.inc", defined CPLUSPLUSLIB, so that the constructor will be
properly invoked in the shared library.

Suggested by: Christopher Provenzano, Peter Wemm, and others.
1996-02-17 02:19:37 +00:00
Julian Elischer
012dfd00b3 Reviewed by: julian
Submitted by:	 john birrel

One version of the pthreads library
another will follow with differnt actions under some cases..
not QUITE complete
1996-01-22 00:23:58 +00:00