cvs commit: src/sys/conf options src/sys/kern kern_mutex.c

[John Baldwin]

jhb         2004/04/06 12:12:25 PDT

  FreeBSD src repository

  Modified files:
    sys/conf             options 
    sys/kern             kern_mutex.c 
  Log:
  Add a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code
  to awaken all waiters when a contested mutex is released instead of just
  the highest priority waiter.  If the various threads are awakened in
  sequence then each thread may acquire and release the lock in question
  without contention resulting in fewer expensive unlock and lock
  operations.  This old behavior of waking just the highest priority is
  still used if this option is specified.  Making the algorithm conditional
  on a kernel option will allows us to benchmark both cases later and
  determine which one should be used by default.
  
  Requested by:   tanimura-san
  
  Revision  Changes    Path
  1.439     +1 -0      src/sys/conf/options
  1.138     +10 -0     src/sys/kern/kern_mutex.c