User spinlock speedups
authorBarret Rhoden <brho@cs.berkeley.edu>
Thu, 2 Oct 2014 01:41:08 +0000 (18:41 -0700)
committerBarret Rhoden <brho@cs.berkeley.edu>
Thu, 2 Oct 2014 01:41:08 +0000 (18:41 -0700)
commit670a57200bfb30b6d9257dba21dc1ab7b58d2edd
tree671241f59ac9ee19124509e31415d0ccde1000b4
parent5ab0b57b171023f67843753384fc5e968bd21a8a
User spinlock speedups

Test, then test-and-set avoids everyone writing EBUSY to the cacheline
when it is already locked.  This cuts down on cache line contention.
user/parlib/spinlock.c