Commit Graph

16 Commits

Author SHA1 Message Date
davidxu
f066519e91 Import my recent 1:1 threading working. some features improved includes:
1. fast simple type mutex.
 2. __thread tls works.
 3. asynchronous cancellation works ( using signal ).
 4. thread synchronization is fully based on umtx, mainly, condition
    variable and other synchronization objects were rewritten by using
    umtx directly. those objects can be shared between processes via
    shared memory, it has to change ABI which does not happen yet.
 5. default stack size is increased to 1M on 32 bits platform, 2M for
    64 bits platform.
As the result, some mysql super-smack benchmarks show performance is
improved massivly.

Okayed by: jeff, mtm, rwatson, scottl
2005-04-02 01:20:00 +00:00
marcel
622fe058c9 Change the thread ID (thr_id_t) used for 1:1 threading from being a
pointer to the corresponding struct thread to the thread ID (lwpid_t)
assigned to that thread. The primary reason for this change is that
libthr now internally uses the same ID as the debugger and the kernel
when referencing to a kernel thread. This allows us to implement the
support for debugging without additional translations and/or mappings.

To preserve the ABI, the 1:1 threading syscalls, including the umtx
locking API have not been changed to work on a lwpid_t. Instead the
1:1 threading syscalls operate on long and the umtx locking API has
not been changed except for the contested bit. Previously this was
the least significant bit. Now it's the most significant bit. Since
the contested bit should not be tested by userland, this change is
not expected to be visible. Just to be sure, UMTX_CONTESTED has been
removed from <sys/umtx.h>.

Reviewed by: mtm@
ABI preservation tested on: i386, ia64
2004-07-02 00:40:07 +00:00
mtm
d835c0621f Make libthr async-signal-safe without costly signal masking. The guidlines I
followed are: Only 3 functions (pthread_cancel, pthread_setcancelstate,
pthread_setcanceltype) are required to be async-signal-safe by POSIX. None of
the rest of the pthread api is required to be async-signal-safe. This means
that only the three mentioned functions are safe to use from inside
signal handlers.
However, there are certain system/libc calls that are
cancellation points that a caller may call from within a signal handler,
and since they are cancellation points calls have to be made into libthr
to test for cancellation and exit the thread if necessary. So, the
cancellation test and thread exit code paths must be async-signal-safe
as well. A summary of the changes follows:

o Almost all of the code paths that masked signals, as well as locking the
  pthread structure now lock only the pthread structure.
o Signals are masked (and left that way) as soon as a thread enters
  pthread_exit().
o The active and dead threads locks now explicitly require that signals
  are masked.
o Access to the isdead field of the pthread structure is protected by both
  the active and dead list locks for writing. Either one is sufficient for
  reading.
o The thread state and type fields have been combined into one three-state
  switch to make it easier to read without requiring a lock. It doesn't need
  a lock for writing (and therefore for reading either) because only the
  current thread can write to it and it is an integer value.
o The thread state field of the pthread structure has been eliminated. It
  was an unnecessary field that mostly duplicated the flags field, but
  required additional locking that would make a lot more code paths require
  signal masking. Any truly unique values (such as PS_DEAD) have been
  reborn as separate members of the pthread structure.
o Since the mutex and condvar pthread functions are not async-signal-safe
  there is no need to muck about with the wait queues when handling
  a signal ...
o ... which also removes the need for wrapping signal handlers and sigaction(2).
o The condvar and mutex async-cancellation code had to be revised as a result
  of some of these changes, which resulted in semi-unrelated changes which
  would have been difficult to work on as a separate commit, so they are
  included as well.

The only part of the changes I am worried about is related to locking for
the pthread joining fields. But, I will take a closer look at them once this
mega-patch is committed.
2004-05-20 12:06:16 +00:00
mtm
e278045fda If a condition variable is statically initialized don't return
an error. Return successfully without doing anything.
2004-03-29 11:24:02 +00:00
mtm
f48b8920dc The thread suspend function now returns ETIMEDOUT, not EAGAIN. 2004-03-29 09:35:07 +00:00
mtm
9481d0539d Stop using signals for synchronizing threads. The performance penalty
was too much.
2004-03-27 14:39:21 +00:00
mtm
5f32d90edd Fix the wrapper function around signals so that a signal handling
thread on one of the mutex or condition variable queues is removed
from those queues before the real signal handler is called.
2003-12-09 11:12:11 +00:00
mtm
cd018fba86 Catchup with _thread_suspend() changes. 2003-06-30 12:35:31 +00:00
mtm
e454f0b243 I botched one of my committs in the last round. Fix it. 2003-05-31 14:38:22 +00:00
mtm
238a1fc561 Use a static lock to ake sure pthread_cond_* functions called
from multiple threads don't initialze the same condition variable
more than once.

Explicitly compare cond pointers with PTHREAD_COND_INITIALIZER instead
of NULL. Just because it happens to be defined as NULL is no reason
to encourage the idea that people can call those functions with
NULL pointers to a condition variable.

Approved by:	re/jhb
2003-05-29 20:54:00 +00:00
mtm
d8dec9f72f Lock the cond queue (condition variables):
Access to the thread's flags and state is protected by
_thread_critical_enter/exit(). When a thread is signaled with a condition
its state must be protected by locking it and disabling
signals before it is taken of the waiters' queue.

Move the implementation of pthread_cond_signal() and pthread_cond_broadcast()
into one function, cond_signal(). Its behaviour is determined by the
last argument, int broadcast. If this is set to 1 it will remove all
waiters, otherwise it will wake up only the first waiter thread.

Remove an extraneous call to pthread_testcancel().

Approved by:	re/blanket libthr
2003-05-24 01:02:16 +00:00
mtm
75e88124d7 Insert a debugging aid:
When in either the mutex or cond queue we notice that the thread
 is already on one of the queues, don't just simply abort(). Print
 out the thread's identifiers and what queue it was on.

Approved by: markm/mentor, re/blanket libthr
2003-05-21 03:41:07 +00:00
mtm
2dcd31b90a Do some cleanup with respect to condition variables. The implementation
of pthread_cond_timedwait() is moved into cond_wait_common().
Pthread_cond_wait() and pthread_cond_timedwait() are now wrappers around
this function. Previously, the former called the latter with the abstime
pointing to 0 time. This violated Posix semantics should an application
have reason to call it with that argument because instead or returning
immediately it would have waited indefinitely for the cv to be signaled.

Approved by:	markm/mentor, re/blanket libthr
Reviewed by:	jeff
2003-05-15 18:17:13 +00:00
jeff
bb610376a5 - Define curthread as _get_curthread() and remove all direct calls to
_get_curthread().  This is similar to the kernel's curthread.  Doing
   this saves stack overhead and is more convenient to the programmer.
 - Pass the pointer to the newly created thread to _thread_init().
 - Remove _get_curthread_slow().
2003-04-02 03:05:39 +00:00
jeff
4b5aacdfc8 - Don't drop and reacquire giant in thread_suspend(). Change callers to do
this manually.  This will facilitate the unrolling of giant.
 - Don't allow giant to recurse anymore.  This should never happen.
2003-04-01 22:41:41 +00:00
jeff
08f648d4cd - Add libthr but don't hook it up to the regular build yet. This is an
adaptation of libc_r for the thr system call interface.  This is beta
   quality code.
2003-04-01 03:46:29 +00:00