cvs commit: src/sys/fs/unionfs union_subr.c src/sys/kern kern_lock.c src/sys/sys _lockmgr.h _stack.h lockmgr.h proc.h sleepqueue.h stack.h vnode.h src/sys/ufs/ffs ffs_softdep.c

[Attilio Rao]

attilio     2008-04-06 20:08:51 UTC

  FreeBSD src repository

  Modified files:
    sys/fs/unionfs       union_subr.c 
    sys/kern             kern_lock.c 
    sys/sys              lockmgr.h proc.h sleepqueue.h stack.h 
                         vnode.h 
    sys/ufs/ffs          ffs_softdep.c 
  Added files:
    sys/sys              _lockmgr.h _stack.h 
  Log:
  Optimize lockmgr in order to get rid of the pool mutex interlock, of the
  state transitioning flags and of msleep(9) callings.
  Use, instead, an algorithm very similar to what sx(9) and rwlock(9)
  alredy do and direct accesses to the sleepqueue(9) primitive.
  
  In order to avoid writer starvation a mechanism very similar to what
  rwlock(9) uses now is implemented, with the correspective per-thread
  shared lockmgrs counter.
  
  This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and
  lockmgr_args_rw().  These two are like the 2 "normal" versions, but they
  both accept a rwlock as interlock.  In order to realize this, the general
  lockmgr manager function "__lockmgr_args()" has been implemented through
  the generic lock layer. It supports all the blocking primitives, but
  currently only these 2 mappers live.
  
  The patch drops the support for WITNESS atm, but it will be probabilly
  added soon. Also, there is a little race in the draining code which is
  also present in the current CVS stock implementation: if some sharers,
  once they wakeup, are in the runqueue they can contend the lock with
  the exclusive drainer.  This is hard to be fixed but the now committed
  code mitigate this issue a lot better than the (past) CVS version.
  In addition assertive KA_HELD and KA_UNHELD have been made mute
  assertions because they are dangerous and they will be nomore supported
  soon.
  
  In order to avoid namespace pollution, stack.h is splitted into two
  parts: one which includes only the "struct stack" definition (_stack.h)
  and one defining the KPI.  In this way, newly added _lockmgr.h can
  just include _stack.h.
  
  Kernel ABI results heavilly changed by this commit (the now committed
  version of "struct lock" is a lot smaller than the previous one) and
  KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction,
  so manpages and __FreeBSD_version will be updated accordingly.
  
  Tested by:      kris, pho, jeff, danger
  Reviewed by:    jeff
  Sponsored by:   Google, Summer of Code program 2007
  
  Revision  Changes    Path
  1.100     +4 -5      src/sys/fs/unionfs/union_subr.c
  1.128     +809 -627  src/sys/kern/kern_lock.c
  1.1       +49 -0     src/sys/sys/_lockmgr.h (new)
  1.1       +39 -0     src/sys/sys/_stack.h (new)
  1.68      +137 -188  src/sys/sys/lockmgr.h
  1.510     +2 -1      src/sys/sys/proc.h
  1.14      +1 -0      src/sys/sys/sleepqueue.h
  1.5       +1 -6      src/sys/sys/stack.h
  1.335     +4 -2      src/sys/sys/vnode.h
  1.223     +2 -2      src/sys/ufs/ffs/ffs_softdep.c