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Date:      Sun, 20 Jun 1999 01:28:56 -0700 (PDT)
From:      John Birrell <jb@FreeBSD.org>
To:        cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   cvs commit: src/lib/libc_r/uthread uthread_poll.c Makefile.inc pthread_private.h uthread_close.c uthread_cond.c uthread_create.c uthread_detach.c uthread_execve.c uthread_exit.c uthread_fd.c uthread_file.c uthread_find_thread.c uthread_fork.c uthread_gc.c ...
Message-ID:  <199906200828.BAA80636@freefall.freebsd.org>

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jb          1999/06/20 01:28:55 PDT

  Modified files:
    lib/libc_r/uthread   Makefile.inc pthread_private.h 
                         uthread_close.c uthread_cond.c 
                         uthread_create.c uthread_detach.c 
                         uthread_execve.c uthread_exit.c 
                         uthread_fd.c uthread_file.c 
                         uthread_find_thread.c uthread_fork.c 
                         uthread_gc.c uthread_info.c 
                         uthread_init.c uthread_join.c 
                         uthread_kern.c uthread_kill.c 
                         uthread_mutex.c uthread_priority_queue.c 
                         uthread_resume_np.c uthread_select.c 
                         uthread_setschedparam.c uthread_sig.c 
                         uthread_sigaction.c uthread_sigwait.c 
                         uthread_suspend_np.c 
  Added files:
    lib/libc_r/uthread   uthread_poll.c 
  Removed files:
    lib/libc_r/uthread   uthread_queue.c 
  Log:
  In the words of the author:
  
    o The polling mechanism for I/O readiness was changed from
      select() to poll().  In additon, a wrapped version of poll()
      is now provided.
  
    o The wrapped select routine now converts each fd_set to a
      poll array so that the thread scheduler doesn't have to
      perform a bitwise search for selected fds each time file
      descriptors are polled for I/O readiness.
  
    o The thread scheduler was modified to use a new queue (_workq)
      for threads that need work.  Threads waiting for I/O readiness
      and spinblocks are added to the work queue in addition to the
      waiting queue.  This reduces the time spent forming/searching
      the array of file descriptors being polled.
  
    o The waiting queue (_waitingq) is now maintained in order of
      thread wakeup time.  This allows the thread scheduler to
      find the nearest wakeup time by looking at the first thread
      in the queue instead of searching the entire queue.
  
    o Removed file descriptor locking for select/poll routines.  An
      application should not rely on the threads library for providing
      this locking; if necessary, the application should use mutexes
      to protect selecting/polling of file descriptors.
  
    o Retrieve and use the kernel clock rate/resolution at startup
      instead of hardcoding the clock resolution to 10 msec (tested
      with kernel running at 1000 HZ).
  
    o All queues have been changed to use queue.h macros.  These
      include the queues of all threads, dead threads, and threads
      waiting for file descriptor locks.
  
    o Added reinitialization of the GC mutex and condition variable
      after a fork.  Also prevented reallocation of the ready queue
      after a fork.
  
    o Prevented the wrapped close routine from closing the thread
      kernel pipes.
  
    o Initialized file descriptor table for stdio entries at thread
      init.
  
    o Provided additional flags to indicate to what queues threads
      belong.
  
    o Moved TAILQ initialization for statically allocated mutex and
      condition variables to after the spinlock.
  
    o Added dispatching of signals to pthread_kill.  Removing the
      dispatching of signals from thread activation broke sigsuspend
      when pthread_kill was used to send a signal to a thread.
  
    o Temporarily set the state of a thread to PS_SUSPENDED when it
      is first created and placed in the list of threads so that it
      will not be accidentally scheduled before becoming a member
      of one of the scheduling queues.
  
    o Change the signal handler to queue signals to the thread kernel
      pipe if the scheduling queues are protected.  When scheduling
      queues are unprotected, signals are then dequeued and handled.
  
