rwsem: Implement writer lock-stealing

This proposal implements writer lock stealing in lib/rwsem.c, just as
Alex Shi's earlier proposal did for the simpler lib/rwsem-spinlock.c

Patches 1 and 2 are small cleanups that I thought I should separate
from the bulk of the changes; Patch 3 is the generic support for write
lock stealing; Patch 4 is the x86 support (optional, only required for
higher performance).

I am not in an ideal position to push this as I will be out of town
starting from the middle of next week. However, I hope that this
proposal will at least get the ball rolling. I did run some basic
testing including David Howell's synchro-test module (as found in
Andrew's -mm tree).

Michel Lespinasse (4):
  rwsem: make the waiter type an enumeration rather than a bitmask
  rwsem: shorter spinlocked section in rwsem_down_failed_common()
  rwsem: implement write lock stealing
  x86 rwsem: avoid taking slow path when stealing write lock

 arch/x86/include/asm/rwsem.h |  28 +++--
 include/linux/rwsem.h        |   2 +
 lib/rwsem.c                  | 252 ++++++++++++++++++++-----------------------
 3 files changed, 139 insertions(+), 143 deletions(-)

-- 
1.8.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/