From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [PATCH v10 04/35] dentry: move to per-sb LRU locks Date: Thu, 6 Jun 2013 11:56:50 +1000 Message-ID: <20130606015650.GO29338@dastard> References: <1370287804-3481-1-git-send-email-glommer@openvz.org> <1370287804-3481-5-git-send-email-glommer@openvz.org> <20130605160738.fe46654369044b6d94eadd1b@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Glauber Costa , linux-fsdevel@vger.kernel.org, Mel Gorman , linux-mm@kvack.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, Michal Hocko , Johannes Weiner , hughd@google.com, Greg Thelen , Dave Chinner To: Andrew Morton Return-path: Content-Disposition: inline In-Reply-To: <20130605160738.fe46654369044b6d94eadd1b@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Jun 05, 2013 at 04:07:38PM -0700, Andrew Morton wrote: > On Mon, 3 Jun 2013 23:29:33 +0400 Glauber Costa wrote: > > > From: Dave Chinner > > > > 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? It's the separation of the global lock into locks of the same scope the generic LRU list requires. > 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? Well, it will do that too for workloads that span multiple filesytems, but that isn't the point of the patch. it's merely a setting stone... Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org