tree 0d6bee46baf7c30f7f0e2045b56bda30937325a5
parent 7a7b6d82839f3f5e13f6568fec74d425e497b966
author Howard Hinnant <hhinnant@apple.com> 1343668401 +0000
committer Howard Hinnant <hhinnant@apple.com> 1343668401 +0000

Despite my pathological distrust of spin locks, the number just don't lie.  I've put a small spin in __sp_mut::lock() on std::mutex::try_lock(), which is testing quite well.  In my experience, putting in a yield for every failed iteration is also a major performance booster.  This change makes one of the performance tests I was using (a highly contended one) run about 20 times faster.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@160967 91177308-0d34-0410-b5e6-96231b3b80d8