Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754292AbaBSVpS (ORCPT ); Wed, 19 Feb 2014 16:45:18 -0500 Received: from mail-pb0-f52.google.com ([209.85.160.52]:51245 "EHLO mail-pb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753302AbaBSVpQ (ORCPT ); Wed, 19 Feb 2014 16:45:16 -0500 Date: Wed, 19 Feb 2014 13:45:14 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Michal Hocko cc: Anton Blanchard , Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, LKML Subject: Re: ppc: RECLAIM_DISTANCE 10? In-Reply-To: <20140219091959.GD14783@dhcp22.suse.cz> Message-ID: References: <20140218090658.GA28130@dhcp22.suse.cz> <20140219081644.GA14783@dhcp22.suse.cz> <20140219091959.GD14783@dhcp22.suse.cz> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Feb 2014, Michal Hocko wrote: > Interesting. So is the PPC NUMA basically about local vs. very distant? The point is that it's impossible to tell how distant they are from one NUMA domain to the next NUMA domain. > Should REMOTE_DISTANCE reflect that as well? Or can we have > distance < REMOTE_DISTANCE and it would still make sense to have > zone_reclaim enabled? > Ppc doesn't want to allocate in a different NUMA domain unless required, the latency of a remote access is too high. Everything that isn't in the same domain has a distance >10 and is setup as 2^(domain hops) * 10. We don't have the ability like with a SLIT to define remote nodes to have local latency vs remote or costly latency so the safe setting is a RECLAIM_DISTANCE of 10. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/