From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by kanga.kvack.org (Postfix) with ESMTP id 51DA76B0031 for ; Tue, 18 Feb 2014 17:27:14 -0500 (EST) Received: by mail-pa0-f42.google.com with SMTP id kl14so17344457pab.15 for ; Tue, 18 Feb 2014 14:27:14 -0800 (PST) Received: from mail-pa0-x232.google.com (mail-pa0-x232.google.com [2607:f8b0:400e:c03::232]) by mx.google.com with ESMTPS id yn1si6878184pab.284.2014.02.18.14.27.13 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 18 Feb 2014 14:27:13 -0800 (PST) Received: by mail-pa0-f50.google.com with SMTP id kp14so17442539pab.9 for ; Tue, 18 Feb 2014 14:27:13 -0800 (PST) Date: Tue, 18 Feb 2014 14:27:11 -0800 (PST) From: David Rientjes Subject: Re: ppc: RECLAIM_DISTANCE 10? In-Reply-To: <20140218090658.GA28130@dhcp22.suse.cz> Message-ID: References: <20140218090658.GA28130@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Anton Blanchard , Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, LKML On Tue, 18 Feb 2014, Michal Hocko wrote: > Hi, > I have just noticed that ppc has RECLAIM_DISTANCE reduced to 10 set by > 56608209d34b (powerpc/numa: Set a smaller value for RECLAIM_DISTANCE to > enable zone reclaim). The commit message suggests that the zone reclaim > is desirable for all NUMA configurations. > > History has shown that the zone reclaim is more often harmful than > helpful and leads to performance problems. The default RECLAIM_DISTANCE > for generic case has been increased from 20 to 30 around 3.0 > (32e45ff43eaf mm: increase RECLAIM_DISTANCE to 30). > > I strongly suspect that the patch is incorrect and it should be > reverted. Before I will send a revert I would like to understand what > led to the patch in the first place. I do not see why would PPC use only > LOCAL_DISTANCE and REMOTE_DISTANCE distances and in fact machines I have > seen use different values. > I strongly suspect that the patch is correct since powerpc node distances are different than the architectures you're talking about and get doubled for every NUMA domain that the hardware supports. -- 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