    o Ensured that all installed signal handlers block the scheduling
      signal and that the scheduling signal handler blocks all
      other signals.  This ensures that the signal handler is only
      interruptible for and by non-scheduling signals.  An atomic
      lock is used to decide which instance of the signal handler
      will handle pending signals.
  
    o Removed _lock_thread_list and _unlock_thread_list as they are
      no longer used to protect the thread list.
  
    o Added missing RCS IDs to modified files.
  
    o Added checks for appropriate queue membership and activity when
      adding, removing, and searching the scheduling queues.  These
      checks add very little overhead and are enabled when compiled
      with _PTHREADS_INVARIANTS defined.  Suggested and implemented
      by Tor Egge with some modification by me.
  
    o Close a race condition in uthread_close.  (Tor Egge)
  
    o Protect the scheduling queues while modifying them in
      pthread_cond_signal and _thread_fd_unlock.  (Tor Egge)
  
    o Ensure that when a thread gets a mutex, the mutex is on that
      threads list of owned mutexes.  (Tor Egge)
  
    o Set the kernel-in-scheduler flag in _thread_kern_sched_state
      and _thread_kern_sched_state_unlock to prevent a scheduling
      signal from calling the scheduler again.  (Tor Egge)
  
    o Don't use TAILQ_FOREACH macro while searching the waiting
      queue for threads in a sigwait state, because a change of
      state destroys the TAILQ link.  It is actually safe to do
      so, though, because once a sigwaiting thread is found, the
      loop ends and the function returns.  (Tor Egge)
  
    o When dispatching signals to threads, make the thread inherit
      the signal deferral flag of the currently running thread.
      (Tor Egge)
  
  Submitted by: Daniel Eischen <eischen@vigrid.com> and
                Tor Egge <Tor.Egge@fast.no>
  
  Revision  Changes    Path
  1.18      +2 -2      src/lib/libc_r/uthread/Makefile.inc
  1.20      +169 -88   src/lib/libc_r/uthread/pthread_private.h
  1.5       +22 -8     src/lib/libc_r/uthread/uthread_close.c
  1.15      +52 -20    src/lib/libc_r/uthread/uthread_cond.c
  1.13      +16 -22    src/lib/libc_r/uthread/uthread_create.c
  1.8       +11 -8     src/lib/libc_r/uthread/uthread_detach.c
  1.6       +4 -0      src/lib/libc_r/uthread/uthread_execve.c
  1.9       +30 -9     src/lib/libc_r/uthread/uthread_exit.c
  1.11      +55 -15    src/lib/libc_r/uthread/uthread_fd.c
  1.7       +13 -1     src/lib/libc_r/uthread/uthread_file.c
  1.3       +16 -18    src/lib/libc_r/uthread/uthread_find_thread.c
  1.10      +68 -28    src/lib/libc_r/uthread/uthread_fork.c
  1.4       +24 -87    src/lib/libc_r/uthread/uthread_gc.c
  1.11      +26 -5     src/lib/libc_r/uthread/uthread_info.c
  1.11      +43 -10    src/lib/libc_r/uthread/uthread_init.c
  1.7       +2 -1      src/lib/libc_r/uthread/uthread_join.c
  1.19      +653 -834  src/lib/libc_r/uthread/uthread_kern.c
  1.7       +51 -14    src/lib/libc_r/uthread/uthread_kill.c
  1.15      +120 -72   src/lib/libc_r/uthread/uthread_mutex.c
  1.2       +186 -6    src/lib/libc_r/uthread/uthread_priority_queue.c
  1.5       +7 -7      src/lib/libc_r/uthread/uthread_resume_np.c
  1.7       +106 -88   src/lib/libc_r/uthread/uthread_select.c
  1.2       +8 -8      src/lib/libc_r/uthread/uthread_setschedparam.c
  1.17      +119 -91   src/lib/libc_r/uthread/uthread_sig.c
  1.6       +4 -0      src/lib/libc_r/uthread/uthread_sigaction.c
  1.6       +22 -15    src/lib/libc_r/uthread/uthread_sigwait.c
  1.5       +7 -7      src/lib/libc_r/uthread/uthread_suspend_np.c



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