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.

0 files changed, 0 insertions, 0 deletions