On Fri, Jan 16, 2009 at 06:29:36PM -0800, Mike Waychison wrote: > We've noticed that at times it can become very easy to have a system begin to > livelock on dcache_lock/inode_lock (specifically in atomic_dec_and_lock()) when > a lot of dentries are getting finalized at the same time (massive delete and > large fdtable destructions are two paths I've seen cause problems). > > This patchset is an attempt to try and reduce the locking overheads associated > with final dput() and final iput(). This is done by batching dentries and > inodes into per-process queues and processing them in 'parallel' to consolidate > some of the locking. Hmmmm. This deferring of dput/iput will have the same class of effects on filesystems as the recent reverted changes to make generic_delete_inode() an asynchronous process. That is, it temporally separates the transaction for namespace deletion (i.e. unlink) from the transaction that completes the inode deletion that occurs, typically, during ->clear_inode. See the recent thread titled: [PATCH] async: Don't call async_synchronize_full_special() while holding sb_lock For more details. I suspect that change is likely to cause worse problems than the async changes in that it doesn't have a cap on the number of deferred operations..... > Besides various workload testing, Details? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
