From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id D95EF6B0038 for ; Thu, 6 Jun 2013 18:25:48 -0400 (EDT) Date: Thu, 6 Jun 2013 15:25:46 -0700 From: Andrew Morton Subject: Re: [PATCH v10 03/35] dcache: convert dentry_stat.nr_unused to per-cpu counters Message-Id: <20130606152546.52f614d852da32d28a0b460f@linux-foundation.org> In-Reply-To: <51B0834A.8020606@parallels.com> References: <1370287804-3481-1-git-send-email-glommer@openvz.org> <1370287804-3481-4-git-send-email-glommer@openvz.org> <20130605160731.91a5cd3ff700367f5e155d83@linux-foundation.org> <20130606014509.GN29338@dastard> <20130605194801.f9b25abf.akpm@linux-foundation.org> <51B0834A.8020606@parallels.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Dave Chinner , 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 On Thu, 6 Jun 2013 16:40:42 +0400 Glauber Costa wrote: > +/* > + * Here we resort to our own counters instead of using generic per-cpu counters > + * for consistency with what the vfs inode code does. We are expected to harvest > + * better code and performance by having our own specialized counters. > + * > + * Please note that the loop is done over all possible CPUs, not over all online > + * CPUs. The reason for this is that we don't want to play games with CPUs going > + * on and off. If one of them goes off, we will just keep their counters. > + * > + * glommer: See cffbc8a for details, and if you ever intend to change this, > + * please update all vfs counters to match. Handling CPU hotplug is really quite simple - see lib/percpu_counter.c (I can't imagine why percpu_counter_hotcpu_callback() sums all the counters - all it needs to do is to spill hcpu's counter into current's counter). -- 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