On Wed, Sep 29, 2010 at 10:51:40AM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > Under heavy parallel unlink workloads, the incore superblock lock is > heavily trafficed in xfs_mod_incore_sb_batch(). This is despite the > fact that the counters being modified are typically the counters > that are per-cpu and do not require the lock. IOWs, we are locking > and unlocking the superblock lock needlessly, and the result is that > it is third most heavily contended lock in the system under these > workloads. > > Fix this by only locking the superblock lock when we are modifying a > counter protected by it. This completely removes the m_sb_lock from > lock_stat traces during create/remove workloads. God spot of the idiocy there, but I really don't like the patch. I've started writing a small patches series solving the issue slightly better by cleaning up this area a bit. After this we will never use xfs_mod_incore_sb/xfs_mod_incore_sb_batch for the percpu counters but rather make those always go through xfs_icsb_modify_counters. I'll need to quickly finish it up and will send it out soon. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
