From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.18.234]) by e23smtp04.au.ibm.com (8.13.1/8.13.1) with ESMTP id m1R9689S020921 for ; Wed, 27 Feb 2008 20:06:08 +1100 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m1R92kgW4333656 for ; Wed, 27 Feb 2008 20:02:46 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m1R92kRY019080 for ; Wed, 27 Feb 2008 20:02:46 +1100 Message-ID: <47C526F8.8010807@linux.vnet.ibm.com> Date: Wed, 27 Feb 2008 14:31:44 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [RFC][PATCH] page reclaim throttle take2 References: <47C4EF2D.90508@linux.vnet.ibm.com> <20080227143301.4252.KOSAKI.MOTOHIRO@jp.fujitsu.com> <47C4F9C0.5010607@linux.vnet.ibm.com> <47C51856.7060408@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: David Rientjes Cc: KOSAKI Motohiro , KAMEZAWA Hiroyuki , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , Lee Schermerhorn , Nick Piggin List-ID: David Rientjes wrote: > On Wed, 27 Feb 2008, Balbir Singh wrote: > >> Let's forget node hotplug for the moment, but what if someone >> >> 1. Changes the machine configuration and adds more nodes, do we expect the >> kernel to be recompiled? Or is it easier to update /etc/sysctl.conf? >> 2. Uses fake NUMA nodes and increases/decreases the number of nodes across >> reboots. Should the kernel be recompiled? >> > > That is why the proposal was made to make this a static configuration > option, such as CONFIG_NUM_RECLAIM_THREADS_PER_NODE, that will handle both > situations. > You mentioned CONFIG_NUM_RECLAIM_THREADS_PER_CPU and not CONFIG_NUM_RECLAIM_THREADS_PER_NODE. The advantage with syscalls is that even if we get the thing wrong, the system administrator has an alternative. Please look through the existing sysctl's and you'll see what I mean. What is wrong with providing the flexibility that comes with sysctl? We cannot possibly think of all situations and come up with the right answer for a heuristic. Why not come up with a default and let everyone use what works for them? -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- 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