K 10
svn:author
V 6
scottl
K 8
svn:date
V 27
2003-02-26T04:46:21.000000Z
K 7
svn:log
V 595
Bring aac out from under Giant:
- the mutex aac_io_lock protects the main codepaths which handle queues and
  hardware registers.  Only one acquire/release is done in the top-half and
  the taskqueue.  This mutex also applies to the userland command path and
  CAM data path.
- Move the taskqueue to the new Giant-free version.
- Register the disk device with DISKFLAG_NOGIANT so the top-half processing
  runs without Giant.
- Move the dynamic command allocator to the worker thread to avoid locking
  issues with bus_dmamem_alloc().

This gives about 20% improvement in most of my benchmarks.

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