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path: root/net/rds/xlist.h
AgeCommit message (Collapse)Author
2010-09-08RDS: Remove unused XLIST_PTR_TAIL and xlist_protect()Andy Grover
Not used. Signed-off-by: Andy Grover <andy.grover@oracle.com>
2010-09-08rds: recycle FMRs through lockless listsChris Mason
FRM allocation and recycling is performance critical and fairly lock intensive. The current code has a per connection lock that all processes bang on and it becomes a major bottleneck on large systems. This changes things to use a number of cmpxchg based lists instead, allowing us to go through the whole FMR lifecycle without locking inside RDS. Zach Brown pointed out that our usage of cmpxchg for xlist removal is racey if someone manages to remove and add back an FMR struct into the list while another CPU can see the FMR's address at the head of the list. The second CPU might assume the list hasn't changed when in fact any number of operations might have happened in between the deletion and reinsertion. This commit maintains a per cpu count of CPUs that are currently in xlist removal, and establishes a grace period to make sure that nobody can see an entry we have just removed from the list. Signed-off-by: Chris Mason <chris.mason@oracle.com>