cvs commit: src/sys/i386/i386 trap.c

Matthew Dillon dillon at
Mon Nov 21 17:54:17 PST 2005

dillon      2005/11/21 17:52:25 PST

DragonFly src repository

  Modified files:
    sys/i386/i386        trap.c 
  Add a sysctl and tunable kern.trap_mpsafe which allows some traps to run
  without having to hold the MP lock.  The more sophisticated traps, such as
  a VM fault, will still obtain the MP lock.  The sysctl is disabled (0)
  by default.
  The main thing effected by turning this on is T_ASTFLT, which is used to
  switch away from a user process to either a kernel thread (non preemptively)
  or another user process.  When enabled, switching from a user process to
  a kernel thread and back again will not require the MP lock.  However, the
  real benefit will not be realized until more kernel threads run without the
  MP lock.
  Revision  Changes    Path
  1.70      +50 -30    src/sys/i386/i386/trap.c

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