K 10
svn:author
V 6
jasone
K 8
svn:date
V 27
2008-03-07T22:39:39.000000Z
K 7
svn:log
V 966
MFC: Merge malloc(3) improvements and fixes.  The highlights are:

* Avoid re-zeroing memory in calloc() when possible.

* Use pthread mutexes where possible instead of libc "spinlocks", and
  actually spin some during contention before blocking.

* Implement dynamic load balancing of thread-->arena mapping.

* Avoid floating point math in order to avoid increased context switch
  overhead for applications that otherwise would not use floating point
  math.

* Restructure how sbrk() and mmap() are used to acquire memory mappings.
  This provides a way to force malloc to only use sbrk(), which can be
  useful in the context of resource limits.

* Reduce the number of mmap() calls typically necessary when allocating
  a chunk.

* Track dirty unused pages so that they can be purged if they exceed a
  threshold.

* Try to realloc() large objects in place.

* Manage page runs with trees instead of chunk maps, which allows
  logarithmic-time run allocation.

END