From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id 3B7556B003C for ; Thu, 6 Jun 2013 04:02:29 -0400 (EDT) Message-ID: <51B0424A.3090208@parallels.com> Date: Thu, 6 Jun 2013 12:03:22 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v10 04/35] dentry: move to per-sb LRU locks References: <1370287804-3481-1-git-send-email-glommer@openvz.org> <1370287804-3481-5-git-send-email-glommer@openvz.org> <20130605160738.fe46654369044b6d94eadd1b@linux-foundation.org> In-Reply-To: <20130605160738.fe46654369044b6d94eadd1b@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Glauber Costa , linux-fsdevel@vger.kernel.org, Mel Gorman , Dave Chinner , linux-mm@kvack.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, Michal Hocko , Johannes Weiner , hughd@google.com, Greg Thelen , Dave Chinner On 06/06/2013 03:07 AM, 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? > > 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. -- 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