On Tue, Sep 14, 2010 at 08:56:03PM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > When we start taking a reference to the per-ag for every cached > buffer in the system, kernel lockstat profiling on an 8-way create > workload shows the mp->m_perag_lock has higher acquisition rates > than the inode lock and has significantly more contention. That is, > it becomes the highest contended lock in the system. > > The perag lookup is trivial to convert to lock-less RCU lookups > because perag structures never go away. Hence the only thing we need > to protect against is tree structure changes during a grow. THis can > be done simply by replacing the locking in xfs_perag_get() with RCU > read locking. This removes the mp->m_perag_lock completely from this > path. I just noticed that I missed a lookup conversion in reclaim code, so the next version will include that as well. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
