From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Date: Tue, 06 Dec 2005 17:52:56 +0000 Subject: Re: [PATCH 1/2] Zone reclaim V2 Message-Id: <20051206175256.GO11190@wotan.suse.de> List-Id: References: <20051206172444.18786.30131.sendpatchset@schroedinger.engr.sgi.com> In-Reply-To: <20051206172444.18786.30131.sendpatchset@schroedinger.engr.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: akpm@osdl.org, Christoph Hellwig , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, ak@suse.de, torvalds@osdl.org On Tue, Dec 06, 2005 at 09:24:44AM -0800, Christoph Lameter wrote: > Zone reclaim allows the reclaiming of pages from a zone if the number of free > pages falls below the watermark even if other zones still have enough pages > available. Zone reclaim is of particular importance for NUMA machines. It can > be more beneficial to reclaim a page than taking the performance penalties > that come with allocating a page on a remote zone. > > The patch replaces Martin Hick's zone reclaim function (which was never > working properly). > > An arch can control zone_reclaim by setting zone_reclaim_mode during bootup > if it is discovered that the kernel is running on an NUMA configuration. Looks much better. Thanks. But how about auto controlling the variable in generic code based on node_distance() (at least for the non node hotplug case) > +/* > + * Zone reclaim mode > + * > + * If non-zero call zone_reclaim when the number of free pages falls below > + * the watermarks. > + */ > +int zone_reclaim_mode; I would mark it __read_mostly to avoid potential false sharing. -Andi