cvs commit: src/sys/kern lwkt_thread.c

[Matthew Dillon]

dillon      2005/07/20 23:28:50 PDT

DragonFly src repository

  Modified files:
    sys/kern             lwkt_thread.c 
  Log:
  Additional work to try to make panics operate better on SMP systems.
  
  * Fix a bug in a kernel printf() (that occurs in a panic situation) so
    the printf() itself doesn't fault out.
  
  * The idle thread normally must never hold the BGL across a switch, since the
    switch code must switch to the idle thread if no other threads are available.
    However, since the machine can take a fatal kernel trap or panic in the
    context of the idle thread it is possible for the idle thread to hold the
    BGL during these particular situations.  Additionally, the locking code
    assumes that it can just set the thread's mpcount, call lwkt_switch(), and
    not get the cpu back until the scheduler is able to obtain the BGL on
    behalf of the thread.  So have the scheduler deal with this situation.
  
    This makes the scheduler look a bit messier then it really is but the code
    paths in question only run during a panic or fatal kernel trap, so
    performance should not be impaired.
  
  From-dumps-provided-by: Peter Avalos <pavalos at xxxxxxxxxxxx>
  
  Revision  Changes    Path
  1.82      +24 -4     src/sys/kern/lwkt_thread.c


http://www.dragonflybsd.org/cvsweb/src/sys/kern/lwkt_thread.c.diff?r1=1.81&r2=1.82&f=u