On 06/06/2013 12:03 PM, Glauber Costa wrote: > On 06/06/2013 03:07 AM, Andrew Morton wrote: >> On Mon, 3 Jun 2013 23:29:33 +0400 Glauber Costa <glommer@xxxxxxxxxx> wrote: >> >>> From: Dave Chinner <dchinner@xxxxxxxxxx> >>> >>> With the dentry LRUs being per-sb structures, there is no real need >>> for a global dentry_lru_lock. The locking can be made more >>> fine-grained by moving to a per-sb LRU lock, isolating the LRU >>> operations of different filesytsems completely from each other. >> >> What's the point to this patch? Is it to enable some additional >> development, or is it a standalone performance tweak? >> >> If the latter then the patch obviously makes this dentry code bloatier >> and straight-line slower. So we're assuming that the multiprocessor >> contention-avoidance benefits will outweigh that cost. Got any proof >> of this? >> >> > This is preparation for the whole point of this series, which is to > abstract the lru manipulation into a list_lru. It is hard to do that > when the dcache has a single lock for all manipulations, and multiple > lists under its umbrella. > > I have updated the Changelog, that now reads: With the dentry LRUs being per-sb structures, there is no real need for a global dentry_lru_lock. The locking can be made more fine-grained by moving to a per-sb LRU lock, isolating the LRU operations of different filesytsems completely from each other. The need for this is independent of any performance consideration that may arise: in the interest of abstracting the lru operations away, it is mandatory that each lru works around its own lock instead of a global lock for all of them. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>