git: kernel - Add atomic ops features

[Matthew Dillon]

commit 01740954a98f4843efca6fb69b6260c846ff05a6
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Tue Feb 21 23:51:59 2017 -0800

    kernel - Add atomic ops features
    
    * Add <atomicop>_xacquire() and <atomicop>_xrelease() to a bunch of
      atomic ops.  Using this API will elide the operation using Intel's
      TSX extensions (the elides are backwards compatible to cpus that do
      not support TSX).
    
    * Note however that preliminary testing using this API in the spin_lock*()
      and pv_*() interfaces has only led to a reduction of performance and not
      to any improvement, so at the moment we do not intend to use it.  But I
      did the work to add the API calls and I don't want to lose it.

Summary of changes:
 sys/cpu/x86_64/include/atomic.h | 133 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 130 insertions(+), 3 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/01740954a98f4843efca6fb69b6260c846ff05a6


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